Heat exchanger loose...

[graups]

I'm not sure what the various parts are called, but the outside heat carrying shroud that encloses the heat exchanger is loose on the internal parts that carry the exhaust. I assume these should be connected and solid to avoid rattles when the car is running. Is this something I can just get someone to weld back together? I have them off the car while I rebuild the engine.

Thanks,
scott.

[GeorgeRud]

I was told you should not weld the outer envelope to the inner tubes as that can cause a crack to form at that point. I've never done it, but I wonder if some JB Weld might hold up under the heat? Otherwise, you could try to crimp the outer envelope a bit tighter to the tubes.

If you're running older heat exchangers, it also may help to keep a small, battery operated carbon monoxide detector in the car. Otherwise, general aviation suppliers have detectors that pilots use, though I like a good, load alarm. Even the SSI heat exchangers are starting to get old and the pipes could crack. Better be safe than sorry!

[earossi]

You did not mention the age or materials of construction in your heat exchangers. If they are older and made of carbon steel, then the looseness/rattle may be the product of severe metal loss due to corrosion. If this is the case, you should consider replacing the exchangers with SSI or ones that are not showing signs of failure.

Also, if there is severe corrosion that has holed through on the jackets, you can pull all types of road fumes into your cabin, including carbon monoxide, which is another reason to assure yourself that you have mechanically sound exchangers.

I would not attempt to use JB Weld to make repairs to heat exchangers. Your headers, which are on the interior of the heat exchanges can run temperatures approaching 800-900 degrees. Since most epoxy is toast at less than 500 degrees, the use of JB Weld would be a waste of time and material.

Just my 2c.

[GeorgeRud]

I did check the JB Weld site, and they do say that 500 degrees is the max, so no go on that idea!

You could always cut off the outer envelopes, block off the cooling ducts from the engine and to the body, and do without heat. The best option would be to simply replace them $$$$$$$$.

[graups]

Sorry about that. They are original equipment on an 83 sc. Visually, they look ok to me, just a bit loose.

[earossi]

In the picture you posted, it appears that you have lost part of the shroud due to corrosion. The problem is that the shrouds are originally meant to be an enclosed cavity in which air flows over the exhaust headers for heat transfer. The heated air is either ducted into the cabin of the car when heat is required, or it is ducted to atmosphere during warm weather. When you put "holes" through the shroud (where corrosion has destroyed the shroud), you have an opportunity to induct air on the bottom of the car into the cabin of your car. That is a safety issue. The shrouds usually rust away at the edges where the shroud is closely fitted to the exhaust header. Localized heat transfer at that interface exacerbates oxidation of the shroud material.

Your other option is to block off the heater ducts so that no air can enter the cabin from the heat exchangers. You can then cut off the shrouds to eliminate the rattling that was an issue for you(mentioned in your original post).

[graups]

Originally Posted by earossi

In the picture you posted, it appears that you have lost part of the shroud due to corrosion.

Which part are you referring to? Near the three pipes?

Thanks,
scott.

[GeorgeRud]

That's the spot. From that view, I'd say that they're shot and are ready for replacement if you need heat.

[Aurel]

It is very easy to find used replacements for cheap, since many owners have upgraded to SSIs and have the original ones sitting in their garage. I am one of them .