Heat exchanger/exhaust leak?

[schleg79]

Over the past couple of days, my 79 SC has developed a noise that sounds like an exhaust leak originating from/around the left heat exchanger. I've tried to locate the source by hand (too much fan interference), noise, and soapy water - all to no avail. The noise does not go away after the engine is at oper. temp.

Question: I have noticed a very small gap around each exhaust "tube" as it enters the top of the heat exchangers - air does seem to escape through these gaps - anyone know if this is normal on an SC?

Also, I've compared my SC heat exchangers to a Carrera's and it appears the Carrera has a collar around the areas where the exhaust tubes enter the exchangers, sealing these gaps.

Thanks is advance.
Kevin

[Groesbeck Hurricane]

Kevin,

can you jack the rear end up and safely support it per the 101 projects book so that you can crawl underneath and investigate? I'm wondering if the exhaust studs might have broken (common issue and can be fixed with motor in the car) or if you might need to replace or tighten bolts holding the different muffler pieces together.

I'm paranoid, so this is something to check the next time you change the oil or adjust the valves: could the headstud nuts be loose or a broken stud? Mine had an exhaust leak just before I noticed that the studs were breaking. Again, I'm paranoid so this might be bad information!!!

[RoninLB]

does the exhaust pop when decelerating in gear ?

[copper]

Ronin

What would that 'pop' indicate?
Mine does that, but I know I have to readjust the timing and advance after the new points break-in and I have to machine the left flange to get a proper seal between the exchanger and muffler, as I get a fair bit of leakage even with new gaskets.

Jim

[Wayne 962]

Could be a broken head stud too...

-Wayne

[RoninLB]

Originally posted by copper

What would that 'pop' indicate?

air gets sucked in if decelerating in gear with an exhaust leak. the air & exhaust gases & heat = the bang/pop. Sometimes they can be a pia to locate.. although your's, hopefully, seems like it's only the flange.

I like those thick copper faced gaskets that Pelican sells. I also use nickel anti-seize on exhaust hardware.

[OldTee]

Have your friendly mechanic stick a CO2 probe into your heater hoses. That will tell you if you have a leak that can hurt you.

[RoninLB]

Originally posted by OldTee
Have your friendly mechanic stick a CO2 probe into your heater hoses. That will tell you if you have a leak that can hurt you.

great idea..
also another option is to stop at the local FD and ask them to sniff your heat with their CO2 gizmo they carry for gas boiler and stove "odor"calls. I'd suggest doing it after the suits went home for the day.

[schleg79]

good info all. I haven't noticed any popping. It is just sort of a "flappy" sound that goes along with the rpm. I'm praying it's just an exhaust leak and not a head stud.

Still the question: is some air escaping from the heat exchanger where the exhaust tubes enter normal or are the heat exchangers intended to be sealed?

I've found a missing barrel nut also, but I'm not banking on that being the source. Looking at the naked stud, there's solid rust - indicating the nut's been gone awhile. The sound appeared w/in 2 days time (kinda short onset for most exhaust leaks, I suspect). I'll get another nut from our host and keep my finger's crossed.

ps is the barrel nut tool required or can I make do with a long allen wrench?

[RoninLB]

Originally posted by schleg79
Still the question: is some air escaping from the heat exchanger where the exhaust tubes enter normal or are the heat exchangers intended to be sealed?

I've found a missing barrel nut also

my stock HE had a space between the tubes and shell both foreward and back.

I read that it has something to do with the heat/cold expansion/contraction of the tarts, I mean parts.

barrel nut removed must be on exhaust or you wouldn't sound so relaxed?

[schleg79]

barrel nut removed must be on exhaust or you wouldn't sound so relaxed?

the missing barrel nut is from the #2 exhaust port - stud appears to be ok. Am I foolishly relaxed?

also, thanks for the gap info; that helps.

[RoninLB]

Originally posted by schleg79

Am I foolishly relaxed?

I would think that as long as the gasket didn't blow out you'll be ok with some rust cleaner on it continuously for a few days.. keep squirting every day imo. Then the anti-seize.

[schleg79]

Ronin,
My guess is the stud has been without a barrel nut for a LONG time - I've had the car 3 mos now. The stud has a good sheen of rust covering it.

What are the hazards? Water in the exhaust port, I guess? Yes that would be bad..Maybe I'm taking this too lightly.

[copper]

I've got a co2 sniffer at work. We use it for marihuana grows...
I can grab that and test the exhaust.

Only thing is, what levels am I looking for?

Jim

[RoninLB]

Originally posted by schleg79

What are the hazards? Water in the exhaust port, I guess?

forget about water. If you blew a gasket the exhaust valve it becomes susceptible to burning. If you listen to the exhaust when it's Fully warmed up real coose to the tail pipe and you hear an inconsistant "spit" it's time for a compression test. Although I wouldn't do a valve job for a little valve toasting if compression was ok.

The prob of a blown gasket is the HE removal with old rusted nuts and studs that would probably snap off when you try to remove them. IMO it's a job for a 911 pro.. or having a real torch around for a diy job.

[RoninLB]

Originally posted by copper

I've got a co2 sniffer at work.

Only thing is, what levels am I looking for?

call the FD on the non-emergency/business phone. If you get no satisfaction I can make a call.. the FD guys spend their whole life assisting people so I gotta figure they would be very helpful.

[schleg79]

Thanks, Ronin..

[copper]

Ronin, I know what bad CO2 levels are in grows, but I can't really expect our FD to know what the proper CO2 or O2 levels in my Pcar exhaust should be.

I'll ask my mechanic about my car... I'll let the FD near it if it ever catches fire.




Jim

[RoninLB]

Originally posted by copper
, but I can't really expect our FD to know what the proper CO2 or O2 levels in my Pcar exhaust should be.

oh.. ok
I got posts scrambled.

[Gordo2]

My '83 has a broken weld on top of the catalytic converter flange (the forward one that connects to the collector). Difficult to locate since it's on top of the cat. Symptoms sound the same.

Gordo