Exhuast Manifold Donut Gaskets.

Year, make and model?

Doc

93 Silverado k1500

where you buying them ?

I use Walker from my local Parts Plus

I'd try buying them from another source, maybe even the dealership if you haven't had any luck with the last two. They last damn near forever............

Doc

nope, it's just in an extreme environment that you're asking the gasket to seal in.

-Bret

These gaskets are generally made out of a combination of materials like graphite, metal mesh, and/or asbestos like material that is highly compressed. If you are wearing these out abnormally fast you may want to check for excessive movement of the Y-pipe. These gaskets usually last the life of the vehicle if the Y-pipe is properly secured to prevent flexing under engine torque.

Rita

Rita;

Not to be arguementative, but isn't this gasket in a position, and made to a countour, to ALLOW movement between the manifold and Y-pipe ?

The main reasons i've seen for them wearing out are:

1) el cheapo's 2) deformed end on Y-pipe, allowing a small leak that becomes worse 3) using only bolts instead of a bolt-spring combo G

Gary, I know your not being argumentative, but you may have missed the section of my response that said "excessive movement". I never mentioned NO movement at all. This is the crux of the problem that he most likely is experiencing. While I agree with you that the gaskets were designed to ALLOW movement, any material will wear out if it is in a position of constant EXCESSIVE movement.

This is why GM uses three spring loaded bolts to connect the Y-pipe flange to the manifold. You will notice that GM also uses a bracket that is mounted to the transmission/engine to hold the other end of the Y-pipe as STATIONARY as possible. I'm sure you have worked on vehicles that have this bracket removed? If this bracket is removed EXCESSIVE movement will be transmitted to the Y-pipe under engine torque.

Agreed to a point, but not a problem if PROPERLY installed.

MINOR deformations are what these gaskets were designed to handle. The deformed area will place more pressure in that area and the graphite in the gasket will wear producing a good seal.

I can see this as being a problem that will accelerate wear of the gaskets.

Rita

OK gotcha

but................, then we get to 'how much is excessive?'

my experience is that if the exhaust is supported near the catalytic converter, plus at least two other points rearward from there, it CAN'T move very much

but I've seen 'em with the exhaust pipe held up by the flange to the E.M., and one hanger near the axle, and it just kinda swings in the breeze............

Now you're trying to be argumentative by trying to split hairs.

Yes, I've seen them supported prior to the catalytic converter as you say. And every mounting point afterwards is mounted to the body, usually with hangers that have rubber strapping or bushings. Since these allow SOME movement they work in conjunction with the Y-pipe support.

I have seen the same scenario myself; this doesn't mean that it is correct. EXCESSIVE wear may not be an issue if the exhaust system allows enough movement by not being rigidly mounted to the body. I would put my money on the odds that the vehicle with the Y-pipe support prevents donut wear from improperly mounted exhaust systems.

Rita

no, I'm just saying that what one person considers to be OK, another will consider to be excessive

the guy complaining about the gaskets wearing out might think his is 'OK', when you or I will know it is not

stop trying to read something into a statement that isn't there, OK ?

I didn't say it was 'correct', just that it is something I've seen, and usually the owmer thinks its just peachy-keen..........I left the 'what a crappy installation' part to your imagination

There is no room for "what one person considers to be OK", it's a matter of what IS and what ISN'T. In this case, I will put my money on EXCESIVE movement as defined by the manufacturer.

Again, it doesn't matter what he, you, or myself think. It all boils down to the fact that something is out of its design parameters. Again, I'll put my money on EXCESSIVE movement whether caused by an improperly mounted exhaust system first. If the exhaust system is confirmed to be properly installed I then would consider verifying that the tensioning springs are not damaged. Yes, these springs do wear out at various rates due to heat. This was a problem with older Big Blocks. Weakened springs with high back pressure caused EXCESSIVE movement in that area causing doughnut failure.

I never did. You are the one trying futilely to grasp at a straw that is definitely out of your reach, not me.

Alluding to is just the same as saying so when one is trying to split hairs.

Rita

Gotta chime in my $0.02 here...............

DEFINE EXCESSIVE in measurable terms. 1/4", 1/2", 2"? Where is this "movement" measured, and what is it measured in relation to?

"Knowing" something is one thing, have a concrete measurement to judge if something is shot or not is another. I never "think" rod bearings are "ok" until I spec them out......................

You're still dancing around here, define excessive in a measurable unit!

How long is that straw, does it sway in the wind, and if so, is this swaying "excessive" or within the specs of the straw?

Doc

Doc, I had more respect from you than that. I'm sure you know exactly what I'm talking about so don't play the imbecile. Let me quote you from a few post back in this thread, "They last damn near forever............" You did say this? Right? If you did, then please explain to me what would cause unnaturally high premature wear if "They last damn near forever............" And please don't make the baseless claim that they are "cheap".

Agreed, but we're not talking rocket science here. If, the original poster, Gary, you, or myself don't know the proper specifications or if the exhaust system is properly installed then we need to consult the manual. I don't think this concept is out of the realm of any one of us.

Nope, I gave an answer of what my experience is on this subject. You, or anyone else may chose to use it or not isn't going to hurt my feelings. If you need absolutes in your answers maybe you need to consult the manual and follow the flow charts to solve your problems. I'll rely on my real world experience.

Doc, again, your ignorance is preceding you. Either your intentions are to stir the pot since you don't want your ego bruised knowing you have to admit I'm right or you have limited technical and shop skills? Which is it?

You seem to be contradicting yourself by stating, "They last damn near forever............" but can offer no alternate explanation of premature failure. Maybe, I should play your game and ask what your definition of "forever" is? Since you like to have "concrete measurements" you shouldn't have any problems telling me what "forever" means in finite numerical terms? Also, in your would, does "your" definition of forever stay the same between vehicles you supposedly work on or is this a term you just pulled from your ass? Maybe it's a straw you're pulling from your ass since your not reaching any of the other ones your grasping at.

Rita

measurements"

Rita,

It is fairly obvious from your reply to my post that one of us is completely and utterly lacking a sense of tongue-in-cheek humor. I'll let you guess which one of us it is.

Doc

I admittedly missed the humor. Maybe it was the comedian's delivery of the punch line, or lack of, that failed to derive the desired results? Anyways, I'll leave the donuts to the experts out here and the cops since they need them more than me. It's been nice chatting with you.

Rita

Jeez, Rita, lighten up

First you get all out-of-joint cause I fail to point out that part of what I wrote was a jab at idiot owners who think a two-point attachment of their exhaust is just dandy, now you're on Doc's case cause he tried to inject a bit of humor into this.

You've always been pretty down-to-earth and helpful..............step back, take a deep breath, count to ten, whatever...........you're coming across as.........well, hell, I'm not going to put a label on it, just try to see that all three of us know what's right and what's not, and Doc and I take the occasional jab at the idjuts who are always trying to get by on the cheap, or hay wire things.

OK ?

G

I'm hoping to install some headers in my Jimmy over the next month or so, and naturally they're missing the header/y-pipe bolts. So I should be sticking springs in there too, between each bolt head and the flange? I hadn't thought about it but it does make sense... Dammit, something else to buy.

(Just trying to be a bit more technical than Rita's nonsensical ramblings...)