Exhaust smell

[machgirl]

I have an exhaust smell that comes into the driver side window when its rolled down...my dad had checked the manifolds to see if they were tight..they are. The only thing he thinks it could be is the gasket where the pipes meet in the middle of the exhaust....does this sound like a possibility? If so, how hard is it to replace the gasket?

[A1Fiddler]

It's possible. They aren't hard to replace though.

[machgirl]

It's possible. They aren't hard to replace though.

What do we have to do to replace it?

[evolutionmovement]

It all depends on how rusty things are. Should just be a gasket, could end up being pipes and hardware, too, if everything's rusty.

[machgirl]

Nothing is rusty, at least from the outside.

[Imprezive]

try running the car and putting your hand near the gasket areas to see if you can feel any exhaust leaks. You might be able to hear the leak as well if its big enough.

Things may not look rusty but can often be seized up, make sure you soak any bolts in WD 40 or equivalent penetrating lubricant for a day or so before trying to crack anything loose.

[evolutionmovement]

PB Blaster is probably the best thing to spray it with outside of marine supply penetrants.

[machgirl]

[machgirl]

Guy at muffler shop said he couldn't find a leak, and the muffler itself has a cover on it, that's what has holes in it. He said the car seem to be running rich....great, so another thing to try and tackle.

[jp233]

don't fret. hell, that looks like a LOT less rust

Those manifold gaskets can blow out chunks due to age, as they crack and fall apart due to the *extreme* temp swings they see, and just a long life on the car. Remember the car is what, 15 years old?

Even if the bolts on the manifolds are tight to the heads, that doesn't mean that the gasket isn't leaking. Can you hear a valve tick that coincides with motor RPM? Normally that means the manifold is leaking somewhere.

The pipe/flange gaskets can go too. Note that the one in your pic is a donut gasket, one that compresses a bunch when it is installed. Those things need to have a good bit of RTV on them to help seal well. And the springs on those bolts need to keep good tension.

I see that big worm clamp you have around the heat shield, was it rattling? If so, that means that rusty rot took out the clamps/mounting hardware which caused it to break. That means it's a possibility that the pipe/cat/etc may have a pinhole that has developed in it, causing the leak. Small leaks are hard to find with all the heat shields on these cars. Normally they will show up on exposed pipe pretty easily with a dark sooty crud that comes out of them, but if it's underneath a heat shield, may be impossible to find.

I have a rattling heat shield on my 94 that is a PITA because it's hard to find exhaust nowadays unless you go custom, and with a 14 yr old N/A car, I'm not that interested to chunk a few hundred bucks into something that is a commuter car and little else. Anyways,

Your best bet is to remove the front exhaust at the donut gasket which is behind the cat (i.e. the one about a foot or two past the cat, which is out in the open rather than the one at the exit of the cat, which has heat shields all around it). If nothing pipe-wise or cat-wise is broken (easy to inspect the thing closely on the floor rather than under the car). if all seems well Replace all the gaskets and be sure to use high-temp RTV like Permatex Ultra-Copper or just the Red stuff. Torque it all up and you should be fine.

I'm going through the same damn thing right now...... new manifold gasket decided to leak after about 100 miles. When I removed the rusty nuts for them, 5 out of 6 studs came right out of the head. I wondered if normal bolts would be fine for this (well, serrated flange bolts with lockwashers), and from an engineering standpoint I can see no difference. Studs are just put in there for ease of assembly and lining up the exhaust. None of the studs that came out had any sort of sealant/loctite on them....

[93forestpearl]

It is fine if the whole stud comes out with the nut. It will provide the same clamping force when you torque it back to spec. I've taken over a dozen exhaust manifolds off where 4 out of the six studs come out with the nut. No leakage problems when I put it back together.



If you do take the manifold off to try to re-seal it, you might want to try turbo gaskets. Turbo gaskets are of a multilayer steel design vs. the sandwich construction, and hold up to much higher temps and abuse. They don't work when you re-use them though, neither do the NA gaskets.

[Buffman]

yeah all of my exhaust manny bolts were tight, but a simple seafoam test revealed the manifolds were leaking. Old gaskets looked like poop