Exhaust Leak into Heat Exchanger/s?

[RickS]

On a rather long drive - 8 hours - in 45 degree temps with the heater going after a few hours I found myself getting a little woozie. When bedding down my head felt quite strange (stranger than usual). The next day, I cracked a rear window, kept the fresh air dash vent open and blowing with minimal heat on my feet, with no ill effects.

Edit: the exchangers are stainless and 4 years old with 4.5K on them.

Is it common for there to be cracks in the exhaust to leak into the exchangers or might there be another cause?

[RickS]

Any one know the expense associated with having them x-rayed or it there a better method to determine the problem?

[ajwans]

I found a leak I couldn't see in a bike tyre by submerging it. Plug the muffler end,
keep that end uppermost and submerge the whole unit. You will see bubbles from the
fan output end if there's a leak from the exhaust pipes.

n.b. just a theory, I haven't tried this. CO is poisonous, be careful.

edit: actually I would plug all the exhaust ports as well and use a bike pump to
inject air into there.

andy

[Aldo]

Don't muffler shops use a sort of smoke/dye that they pump into
the exhaust to check for leaks?

[sithot]

Cracking was an issue in the early cars which got re-called and had them replaced.
Don't scrimp on heat exchangers. CO can render you unconscious in a matter of minutes. With enough exposure (PPM) it will kill you very quickly.

Tom

[denson]

Hi Rick:

I am having a similiar problem and wanted to share some thoughts. My 70 S has the OEM exchangers. I own the car six years and did not use the heat much during that period. When I used the heat, the cars interior would smell, not so much of exhaust gas, but of a burning oil based odor. I got headaches from it, my clothes smelled and I, too did not feel all that well. My only criticism of Porsche design is that we should not be receiving heat from a system that is so poorly designed and which can place one at risk should a small pin hole develop in a header pipe. Further, I gather in Germany they did not have traffic during that time as the system only works well at higher rpm driving. If the fan is not moving fast, you can freeze to death.

In any event, I removed the exchangers and found a small leak coming from the oil cooler (passenger side) which was entering the exchanger. I took them to a radiator repair shop and they acid dipped them to get the oil out. Thye claim that they were filthy and alot of oil came out. The only paint that came off from this washing was where there was minor rust under the original paint. I gave each exchanger two coats of a dark grey heat sensitive paint. They look great now. I have a new problem. I cannot get the acid and whatever chemicals they used to burn off fast enough. When I use the heat now, I get huge doses of burning chemicals and paint. It is super foul and intolerable.

At this point, I will wait till summer and in hopes that this stiff burns off. If not, I am buying SSI exchangers. That is if they are ever available again.

What brand are your stainless exchangers? There has to be a warranty that should protect you.

Make sure you do not have a leak issue as I did. Perhaps, it is not exhaust
gas, but oil. They should never have cracked with such little use.

Good luck

John

[tfiv]

Rick, Pilot supply shops sell little indicators you can stick on the panel that change color if the levels get too high. Most piston airplanes use the same technology for heat.