Hi guys,

First time posting here, hoping someone has had a similar problem and can point me in the right direction. I bought a 1986 Volvo 740 Turbo Wagon about 2 months ago (200k on the engine), seemed to run great aside from a small problem starting when warm. I've put about 2000 miles on it and now it has been making a horribly loud noise when I put any stress on the engine (uphill, starting from a stop, basically whenever I depress the gas pedal more than about half way down). I've also lost a considerable amount of power. The noise sounds like sort of a cross between engine knocking and a BAD exhaust problem - kind of like a go-kart. But it's quite loud and embarrassing. I don't know that much about cars so I appologize if my description is a bit off. The car idles fine when at a stop and the engine doesn't seem to be overheating. Also there is no water in the oil or oil in the coolant. Today I popped the hood and noticed that there was a freshly melted hole in the plastic timing belt cover. I am really puzzled by this. The noise seemed to start about a week or two ago and has been getting gradually worse over time. If anybody has any suggestions or can at least offer me a starting point I would appreciate it. I just bought the Chiltons manual today - I'm hoping to have a local shade-tree mechanic take a look at it tomorrow but he admittedly doesn't know a thing about volvos. Help!

 

Where is the hole in the timing belt cover?

Regards, Andrew.

 

Thanks for the quick response! The hole is next to the exhaust manifold. I took all of that off today and the gaskets were completely obliterated. I am assuming the leaking exhaust melted a hole in the timing belt cover. I replaced the 4 gaskets and put everything back together and the worse half of the noise seemed to stop. However what sounds like the TURBOCHARGER is still making a pretty annoying exhaust/popping noise. What gives? My shade-tree mechanic seems to think there is a bad gasket somewhere in between the turbo and head or in between the turbo and the cat, or both. Problem is I can't find these gaskets ANYWHERE online, nor do I know what they're called. Who knows, this guy could be wrong altogether - anyone have any idea why a Garret turbo charger on an 86 740 Turbo would be making a bad exhaust noise? If he is right, where can I find these gaskets he's talking about? I Called the local Volvo dealers parts department and they only have some oil-line gasket and some other crush-washer or something. I don't think either of those parts are what he's looking for - but I could be wrong. Also, I think the EGR valve is bad. Can't seem to find one of those for an 86 either.

 

Aha, that confirmed my suspicions. Be sure to retorque your exhaust manifold after a few heat cycles.
It is entirely likely your turbo flange is leaking, I think they are a stainles steel shim type gasket, so just try tightening the nuts holding the turbo on.
Also suspect the exhaust downpipe where it bolts to teh turbine housing, my turbo loosens that joint about every six months.

Regards, Andrew.

 

I too am looking for that gasket. One mechanic told me their is no gasket there(between the turbo and manifold) but I find that hard to believe.
Please if you find a part number let the post know!
Thanks Reggie

 

Assuming you have a stock T3 Garrett turbo, there is no gasket ok? The exhaust manifold has a recessed circle and the turbo mounting flange has a raised circular portion. The fit together and once bolted...do not leak. Gaskets near turbos wouldn't last long as they would burn up. Aft of the turbo, where the exhaust exits, there is conical three bolt exhaust fitting. There is no gasket here either, but you can get leaks from time to time. The torque of the motor combined with less than new motor mounts causes the copper lock nuts to back off a bit. This is especially true if the exhaust has been replaced and the installer neglected to replace the exhaust holder that mounts to the bell housing.

 

Thanks for getting me up to speed on the gasket or lack of one swiftjustice44. What should I torque the four bolts holding the turbo to manifold to? thanks for all the info. Reggie