Hi everyone. I have several Volvos, and usually post on the 140 site.
I consider myself a fairly competent mechanic, but have a simple problem that I do not understand. I make a lot of mistakes, and am probably doing something wrong. Perhaps you can help.
The exhaust gasket, specifically, the lower one that is on the bottom of the manifold. Known as the collector or doughnut gasket by some, on my 83 244 it is triangular in shape and takes 3 bolts.
I replace this gasket every 4-6 months, and cannot figure out why! I have chased the threads and always torque it in sequence, and then retighten after running hot.
The bracket that holds the exhaust up right after the connection is good, and the exhaust is not too shaky, held in properely with rubber hangers.

Why is this gasket failing so often? This will be the 4th in under 2 years. Should I switch to a special type instead of the Autozone $8 one?
Comments?

Jeremy
Oxford, MA
71 142E, 83 244, 86 245, 95 940(Wife)
--
71 142E and a yard full of 240's in Mass.

I see a lot of good ideas but one thing is not mentioned. Use NEW locknuts with your next repair attempt.

Bob,
Perhaps that is what I am missing. Also, when I dissassembled it the first time I had the car many years ago, ont of the studs was not a stud, but a bolt. So, there are 2 studs mounted in the bottom of the intake, and one bolt that goes through and tigthens to the manifold through the flange.
Should I purchase another stud and install?


Thanks,
Jeremy
--
71 142E and a yard full of 240's in Mass.

Obviously someone in the past snapped off the stud and replaced it. Hmmmm...interesting. As long as the bolt is of a size that lets you put adequate torque on its nut (ie: about the same as the studs/nuts) it will do its job, which is to clamp the two flanges together. As long as the nuts are staying torqued and not coming loose from vibration or the heating-cooling cycles, your problem is elsewhere.

I'm going to guess it's a matter of misaligned flanges (the manifold is finished at the factory with a precise machine tool) or non-smooth flanges, or the exhaust system is not hung properly and is putting a stress on the flange joint which eventually causes the leak.
--
Bob (son's 81-244GL B21F, dtr's 83-244DL B23F, 'my' 94-944 B230FD; plus grocery-getter Dodge minivan, hobbycar MGB, and numerous old motorcycles)

Aftermarket downpipe? They are not built to perfection. Got a muffler shop to install mine and the guy ran the gasket mounting surface over his grinding wheel, stating that typically they all need this. Three years later, still tight.
--
Bob (son's 81-244GL B21F, dtr's 83-244DL B23F, 'my' 94-944 B230FD; plus grocery-getter Dodge minivan, hobbycar MGB, and numerous old motorcycles)

Along with all of the excellent advice below, may I add a possibility?
Are your transmission and engine mounts in good shape? If they sag or allow too much engine movement relative to the exhaust system the forces might work on the exhaust donut.

To all who have answered, thanks for your help.

Other comments: It always seems to fail in the rear on the 'triangular side' that most faces the block.
I always remove that bracket prior to re-installing, because you have to in order for the exhaust flange to drop low enough to clear the studs in the manifold. I have inspected the faces on both mating surfaces, and see no obvious gouges or bends, but perhaps I should check using something other than 'eyeballing' it.
I have a small palm sander, perhaps trying to 'resurface' the faces using 180 grit is an idea?

Thanks again,
Jeremy
--
71 142E and a yard full of 240's in Mass.

So, looking toward the front of the car, the joint fails at roughly the 9 o'clock position?

Assemble the joint without the gasket in place. Shine a light from behind it, and look for any big openings. Take a feeler gauge (preferably one you hate) or something similar and see if it goes inside the joint at various places. This could help you determine the 'high' spots that you might need to grind down if you can't find anything obviously wrong with the rest of the components mentioned so far. A hand grinder would be good. I suspect with the amount of the misalignment or flange distortion or whatever you have, it would take a better part of your evening using 180 grit.

And FWIW, if you have any doubt about the quality of the gaskets you are using, and after going through this as often as you say you have, why not just get one from Volvo? I mean, how much more could they cost?

If all else fails rent a MIG and never worry about it again.

What type of construction is used in the AutoZone gasket? Is it steel on both sides with some sort of compreeeible core? If so, tryu spraying it with a couple of coats of Permatex Ultra Copper gasket spray before you install it. I've reused the collector gasket on later models a couple of times by using that spray.

BTW, the possibility exists that you have either a warped manifold or headpipe flange.
--
1991 245, 61k miles, looking for a 5 speed 92-93 245 cheap.

The Autozone cheap gasket is brown in material, with a small internal metal grid that does not seem cheap. It is a Fel-Pro.
I always completely remove the bracket that holds up the main exhaust prior to mating the lower exhaust manifold to the flange, so there should not be an alignment issue(I think).

Any ideas on how to discern that the headpipe or manifold is warped? Put a straightedge on it after dissassembly?

Thanks,
Jeremy
--
71 142E and a yard full of 240's in Mass.

Have you checked the manifold flange and the downpipe flange for flatness, gouges, missing material, etc. To get a good seal you must be sure that all surfaces that you are trying to join are clean and straight.

Loosen the bracket, and then tighten the two together, something is under stress.. check the torque 10/13 lbs? mine is differant than yours..
--
john,, 1985, 245:Ti, 251k mi..so.california,,,1974, 145, 230k mi. ..

I'm having the same problems on my 89 and on my 86... I can not say for sure but the next thing I try will be....loosen the bracket that holds the the exaust to the bellhousing? before thighting the manifold/ downpipe connection...I'm thinking that by not loosining it, it is holding the down pipe at a bit of an angle and not letting the gasket at the manifold get a good seat.

I have no assurence that this will work...just what I'm going to try next...that and any other good ideas that get posted in response...
Bret
--
rust free in west Texas

Well, as John posted, 10/13 lbs, I am sure that I went over this.

Especially after the second one failed. I did not use a torque wrench, because it is a real pain to get under there with a standard socket. I went "damn" tight with a 3/8 rachet.

Also, I have been always putting copper anti-sieze on the bolts.

Another thing, the gasket always seems 'burned away', rather than simply broken due to a mechanical mating problem.

How does yours fail?

Thanks,
Jeremy
--
71 142E and a yard full of 240's in Mass.

That's it..loosen the bracket, and then tighten then the two together ..check the torque 10/13 lbs? mine is differant than yours..
--
john,, 1985, 245:Ti, 251k mi..so.california,,,1974, 145, 230k mi. ..