Another day another problem...

[75Guy]

You know what? I am really glad that this website exists and I have to thank anyone I haven't yet thanked for helping me out in the past. Cheers guys, your knowlege and insight has helped me out greatly this last few weeks.

Okay enough gushing, now on to the new problem.

I have a grinding/rattling noise under very specific conditions. It definitely does not affect the operation of the brakes, clutch and steering. In terms of mechanics the car goes and handles brilliantly. If anything it changes gear BETTER than before...

It grinds when driving and parked when the rpm is between 1000-2000 rpm. Clutch in or out, doesn't really matter but at the friction point it does tend to rattle and grind more. Higher than that and it goes silent, at idle it is also silent. Interestingly if I hit the gas hard then take my foot off there is noise as well.

It seems to be getting worse. It started out as a minor grinding noise and now it sounds deeper...

I have checked and replaced all swaybar linkages, have inspected upper mounts for front suspension and so on. Nothing there. Checked the brakes just to be sure and there is no sign of metal on metal contact - no grooves, shiny metal or anything. Its not the engine mounts. I tried lifting the engine a bit and they seem a-ok.

What I have found was a broken exhaust mount on the catalytic convertor but when it was removed there was no change to the noise produced.

I am starting to think its the driveshaft because by changing the load on the engine and by using the clutch I can make the noise occur. To me that sounds like the load is changing on the driveshaft and something is worn causing it to be unbalanced. I really hope its not though because that would really be a problem I can't deal with right now - how much does a set of guibos set you back these days anyhow?  

So what am I missing? Am I on the right track? Or should I go to plan b: petrol + matches.

I'm thinking after this is solved the car will be sold and I will get a 'Sud.

[alfagtv152]

Hi there,
If it does it whether you are moving or not,clutch in or out and at specific revs then I would say it is the tail shaft,probably doughnuts.
Cheers
Andrew

[75Guy]

Yep thats exactly what I am thinking. Sigh.

Oh well I better go and work out where to buy some doughnuts and replace the exhaust while I am at it... There goes my weekend.

[alfagtv152]

Don't forget to check the center bearing and mount,also make sure the doughnuts all centre properly on what they are supposed to,sometimes worn shafts and bearings cause things to run out.
Have a good weekend!,
Cheers
Andrew

[75Guy]

Good news! (kinda)

Its the rear engine mount! (most likely)

Should be easily fixed by monday   

[Typhoon90]

Interesting. My 90 has started making a rattling exhaust kind of noise when idling in the shed, sound coming from driveshaft, I know the rear engine mount is squishy, might look further.

Regards, Andrew.

[MD]

75Guy

A couple of tips for ya.

To confirm that it is your rear engine mount bush, be a cheapskate and cut off a couple of pieces of old heater hose and wedge them into the voids around the centre fixing bracket to isolate the metals. Do a test drive. If that cures it, you have correctly identified the problem.

If indeed that is the problem then you got 2 choices

Fit a new mounting bush by pressing it in and out which is problematic or,
Leave the old bush in place. If you leave it in place:-

Centralise the metal stay in the middle by placing a small prop under it to keep it there eg, a nut. (You will need to jack the engine to do this).
Get a can of carbie cleaner, completely degrease the bush and surrounds.
Get a cratridge of Sikaflex construction polyurethane adhesive.
With a cleaned bush area and the stay propped, inject the polyurethane into the voids from both sides filling the entire voids.
Scrape off any excess. Leave it set for 48 hours and don't use the car.
You now have a new rear engine mount without the dramas of remove and replace.

Dig me pigmy?

[75Guy]

Thanks for that tip, however I think I will still go for new/re-manufactured parts.

Turns out I have a few problems:

a) worn engine mount - this led to increased engine movement which led to

b) blown center mount which led to

c) disintegrated front doughnut which led to

d) me being out of pocket

Oh well, its getting fixed by the infamous Mr Caplice because I am too chicken busy to touch the driveshaft.

[Duk]

It constantly 'amuses' me how crap Alfa Romeo rubber components are  .
I mean, who else makes engine, gearbox and tailshaft components that are so failure prone???
Yes they are all getting old, but still.......... "I expect results, not excuses!" 

[JOHN G]

You are much better off breaking a $100 doughnut than destroying a gearbox.