Heat exchanger exhaust leak

mackskibum · 03-09-2008, 04:46 PM

Hi gang. I am chasing an exhaust leak on my '85 3.2. Leak is between the flange and tube on #5- no leak from the outside of the gasket. Leak appears to be in an area not sealed by a gasket. Do I need a replacement exchanger?

Thanks

mackskibum · 03-10-2008, 05:26 PM

Bump... I am going to take one more shot at describing the leak...

The leak shows on the side of the #5 down pipe (part of the exchanger that drops from the engine into the main part of the manifold), and on the engine side (top) of the heat exchanger.

There was no apparent leak through the gasket- the edges of the mating flanges are clean- it seems to be coming from between the flange and the down pipe. Is there a weld that holds the flange to the down pipe? I was under the assumption that the HE was one piece, and the flanges are a sealed attachment...

Can I repair by welding the flange to the down pipe?

Thanks

Dave

richde · 03-10-2008, 10:11 PM

To be absolutely sure it could be welded, you'd have to remove the HE. Depends if it's a crack or corrosion. I assume it's outside of the HE tin so it doesn't fill the cabin full of exhaust fumes with the heat on.

TWork · 03-10-2008, 10:43 PM

I'm not sure I follow what you mean about the flange being a "sealed attachment." My recollection when I pulled the HXs off my SC was that the flange was welded onto the HX. If you had a leak there, I can't see why you couldn't lay down a fresh weld bead to seal any leak. Probably worth pulling the off to take a look.

mackskibum · 03-12-2008, 04:53 AM

Thanks for the replies. The HX is off- I can not see any cracks in the unit.

Richde- it is outside the ducting- it is leaking right at the flange.

Twork- you hit on the reason for my question- on the 3.2, there are tube extensions that actually project into the exhaust port on the cylinder head. I believe that to be different than the 3.0 on your SC. The flange is approx. 1/2" from the end of this tube, and I can not see a weld that holdcs it in place either at the top or bottom of the flange. The leak is actually between the flange and the HX tube- the gasket does not seal this area. There are no leaks as a result of the gasket- the flange to head interface is fine.

If I can weld the bottom of the flange without issue, I think I can solve the problem. The reason for the question is I am not sure if the flanges should be able to move or not- some vehicles allow movement to make up for irregularities. All of mine are in a fixed place due to corrosion or by design- I don't know which.

What say you??

Dave