Author Topic: Project car - 1989 75 3.0 V6 [Updated 12 November 2021]  (Read 377270 times)

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Re: Project car - 1989 75 3.0 V6
« Reply #285 on: April 11, 2014, 03:51:41 PM »
Funny, my car is also on stands. But yes, I kept the full length with the flex pipes. So perhaps that is the reason.


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Re: Project car - 1989 75 3.0 V6
« Reply #286 on: April 11, 2014, 08:51:50 PM »
Have you fitted a catalytic converter(s)? I plan to have small diameter cats - 200 cell/in^2 - one per front pipe, instead of feeding into a single cat.

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GT . 3.2 V6 . Q2 . Kyalami Black - Red
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Re: Project car - 1989 75 3.0 V6
« Reply #287 on: April 12, 2014, 06:26:50 AM »
I kept full length, fed into a single cat just where to old centre muffler went [actually just a cat body with a piped centre]. I didn't get under last night, went insulating my new house all arvo until dark.

Shiny - I intended to fit a offset Magnaflow cat one day. Clearance is tight, I can't roll a small Poweraid bottle under my car... But I just haven't got around to doing it.

Magnaflow Metallic Cat, Part number 59905


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Re: Project car - 1989 75 3.0 V6
« Reply #288 on: April 12, 2014, 09:57:30 AM »
4" diameter is probably the smallest around, but I hadn't considered offset ones before.  8)

There's these photos of a CSC setup, which is what I had in mind. Looks like the heat shield is still fitted.

« Last Edit: September 27, 2020, 03:17:01 AM by shiny_car »
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey


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Re: Project car - 1989 75 3.0 V6
« Reply #289 on: April 20, 2014, 07:01:23 PM »
Alright, my csc finishes off and merges to y pipe, then past the crossmember to the cat. Flanges at the csc tips, then at the cat, so the y piece is removable by itself. The y piece and flanges are the culprit in my case, the reason the heat shield doesn't fit.  Might get that rectified if I ever use the offset cats and get the exhaust tucked higher up... Or once my flex pipes wear through...


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Re: Project car - 1989 75 3.0 V6
« Reply #290 on: May 11, 2014, 10:10:34 AM »
Thanks for clarifying, jazig.k.  :)

Monthly update! I've made a start on the interior, and continued working on refitting the gearstick/crossmember.

I attached the new exhaust hangers to the crossmember. Initially, planned to rivet the pieces in position, but had inadequate space to manoeuvre the rivet tool. Instead, enlarged the holes slightly to accommodate M5 bolts; though, still riveted the tips of the hanger pieces together. The attachment also relies as much on JB Weld, so hopefully it holds together adequately. After curing, I touched-up the area with gloss black paint.

Taking some measurements, including distance from top of the original gear knob to the spherical bearing (~326mm). This, of course, is after repositioning the bearing 9mm upwards (ie: prior, would have measured 335mm).

This will be my new gear knob: a 'BLACK Carbon Nero'. BLACK is the brand, Made in Italy, and beautiful quality. 'Carbon Nero' the model, which speaks for itself; the carbon fibre is real, underneath a clear epoxy. The knob is aluminium and quite weighty, comprised of upper and lower pieces bolted together, and with this version, a red plastic central band sandwiched between. Different colour combinations and shapes are available. It's a universal fitment.

The BLACK gear knob trial fitted on the gearstick, confirming it sits in a similar position and distance.

Based upon this, I shortened the gearstick by about 2.5cm/1" to shorten the 'throw', cutting off the tip. I discovered the stick is actually hollow.

The gearstick assembly was pieced together. PTFE-based Super Lube grease was applied to the spherical bearing, and Molygrease to the new lower bearing.

The following schematic was posted on the forums, created by 75 guru, Craig, who happens to live locally to me (though never met you, Craig)!

From that, I was able to use basic trigonometry to calculate the gear knob 'throw' distances:

*original gearstick:
~95mm forward/backward (eg: neutral into 1st/neutral into 2nd gear selection)
~190mm total throw (eg: 1st to 2nd selection)
~55mm side/side gates (ie: moving from 1st-2nd gear gate across to 5th gear gate)

*modified gearstick (repositioned bearing + cut shorter):
~76mm forward/backward
~152mm total throw
~49mm side/side gates

This equates to ~20% reduction in throw, which is worthwhile.

I replaced the original white foam gasket around the top of the housing with fresh self-adhesive closed-cell foam rubber.

The new rubber boot slid onto the gearshift rod. I found it best to slide on from the far end (opposite end to shown), which is 'round' rather than 'squared fork'; some detergent/water made it easier.

Bolted back onto the car. The new issue I faced was fitting the rubber boot onto the base of the housing; now too tight after extending the gearstick lower. However, I think I have a solution and will demonstrate next month.

Now, switching to the interior. Shown with the Recaro interior partly fitted, which will eventually be retrimmed. Rear seat base already removed. Plastic door sill trims unscrewed and unclipped; one long piece per side, covering front + rear sills together.

Front seats being removed. The seats sit atop small circular plastic spacers (allowing the option to lower them ~5mm) and plastic covers over the metal chassis supports. Carpet pretty dirty.

Rear console unscrewed; screw under a carpet trim piece. Wiring passes to the power mirror switch, rear power window rocker buttons, and rear cigarette lighter. The cigarette lighter panel unscrews from the console for easier access to the plug.

Centre console secured with a single bolt to the chassis at the rear.

It sits on the carpet, and at the front is screwed and clipped to the radio console which in turn is screwed to the dash. Sliding the centre console rewards allows separation from the radio console.

Radio console removed. My car was fitted with an aftermarket cheap Pioneer headunit and will be replaced.

The handbrake assembly was unbolted from the chassis to facilitate removal of the centre console. Four bolts, with four spacers underneath. With the handbrake loosened, the centre console was swung up and over, then removed.

After a very thorough vacuum, the carpet presented quite nicely. A couple faded/stained areas will need attention: passenger side beneath the centre console, and rear central area over the transmission hump. Hard to know what caused this fading, but possibly some spilled liquid. And only several small patches of wear, particularly around the driver's feet area.

Under the rear seat is the speedometer signal amplifier. The speedo pulse signal is sent from the gearbox under the car to the amplifier, then onto the speedometer. This is where I can tap into the wires with the Dakota SGI-5 speedo regulator (to recalibrate the speedo after changing tyre size).

On the right side under the rear seat, a random cut wire which I will investigate.

Carpet and sill clips run along the edge, and were unscrewed from the chassis. Then carpet simply peeled away and was removed.

Under the floor sound deadening, a fair amount of random rubbish! Including used and unused rivets, plastic, and cable ties.

On the driver/right side run the hard plastic fuel lines (from tank to engine, and return-line from engine to tank).

Carpet hung on the clothes line, using...the alligator clips on my jumpstart leads. First a snow foam soaking, then washed with the Karcher high pressure hose.

Preparing to remove the parcel shelf trim, first removing the seat back. Speaker grills are clipped to the trim. Then removing the 5.25" dual cone rear speakers, which are fitted to plastic frames bolted from underneath the parcel shelf.

The left/right childseat restraint anchors, and their covers, obstructed removing the trim, so these were unbolted.

With the trim removed, the area was inspected and cleaned. Behind the seat and sound deadener, is the fuel tank in the boot. Access to the top of the rear shock absorbers (dampers) is also from here.

Dust and perished foam on the shelf. The (black) wiring to the centre brake light appears to be a modification that I will need to inspect more closely to see where the power source originates; I suspect directly from the brake pedal switch because I saw a random black wire running along the right door sill.  All the other wires to the parcel shelf area originate from a wiring plug clipped from underneath.

Parcel shelf cleaned.

This is the parcel shelf trim, and centre brake light. Access to the globe behind a cover.

There is a storage bin under a lid, which is labelled for First Aid and Headphones. Indeed, headphone sockets were an option in some markets (unsure if it was in Australia, though), and the wiring actually exists but not the sockets. It would be easy enough to add sockets.

Sure enough, the carpet is very faded, despite being a nice blue-grey colour. The original dark grey was evident under the speaker grill. Inside the storage bin, the carpet is black.

Under the parcel shelf trim, metal support brackets are on each side, which are clamped to the shelf by the speaker frames. The wiring originates from a white plug, supplying audio to the rear speakers, optional headphone sockets, and what appears to be the centre brake light. But as noted earlier, the power to the brake light must have been modified, and cut from the original plug; I can only imagine the original wiring was inadequate to supply current if it was shared with the other brake lights. I will trace the wiring and determine if I can return it to the original plug with an upgrade using a relay.

That was a long update, so thanks for reading. By next month, I should have completed the gearstick fitment, attend to the sagging roof lining, and commence some wiring upgrades.

« Last Edit: September 27, 2020, 03:53:57 AM by shiny_car »
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey


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Re: Project car - 1989 75 3.0 V6
« Reply #291 on: May 11, 2014, 08:52:09 PM »
My '88 3lt has no shelf brake light? No marks from where it was if there ever was one fitted. I see most Alfa's on the AlfaBB have them so presumed it was an overseas thing, until i got my '88 Twinspark. Not that I'm interested in fitting one, I wonder if i have the wires under there...

Your carpet looks fantastic! Mine is shot.
I have read that Alfetta ones fit. I can only remember the foot rest being different, Alfetta having plastic rest bolted in after the carpet goes in and the 75 having it built in under the carpet.
Does anyone have a source for new carpets for either models? I actually wouldn't mind removing the foot rest if i had to use a Alfetta carpet, I have long legs.

I love the look of the shift knob, but it makes me cringe a little... The 3lt leather covered knob is amazing. It fits my hand perfect, the feel is perfect, the shape and size is perfect. I have never found a better knob. There isn't a method of shoving that knob around that is awkward or uncomfortable, IMO. If your knob was a leather one, I want it! It looks like the cheaper one though, which feels half as good... Damned Alfa bean counters...


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Re: Project car - 1989 75 3.0 V6
« Reply #292 on: May 13, 2014, 12:43:00 PM »
My '88 3lt has no shelf brake light? No marks from where it was if there ever was one fitted. I see most Alfa's on the AlfaBB have them so presumed it was an overseas thing, until i got my '88 Twinspark. Not that I'm interested in fitting one, I wonder if i have the wires under there...

It's an interesting point of discussion, that has also taken place on the ausalfa forums where I also post. Seems it is a little inconsistent, and that the centre brake lights were probably fitted when the cars arrived in Australia (ie: not from the factory) to comply with ADR. The style of light can vary, and as with your cars, not always fitted!

Your carpet looks fantastic! Mine is shot.

Yeah, happy with the carpet, and will just 'touch up' the stains with black spray paint. I figure the car has rarely had passengers in it, and that the 135K km is probably genuinely low.

I love the look of the shift knob, but it makes me cringe a little... The 3lt leather covered knob is amazing. It fits my hand perfect, the feel is perfect, the shape and size is perfect. I have never found a better knob.

Ha, well I've not driven the car enough to realise.  :P

I'm pretty sure mine is leather-wrapped. Or at least, it has stitching, which appears faded (originally red or white?) and grubby. I'll have a closer look, and if it's leather, you can have it.

Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey

ARQ164 Shane

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Re: Project car - 1989 75 3.0 V6
« Reply #293 on: May 27, 2014, 07:21:59 AM »
Hello, I made my own pods for 6x9 with thin mdf for the base and an 12mm mdf for the base for the speakers.
I used pop sticks for elevation a can of form then trimmed it all up with a hobby knife and stapled vinyl on it.
Hi Neighbour,
1973 L beetle "Tilly" sold
87 QV 75 ALFA 2.5lt sold
92 auto 164 3lt RIP
91 white 164 Q
89 164 Q part car


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Re: Project car - 1989 75 3.0 V6
« Reply #294 on: May 27, 2014, 07:34:38 PM »
Where do you get your motivation from and can I get some too???  ;)

More nice work, BTW!!!  8) 8) 8)


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Re: Project car - 1989 75 3.0 V6
« Reply #295 on: June 08, 2014, 10:08:09 AM »
@ alphie: nice pods. But I have no intention of running rear speakers; only front + sub. Rears will be removed.

@ Duk: yeah, I'm happy to say I just keep feeling motivated. I think it's largely because I am in a routine of working hard for a full week, then family time, then finally having two days to myself (wife at work, kids in childcare) to do my own thing, so I end up really looking forward to continuing this project a couple days a fortnight.

It was a busy and productive past month. The basic plan with the interior is to strip back to the wiring looms, and by next month I should have the complete dashboard removed. Then I can integrate the alarm, perform various modifications and upgrades, and clean and inspect every part I remove before refitting. Any particularly worn or damaged parts will be replaced if possible, or somehow refurbished.

But firstly, the following is how I modified underneath the gearstick assembly to attach the protective rubber boot. I measured the outer diameter of the alloy housing lip: about 60mm; and the inner diameter of the rubber boot: about 56mm. Normally, the rubber boot would stretch over the lip to secure in position.

My idea was to create an extension or adapter using a cheap off-the-shelf part. Research narrowed down options to either plastic/pvc plumbing pipe, or metal exhaust step-down pieces. After visiting a local plumbing pipe retailer (ie: Bunnings!), I found a plastic irrigation Y-pipe that suited: the inner diameter of the larger end was about 63mm, and the outer diameter of the narrow section about 56mm. With a hacksaw, I cut off one end to create the adapter.

I used some scrap soft pvc plastic cut into a strip, to make a simple bushing, reducing the inner diameter from 63 to about 60mm, providing a snug fit over the gearstick housing. The soft plastic was from a pvc curtain much like this. The adapter was then attached to the housing with a hose clamp.

Refitted to the car, the rubber boot then slid over the adapter, and a second hose clamp attached this in position. Time will tell if it is adequately robust, but I'm confident it is.

Whilst happy with the result, there was of course a flow-on effect. The rubber boot now fouled the exhaust heat shield, so this required modification. The shallow indentation needed to be deeper, beginning with single cut, via a few drilled pilot holes then jigsaw.

After using a mallet, the hydraulic press, and even standing on it (!), I reshaped the shield. Test-fitting confirmed the indentation was now deep enough.

To 're-seal' the gap, I again used scrap parts in my possession, this time some 25mm/1" aluminium angle-bar.

The pieces were reshaped, then drilled and riveted to the heat shield. After some minor fettling, the result was quite satisfactory.

With the carpet, I sprayed the faded patches with gloss black enamel. Because they were small areas, I decided against the expense of specific carpet/vinyl paint.

Back to stripping the interior: removed the roof trim, with its sagging roof lining. I doubt my roof lining is original, and suspect it has been replaced previously, but I don't know what the original lining looks like (in terms of colour and cloth texture).

The rear of the trim is attached by screws behind plastic covers that simply pull off. An attachment point in the centre, and on either side.

Then opened the covers on the grab handles to access bolts. Being careful to retain the stepped washers with each bolt; the washers allow the metal strap handles to slide, so that the handles can be pulled outwards to grab, or neatly pushed flat.

Sagging roof lining very obvious in this photo. Attachment points at the front of the trim are by the sunvisors, and grab handle positions. The sunvisors are secured by two bolts for the hinged corner, and a screw for the retaining clip.

Above the driver's seat there is no grab handle, but the bolts are behind cover pieces.

Once the rear and front bolts and screws are removed, the foam finishing trims detach from the sides.

A single nut/bolt secures the centre light panel to the roof, accessible after unclipping the spotlight.

At the front, the rearview mirror unclips from a bracket, which is bolted to the roof through the switch panel. Behind the spotlight is another nut/bolt.

Very solid springloaded pins hold the rearview mirror to its bracket.

Once the front switch panel is released, the whole trim can be detached. This exposes the wiring.

Along the sides, the roof trim is also supported by protruding ledges. Reasonable force was required to pull the trim over the ledges.

Bare roof once the trim was removed. The wiring disconnects via plugs.

Top side of the roof trim. The light and switch panels are secured by star grab washers, and wiring looms neatly secured with hooks. The grab washers were gently bent and removed with small flat blade screw drivers and pliers, to release the panels from the trim.

The sagging roof trim lining was easy to peel off. Found not to be a failure of the adhesive, but deterioration of the thin foam layer which was perishing. The grubby patch from the previous driver's head was yucky!

After peeling off the lining, the remaining foam required removal to recreate a solid base to apply new adhesive. I discovered my vacuum cleaner could scrape and suck off the foam very neatly without much effort. Resulted in a fresh trim ready for re-lining, a job for the coming month.

Next job, I removed, cleaned, then refitted the B- and C-pillar trims.

The C-pillar trims are secured by a single Christmas-tree clip, and a moulded 'hook' that slides within a metal bracket on the C-pillar. Plus the leading edge is overlapped by the door seal which pulls away easily.

The B-pillar trims are secured by a single screw, and held along the edges by the door seals. The seat belt top anchorage point required unbolting. What initially appeared to be a crack in the trim was actually a moulded gap to slide the belt through.

At the base of the B-pillar passes wiring for the rear door. On the right side runs the 'added' black wire for the centre brake light.

Left side like the right.

At the base of the left C-pillar, I secured wiring with strips of self-adhesive Dynamat sound deadener. On each side I added a cable-tie clip, pushed into pre-existing holes, for the rear demister wires.

After the trims and areas behind were cleaned, the pieces were refitted.

Next, made a start on the dashboard. A while ago, I sold the original steering wheel, with the intention of fitting an aftermarket MOMO version temporarily fitted here.

Steering wheel removed. The car was missing the lower steering column cowl piece. Two bolts secure the (light + wiper) stalk assembly.

Plugs and wiring for the stalks. The (left) light stalk has two upper plugs and a single main (red) power supply wire connected by spade terminal. The (right) wiper stalk has two plugs above and below. Single (purple) wire in the middle for the horn connected by spade terminal. All require disconnection to remove the stalk assembly.

Switch pods, either side of the gauges, unclipped from their base frames. They are held by a series of tabs. The switches are for hazard lights, rear demister, front and rear fog lights; plus a rheostat dial to change dashlight brightness. The frame required unscrewing from the dash to unplug the rheostat.

ARC (Alfa Romeo Control) and clock panel, and ashtray. The ashtray pulls out from its frame, revealing two screws securing the ARC panel. Then they pull away from the dash; the ARC panel has flexible retaining tabs at the top. Three plugs connect to the panel, one for the clock.

Below is the cigarette lighter and trim panel. The panel is clipped in position, and easy to lever off.

With the above parts removed, 5 screws are revealed which secure the upper dashboard section in position. Interestingly, the workshop manual refers to 3 screws behind the cigarette lighter trim, compared with 2 on my car; presumably some versions (perhaps LHD) have the additional screw.

On the right side of the steering column, the small storage bin unclips from position, best levered out from the bottom. Behind the bin are 2 screws; through the gap above, behind the switch pod, are 2 additional screws. Well, should have been 2, but only 1 fitted in my car! The 4 screws help secure the upper dashboard section.

After all screws are removed, this section can be removed. Dashboard rotated forwards to access the plugs first.

Lastly, I removed the windscreen demister grill, which is metal. The grill is press-fitted in position, and can be levered off from one end.

That's it for this month. I should have the dash completely removed by next month and commence wiring upgrades. See you then.

« Last Edit: September 27, 2020, 04:38:15 AM by shiny_car »
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey

Divano Veloce

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Re: Project car - 1989 75 3.0 V6
« Reply #296 on: July 04, 2014, 09:29:45 AM »
Awesome writeup for anyone who wants to repair a sagged headlining in their 75!
1968 Berlina TS
1989 75 TS
1990 75 TS
2007 147 JTD


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Instrument cluster tachometer fading
« Reply #297 on: July 07, 2014, 10:57:39 PM »
Will you be recolouring this faded section of the tachometer Richard?

Interestingly Richard in regards to the clock/warning lights, the first series 75s had a lot more information available here, they had distance to empty, average fuel used etc etc all at the push of a button the same as the 90, they removed these features in the series 2 and 3 75s, clamming down?
« Last Edit: July 07, 2014, 11:03:58 PM by VeeSix »
1985 Alfa Romeo GTV6 V6 2.5 12V 
1986 Alfa Romeo 90 V6 2.5 12V
1990 Alfa Romeo 75 V6 3.0 12V Potenziata
1990 Alfa Romeo 164 V6 3.0 12V Zender
1991 Alfa Romeo 164 V6 3.0 12V QV
1992 Alfa Romeo 164 V6 3.0 12V QV


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Re: Project car - 1989 75 3.0 V6
« Reply #298 on: July 13, 2014, 12:52:49 PM »
@ DV: cheers :) . I still haven't had a chance to attempt retrimming with new headlining material.

@ VeeSix: well spotted. The red 'red line' has indeed faded. Are most cars like this now? I do plan to freshen it up, probably by carefully masking and spraying. I have some 'clear red' spray paint, though it may have clogged up by now.

Yes, I've read that earlier Oz-spec 75s have the trip computer instead of the plain clock. I thought about retrofitting, but it's not just wiring, and requires various sensors (eg: fuel flow, external temperature sensor) and control unit, from looking at the workshop manual. They are not features I particularly want, so I decided it's not worth the effort. But if you have the complete 'set', I'd give it more thought!

I've continued working on the dashboard area. Slow going, particularly cleaning everything, which had accumulated 25 years of grime. But one major task nearly completed was cleaning out the HVAC (heater/ventilation/air conditioning) unit.

Firstly, I removed the main dashboard after removing all attachments.

The centre and side air vents were levered-out.

To remove the cigarette lighter, the large rear 'ring nut' unscrewed, allowing it to come apart and slide out the front after unplugging. The backlight globe should be easy to change to an LED.

A cover trim unscrewed from the dashboard on the left. Attached to it was the ARC unit. A vacant area beside this is for a 'Performance Gauge' unit fitted to some cars in some markets. The ARC unit had seven plugs!

In the centre, the HVAC controls were attached by two screws.

The three dials and two knobs had various attachments: air flow distribution dial (left) was attached to a cable; heat control dial (centre) was attached to another cable; AC dial (right) was fitted to a thermostat unit, screwed to the back; air recirculation knob and fan speed knob were connected to spade terminal wires.

On the right side of the dash, the main fuse board sat behind a hinged door. The hinge pins on either side were spring loaded, and retracted for removal.

A single screw secured the fuse board. Once released, it could be manoeuvred behind.

Above, a nut secured the central locking module. The module was accessible through the hole for the small storage bin.

The protruding ignition barrel prevented easy removal of the dashboard. After removing the securing bolt, it unplugged and slid out from the steering column.

Now, only fives screws held the dashboard in position, though it was supported by two large brackets on the firewall. Two screws on the left (though one was missing!), two under the demister grill, and one on the right.

Dashboard being removed. Two support brackets provided the main attachment points.

But not so easy! Multiple wiring looms crossed behind, sandwiched between the back and the demister air duct. The duct required removal to release the wiring. Rather than screws, the duct was riveted in place; a little awkward to reach with a drill and side cutters. (I had to clean the windscreen to take the second photo through the glass!  :P )

Hurrah! Dashboard removed. Oh, the wiring!

A-pillar trims unclipped, and wiring re-secured using Dynamat sound deadener strips.

Finally, I could start the process of inspection, cleaning, repairs and modifications/upgrades!

Beginning on the left, I connected the main 0ga powerwire from the engine bay.

A Stinger T-distribution block (SPD512) was attached to the wire and screwed to the firewall. Stinger's 'Hyper Twist' wiring is indeed very flexible and had no trouble bending into position.

Decided to add another firewall grommet; this one a smaller 3ga version (Stinger PG12). Through it, I will pass some alarm wiring, and want to add a couple more senders and gauges (which I'll keep secret for now!). With the dashboard removed, easy access to drill a new (22mm) hole for fitment; bare metal edge protected with Cold Gal Primer paint.

Grommet fitted with some silicone sealant. New length of 0ga wire connected to the distribution block, and split conduit tubing for additional protection against cuts.

Appropriate time to add speaker wiring for the future stereo system. Two lengths required each side of the car, to power the door woofers and the midrange/treble drivers, using Stinger 16ga (SHW516G). To pass into the door, the rubber protective tube in the door jam was pulled off from the car exposing the existing wires. Then the new speaker wire was threaded alongside the existing door wiring from the cabin to the door jam. However, it was too flexible and soft to push through the rubber tube. For jobs like this, I have a length of stiffer speaker wire (purple, in photo); I pushed the stiff wire from inside the door cavity (after removing door trim) through the rubber tube. Joined both ends of the wires (new speaker wire + purple threading wire) by wrapping in tape, then pulled the stiffer purple wire back up the tube, taking the new speaker wire with it.

The second length of speaker wire was not for the door, so placed in the footwell area. The two wires and the 0ga main powerwire were then passed along the door sills beside the existing wiring, and taped securely.

In the rear, the wires passed over the wheel arch into the boot, and were again taped into position. Two potential hazardous areas - marked 'A' and 'B' - needed protection over the metal edges. Also note the emergency boot release cable which is usually tucked beside the rear seat, required if the normal boot release cable breaks.

A: the wires passed through a hole under the rear seat. Whilst easily big enough for all the wiring, I still covered the metal edge with split conduit, and around the 0ga wire.

B: the hole behind the rear seat to the boot was also protected around the metal edge with split conduit.

Back at the footwell area, I found one 'burnt out' connection: black wire, 15-pin plug. This was the plug for the wires running along the left side of the car to the rear door and rear of the car. Scouring the wiring diagrams in the workshop manual, I determined this to be the G73b plug, and wire in position 3, for the rear demister. It's unclear why it overheated, but I presume a fair amount of current flows through this wire.

I cut the wires and re-terminate with crimp-on bullet terminals. Plus, I'll later divert the wire from the rear demister to a relay, converting to a low-current wire, and will install thicker wire from near the battery (which will be in the boot, remember) via the relay.

Last inspection job on the left side was behind the protective shield in the footwell for the fuel injection control unit. I wasn't surprised to find only two of the three nuts held the shield in position; the third was loose on the floor under the carpet! I gave the shield and the footwell area a clean, then refitted it with all three nuts.

« Last Edit: September 27, 2020, 05:18:51 AM by shiny_car »
Giulietta QV TCT . 1.75 TBi . Magnesio Grey - Black
GT . 3.2 V6 . Q2 . Kyalami Black - Red
75 . 3.0 V6 . Alfa Red - Grey


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Re: Project car - 1989 75 3.0 V6
« Reply #299 on: July 13, 2014, 12:53:27 PM »
Now, to the HVAC unit in the middle. Quite interesting to dismantle and inspect the design, to understand how it all works. Plus, to see how much debris became trapped inside!  :o

Removed the side air vent ducts, which were secured to brackets near each end, and pulled from the outlets on the main unit.

Most of the foam gaskets/seals were perished, and simply crumbled when touched. Only the top seal - to the fresh air inlet under the windscreen - remained in good condition, and must be a different type of foam.

The HVAC unit unbolted from front brackets on each side, then pulled away from the firewall, releasing tabs slotted into two other brackets behind.

I left the unit attached on the right side by the four hoses: coolant hoses to/from the heater core, and AC hoses to/from the evaporator. There remained adequate space to work on the unit.

The heater core fluid tap is opened/closed by cable, via the control dial. There is a thin copper probe (visible in other photos below) passing to the surface of the heater core; apparently, when the engine is cold and the heater dial set to the off position, the tap is less than 100% closed, allowing coolant to trickle through the heater core, presumably to prevent stagnation. As the engine and coolant warms, the probe also warms, conducting heat to activate a thermal spring inside the tap to completely close it off. True, I read it somewhere!  :P

Lowering the unit provided a clear view and access to the rusted air inlet vent above. I previously repaired the other side of the vent when working in the engine bay, and riveted mesh to the opening to prevent leaves and debris entering. Additional repairs will be performed before the HVAC unit is re-attached.

There are four main pieces to the casing: top cover, lower section, sandwiching a fan cover between, and a front piece. They are screwed together around the edge, plus five clips at the front.

The main screws and clips were removed. The air distribution shutters were attached/hinged to the top cover; their cable and levers were attached to the fan cover underneath. After unclipping the hinge pins, the top cover was released.

A large volume of leaves and debris was found around the fan.

The fan cover was removed, and all the debris sucked away with a vacuum cleaner.

Then the fan unit unscrewed, disconnected, and removed. Time was spent cleaning the lower housing.

Two screws secured the front cover underneath. The cover was removed, after pulling the tip of the AC thermostat probe from between the fins of the heater core. The probe was pulled out through the hole at the base of the cover.

The fan recesses were cleaned. There was a protective mesh cover on the left side, covering the resistor coils that alter the fan speed. They of course become very hot (low + medium speeds), so in this location the fan blows air over them for cooling. I could lift the heater core and evaporator partially clear of the housing. Plenty more fine debris found underneath, and caught amongst the fins, which I blew free using compressed air. New self-adhesive foam strips were applied to the sides of the heater core and evaporator; these seal against the plastic housing to prevent air flowing around the sides.

Through the gap under the heater core and evaporator, a close view of the mesh, now cleaned. The mesh was plastic-welded in position, front and back. I used a flat blade screwdriver to break the front join and push the mesh aside to clean inside. This was not the proper method to access the resistors; they were accessed from underneath. After cleaning, the mesh was re-secured by melting the plastic again using a butane-heated hot knife.

From underneath the HVAC unit, the resistor board was secured by a clip, and attached to four wires. Adjacent was the hose (detached, in photo) to drain condensation that accumulates on the AC evaporator.

There are three fan speeds. Low speed is generated by power passing through a higher-resistance coil (thinner wire, more windings), resulting in low voltage. Medium speed is generated by power passing through a lower-resistance coil (thicker wire, less windings). Full speed is generated by allowing power to pass directly to the fan without resistance, via the 'straight bar'.

The fan unit comprised the motor and two 'squirrel cage' centrifugal fans. I presume the small metal clips attached to each fan function as balancing weights. The fans were pulled off the spindle for cleaning. A very small amount of engine oil was applied to the solid bearings for lubrication.

After cleaning the fans, they were re-attached, and the unit refitted to the HVAC housing. The back of the metal bracket slid into a slot in the housing, and the front secured with a single small screw. Impossible to reverse the polarity of the wires connected to the motor; one had a male spade terminal, the other female.

The fan cover held the air flow distribution shutters via cable and levers. Two shutters shared the single hinge, and were spring loaded against each other.

These were cleaned, and new self-adhesive foam strips applied to the shutters.

The fan cover secured to the lower housing by a single screw. Though, when the top cover was fitted, screws also held the fan cover in position around the edge. Foam strips were applied along the top of the heater core and evaporator, to seal against the fan cover.

Now the top cover. At the front was the air outlet to the windscreen demister vents; at the top was the fresh air inlet; at the rear was a motor to move the air recirculation flap. From underneath, you can see the screw holes around the edge.

The recirculation flap and motor cover were removed and cleaned. The flap had a vinyl cover, originally over a thin layer of foam, which had perished, leaving the cover loose. New foam was applied, then the vinyl cover glued in place with contact adhesive.

Top cover cleaned, and new foam applied around the outlet joining with the demister vent. Air recirculation flap refitted and attached to the motor.

One of the plastic tabs on the side of the top cover was broken; the tab slots into the support on the firewall. Using some scrap 3mm aluminium (the holes serve no purpose here; they were previously drilled), I fashioned a replacement piece, and trimmed the excess plastic for fitment. The aluminium was fastened by bolt and nut. The motor cover was riveted back in position.

Before refitting the top cover, I needed to fix the circular recirculation air inlet vents. Each vent was meant to have two swinging shutters, but three were missing and the remaining shutter was warped. I was unable to readily source replacements in good condition, but (member) VeeSix offered a pair from an Alfa Romeo 90 which are higher quality. Thanks David!

These were smaller in overall diameter, so not a drop-in replacement. They otherwise seem similar in design, with two shutters each, that swing open when air is drawn through. The crossbar provides strength, but does rob cross sectional air flow. Overall, they don't allow as much flow as the original 75 versions which have no crossbar, but I doubt I will notice a problem (so long as any turbulence is not detracting).

After considering different options to fit the 90 vents, I decided to integrate the frames and shutters into the 75's circular rings. I removed the 90's protrusions with the Dremel to create flat pieces; then modified the 75's rings by cutting off the supports for the original shutters.

The 90's frames were glued to the 75's. The gap around the edge was filled with silicone.

The outer surface was sprayed with Plasti Dip Black, and the shutters refitted. Not a perfect cosmetic finish, but they will be up behind the dashboard out of sight.

By re-utilising the 75's rings, the modified inlet vents slotted straight into the housing. Each retained by a toothed clip.

The top cover was screwed back into position.

Here, I've indicated the various directions of air flow: air flowing into the HVAC can be either fresh air from above, or recirculated air from the sides and behind. Air flowing out can be via the demister vent, front/side vents, or the downward floor vents.

It took me some time (!) to comprehend where the floor air vents were, and how they received air. Firstly, there were no vents underneath where I expected; secondly, one side has the cable passing through making it appear to be...a hole for the cable, and the other has the heater tap/hoses directly underneath, seemingly obscuring air flow. Thirdly, it wasn't obvious how the air reached the vents.

With the top cover off, I've indicated how the air flows from the fan, through the evaporator and heater core, then back up over the top of the fan cover (where the shutter cable/levers are) and out the sides (in the photo, the shutter is resting in the closed position, which would normally block flow to the floor vents). The top cover encloses this route.

These photos show the difference between fresh air and recirculated air, depending on flap position. For fresh air, the flap is pulled back for direct passage to the fan.

For recirculated air, the flap blocks fresh air flow, and now opens from the rear; air flows from behind the dash to the fans. Recirculated air also enters via the side inlet vents.

During fresh air mode, some air is likely to enter via the side inlet vents. And during recirculated air mode, the workshop manual suggests 15% remains fresh air. However, with the flap closing off the fresh air inlet, I can not see how fresh air can enter; it becomes completely sealed-off. There appears to be several different versions of the HVAC unit, catering for non-AC cars and RHD vs LHD; thus, a different type probably allows 15% fresh air.

That concludes this month's update! Thanks for looking through all the photos. Next month, I endeavour to mount the HVAC back into position, and work in the area on the right side (pedals, wiring, steering column, etc).

« Last Edit: September 27, 2020, 06:06:33 AM by shiny_car »
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