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Discussion Starter · #1 ·
Hi,

I have a 1992 n/a 2.0 litre car with a manual transmission that has a recurring problem with exhaust leaking out from the connection between the front pipe and the catalytic converter. I made a new bronze gasket on the lathe, and it worked (sort of) for a few years, but now I'm stumped. Last time we took it apart and packed the joint with cement, it lasted less than a week.

I suspect that the problem is due to worn engine mounts, allowing the engine to move more than the exhaust system was designed for. The engine mounts LOOK good, though. This car isn't worth putting new engine mounts into, so if that's the problem, I still need another fix. Or ... how many hours would that job take?

Here's the question: Has anyone managed to find a good fix for this problem? Has anyone found a way of modifying their system with (for example) flex pipes?

:-J
Jørgen
 

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I've never had the problem on any of my cars Jørgen, turbo and NA. I suspect you may be right and there may be too much movement due to worn mounts or maybe from cat back the system is too rigid and the hangers don't allow enough movement. I find it difficult to understand how it can develop a leak if it's bolted up tight on the olive. Flexible joint pieces are not on my list of favourites. They are often more trouble than they are worth and, in my experience, always end up leaking. Can you rock the engine much by hand? If so, the easiest way may be to sort the mounts. Don't forget the front mount which can lift if not secure.

Paul
 

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Discussion Starter · #3 ·
Thanks, Paul. The first time I got the problem was about 7 years ago (when it was my daily driver), and I've spent hours and hours and hours working on it. I've even swapped the front pipe. Every 2 years or so I've had to redo it. The situation is kind of urgent because my daughter (who drives it) is going back to college, and because the car needs to be approved (2-year safety inspection) some time in the next 10 days.

I've no experience with flex pipes myself, and I'm not even sure it's possible to install a piece between where the O2 sensor is and where the cat. starts.

I've opened the hood and observed how much the engine twists when I let the clutch halfway out in reverse and 1st (my daughter helped me). I'll do the same test to one of my better cars tonight, and compare the amount of movement. That should tell me whether there's something abnormal about the engine mounts. But ... we don't have time for that kind of job before she leaves for college, and this is a car with a rust problem.
 

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The more I think about it, if it is a mount/s, it's more likely to be the front mount, which lifts under acceleration. More so in the lower gears. This would put tension on the problem joint. Fortunately the front mount is fairly easy to inspect and replace.
 

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If it is front mount, you can always do something like "Mason-Dostie Manoeuvre" (named after a pair of Saab enthusiasts)

Basically you see where there is the limiting bracket and rubber, and you shove something in there more to keep it tighter. You don't really want a loose front mount, one day it will break the distributor cap off.

http://www.webmiscellany.net/saab/md.html
 

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If it is front mount, you can always do something like "Mason-Dostie Manoeuvre" (named after a pair of Saab enthusiasts)

Basically you see where there is the limiting bracket and rubber, and you shove something in there more to keep it tighter. You don't really want a loose front mount, one day it will break the distributor cap off.

http://www.webmiscellany.net/saab/md.html
I don't think Jørgen has that type of front mount with the top limiting bracket. It's not a turbo it's an NA.
 

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Discussion Starter · #8 ·
I've never seen copper RTV sealant in the shops, but will make the round of the shops tomorrow, and see what they have. If all else fails, I have a small bag of asbestos twine that might be useful.

I didn't have time to check out the engine mounts today. Daughter got a temp job offer that was too good to be true (for a cash-strapped college student) and rushed off with the car. Now she and I will only have one evening together for fixing the problem - so no time for doing anything serious to the engine mounts.

Below are two pictures: One from the paint job we did to the car 2 years ago, and one of the type of front engine mount we have.




 
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