Author Topic: 3.0 Help Please  (Read 18420 times)

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LukeC

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Re: 3.0 Help Please
« Reply #75 on: November 28, 2017, 07:24:13 PM »
Nevertheless, I will explain how this thing works and the correct procedure in setting it up for anyone interested (and why the procedure is critical).

I whipped up a tool this morning (through the fog of jetlag from flying back from France) to send to Andrew, but he seemed confident to solve the issue.

You first have to understand the device: It is actually a tensioner/detensioner! There is a hydraulic piston operated by engine oil pressure and three springs. Number 1 spring is a compression spring and sits behind the cast piece and is there only for the initial setting up. Number 2 spring is a compression spring internal in above the hydraulic piston (below the aluminium cap). Number 3 is a relatively weak tension spring acting on the steel lever (and is covered by a black plastic sleeve).

The set-up pin (pictured with a workshop sketch) is shown below. It is inserted into the unit as shown to compress spring 2 to a pre-set amount (normally before the unit is fitted back to the engine as it should be re-kitted when belt changes are performed. The unit is mounted on the engine and rotated so spring 1 is compressed and unit withdrawn with nuts nipped up (and belt can be fitted). The belt is fitted with all the timing marks in the right places. The nuts are then loosened so that spring 1 can act on the unit and place some tension on the belt.

This part is critical: The engine must be turned at least two full cycles (4 rotations) slowly and ensuring that the engine does not turn backwards at all. When the engine is back at TDC (this position we know the cams will maintain a static position), and the timing marks all lined up, the two nuts are now tightened. Spring 1s job is over! Now the pin is withdrawn and spring 2 can act through the piston and add more tension to the belt. At this time, the engine can be safely be turned anticlockwise safely (if you wanted to).

When the engine starts, idles and stops: i.e. oil pressure is low, the pressure from spring 2 maintains high belt tension. This is because of the cams tend to flip/flop over their lobes and without this tension the belt may jump a tooth (remember, this was early cambelt design and the teeth were not as aggressive as later engines). As the engine revs climb, so does oil pressure and the piston withdraws and reduces the tension on the belt. Now, only spring 3 is applying tension to the belt. High tension is not required as cam inertia will overcome the tendency to flip/flop as with low engine speeds.

The other thing to remember, is the engines do not stop dead when turned off. They will often do a revolution or two, come up against a compression stroke and rotate backwards a bit. This extra tension added at low oil pressure times guards against this.

The stepped pin set-up is necessary to ensure the relationship between the hydraulic piston high tension at low engine speeds transition to low tension is correct. One may get is right without, but there is only on way to make sure it is perfect as Mr Alfa wanted.

Complex: yes. Old fashioned: yes. Better ways now: yes (like the mechanical tensioner available) But so Italian!

Luke Clayton

qvae.com.au

LukeC

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Re: 3.0 Help Please
« Reply #76 on: November 28, 2017, 07:27:39 PM »
The tool (under 10 minutes on a lathe starting with a 10 mm bolt - LOBO of course!):
Luke Clayton

qvae.com.au

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Re: 3.0 Help Please
« Reply #77 on: November 28, 2017, 09:07:01 PM »
Thank you for the detailed description of how the tensioner works, definitely learnt something!

Again thanks for going through the trouble to even make a tool! However I am confident I have everything under control. Took the car out for a drive tonight, being careful to watch temps and not to rev the motor unnecessarily. Happy to report that everything is running fine with no issues at all.

There are no oil or coolant leaks and no cross contamination in the oil or coolant, which means the head gasket is installed correctly.

I have to say, the car is completely different to drive. I have found it to be much smoother and actually sound different as well. It has got a lower note to the exhaust and seems to idle more calmly than before. Overall I'm very happy with the end result.

Thank you everyone for contributing to the thread and helping me along the process, time to go out and enjoy the car.

See you all at Spettacolo!

Cheers, Andrew.
Present:
-1992 164Q
-1993 Hilux Surf
-1994 VR Calais

Past:
-2006 159 2.4 Ti

V AR 164

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Re: 3.0 Help Please
« Reply #78 on: November 28, 2017, 09:12:22 PM »


Quick pic of the finished engine bay. Took alot of time cleaning everything and painting things to make it look presentable.

Andrew.
Present:
-1992 164Q
-1993 Hilux Surf
-1994 VR Calais

Past:
-2006 159 2.4 Ti

ACE

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Re: 3.0 Help Please
« Reply #79 on: November 28, 2017, 09:18:27 PM »
Excellent work Andrew.
Well done.
And it looks very nice too!

bonno

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Re: 3.0 Help Please
« Reply #80 on: November 28, 2017, 09:38:38 PM »
Good job Andrew.   :)
now
83 Alfetta GTV
05 156 JTS manual
past
00 156 selespeed
72 1750 GTV

Mick A

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Re: 3.0 Help Please
« Reply #81 on: November 28, 2017, 11:27:00 PM »
Well done mate! See you on Sunday.

stustustu123

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Re: 3.0 Help Please
« Reply #82 on: November 29, 2017, 10:41:48 PM »
Wow, great result Andrew, amazingly clean and well presented engine bay you have there too.  8)
2007 159 SW 2.4 JTDM
1993 164 Super
Past:
1994 164 Super (Blue)
1992 164Q (Black)
1989 164 (White)
1988 75 3.0 V6
1983 Sud Ti

sportiva

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Re: 3.0 Help Please
« Reply #83 on: December 02, 2017, 06:35:27 PM »
Excellent work Andrew. Good on you for having a go.
3.0 GTV6 Fiat Free
156JTS

ex
75 2.5
2.0 Alfetta Sportiva #22
1.8 Alfetta
1.2 alfasud
2 75 parted out
15 alfettas parted
10 gtv parted
5 alfasuds parted
156 sele

Rising Sun

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Re: 3.0 Help Please
« Reply #84 on: December 02, 2017, 09:33:42 PM »
Hey Andrew, I just read your entire thread here, all 6 pages. Looks like you got some good advice on here and in person and its wonderful that you actually took the time and effort to get this all sorted yourself. Well done! Its so encouraging to see good young guys like yourself using the resources around you to work things out rather than just giving up. When I did my apprenticeship, I learned that a good mechanic doesnt necessarily know everything, but should know where to get the correct information. Again, well done - great effort!