Phoenix79

Had my daily check up done on Phoenix *1979* 2 weeks ago and found out I had a leaking gasket on my exhaust manifold. The car drove fine except for the loss of power and a faint clicking sound due to the gasket leak. Now the car has to work hard when I start it up in the morning at idle. After say a short drive and the engine warms up, the car idles fine except for a louder clicking sound on both sides. I'm assuming both gaskets are now leaking and is causing the trouble. Will any other problems occur with the gaskets leaking. I'm going to fix them tomorrow or the day after but I may have to drive Phoenix to work today.

Tom73

I would try tightening the manifold bolts to make sure things are tight. That may cure your problem.

By the way, chevy did not use gaskets on the exhaust mainfolds, just a metal to metal fit.

tom...

R. Bruno

Really? They don't have those ceramic donuts?

1LE

Yes there are donuts betwen the manifold and the exhaust pipe.

Phoenix79

See I thought there were gaskets. The shop had said my gaskets were leaking and Ecklers sells intake manifold gaskets for stock 1979s. Is this a hard job to do on your own?

Jughead

I removed my exhaust manifolds from my '70 and two '89 350's and there were no exhaust manifold gaskets.

rainman69

So, speaking of the donuts...my car eats them...about a month or two after I install one, it's completely disintegrated and not sealing good...

??? :confused: :smash:

R. Bruno

Duh- My mistake. I see now we are talking about manifold gaskets not exhaust pipes.

Dalannex

Is your car running lean? That would cause the manifold to get hot enough that it could burn the gaskets out.

WATTAC

If the question is really exhaust manifold to engine "gaskets" then I know of at least two results from leaks. Neither are good. First, FIRE. The leaks can burn through anything in their path, fuel lines, wires, etc. Second, if left unattended the leaks will "cut" a path in the exhaust manifold mating surface, ruining any chance of sealing it later.

And yes there were no gaskets from the factory. And that's fine if both surfaces are new and very flat, just like they were from the factory. Once the manifold gets hot it distorts and sealing gets harder to impossible. Best to use some kind of gasket/sealer, unless you go to the trouble of machining both surfaces.

As far as the donuts, and eating them, I'd check for bad mating surfaces in the manifold/pipe. Any slight leaks will burn through the gasket/manifold/pipe just like it will up by the engine/manifold.

Andy

Phoenix79

Hmm so does that mean a C3 owner would have to eventually buy a new exhaust manifold every so many years? Is there a fix that'll last the length of the car? From what the shop said, my C3 is in near perfect condition except for the exhaust problems. I'm a humble 18yr old college student who happens to be stuck with a beautiful car as a daily driver for the next few years *I'm not complaining one bit, I love the C3s and I love my car*. So fixing the gasket will only stand as a temporary fix? If I were to replace and reseal the gasket myself, how difficult would you say it would be?

Jughead

I'd try to torque the bolts first. Get a torque wrench and I believe they're tightened to 20-25 ftlb. I'm getting a tick-tick sound on my '89 Sub now. I'm gonna try torqueing the bolts first.

No, the exhaust manifold should normally last the life of the engine.

UKPaul

My P. side manifold has a slight leak as well (another winter job :) ). As for the effects of a manifold leak, my experience is with my Bike (things like this are more noticeable as the engine isn't rubber mounted):
1) The cylinder(s) with the manifold leak seem to run lean
2) Popping in the exhaust on shutdown (but I like that ;) )
3) Engine tends to run rough (especially noticeable on a twin but not good for any engine)
4) Loss of power
5) Cold starting may not be easy in extreme cases
6) Fire hazard & damage to metal surfaces as mentioned above
7) Makes a real mess up the side of the engine!
8) Strange "popping" sound that makes little boys giggle :crazy:
9) Engine runs hot

As I said, these are the effects that I get with a bike when I've thrown the exhaust sytem together badly, but I'd expect them to apply to a car in the same way (but with 8 cylinders rubber mounted, some effects probably won't be noticeable). It's best to fix the leak ASAP as the longer it's left then the harder it will be to get a good seal.