[AT] no exhaust gasket?

[Steve W.]

John Hall wrote:
> Not tractor but old combine. My Deere 3300 with a 219 gas engine has an 
> exhaust leak. It is where the exhaust pipe attaches to the manifold. 
> This is accomplished by means of a very heavy cast elbow bolted directly 
> to the manifold with 3 bolts. There was no sign of any gasket. Me nor 
> the parts guys at Deere can find a gasket in either the engine or the 
> combine parts books. There best parts guy at the local store (I highly 
> respect his ability) suggested there wasn't a gasket used. I cleaned and 
> checked the surfaces and they are relatively flat, within .005" or so. 
> What do you guys think about the no gasket used possibilty? I have a 
> friend that used to do heavy truck repairs. He says NAPA has an exhaust 
> sealer that is very tar like. He said they were able to seal some 
> exhaust leaks with it--used it where the flare of the pipe clamped to 
> the manifold. He also said some Chevrolets were put together with no 
> exhaust manifold gasket--I think this was figured out by mechanics, not 
> the factory. This is all new to me, Every exhaust I dealt with had a 
> gasket. What do you guys think?
> 
> John Hall
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> 

Quite a few items like that are put together without a seal, just 
machined very flat (within .0005-.001 usually). Works fine until the 
parts get worn, pitted or damaged. Then you either replace the pieces, 
repair them by facing them on a mill or similar or add a gasket.

As this was already leaking I would say a gasket should do the trick. 
(unless you have a way to machine both surfaces again).
I've used a few exhaust sealers over the years for those areas that you 
either cannot get a correct gasket or in an area where a gasket just 
won't work. The two that have worked the best were good furnace cement 
(for flanges such as yours) and "muffler patch" aka water glass paste. 
The latter works good on flanges IF you use the type with the patch 
material. Just cut it to the shape of a gasket, apply the paste, bolt it 
down tight and start the engine to cure it. Let it cool down and check 
the bolts. Stuff lasted for over 5 years on a GM truck that had 
manifolds that were VERY pitted and wouldn't seal with normal gaskets.

-- 
Steve W.