Exhaust Pipe to Manifold Gasket

[wormwood1978]

What is going on here?

My 08 TB 4.2 has 115k on it. Cracked manifold at 75K which fixed the diesel sound. Increasing loud exhaust again at 92k, fix was replacing the exhaust pipe to manifold gasket/donut. Shop used NAPA part 31657 which appears to be a Walker part. Same problem again at 99k, same fix with part 31657. Now at 115k, same problem same fix. What is going on here?

I'm thinking about doing the work myself next time and going with the OEM AC Delco 15167765 part. I do all of my own maintenance and some of my own repairs unless it looks like too much of pain or the middle of winter. This looks like it can be a bit of pain because of where the gasket is and getting to the bolts.

Additional caveat, complaint. For the latest fix, I originally took it to a different shop as they could get me in the next day where my usual shop was booking three weeks out. I told this shop what I thought the problem was because it had been twice repaired before and I had sprayed soaping water on the area and it was clearly leaking. I paid their 1/2 hour diagnostic fee to have them tell me they didn't that the exhaust pipe gasket was the problem rather they thought it was a cracked manifold again and wanted $1,000 for the repair. I said no thanks to them and won't go back there. I then waited for my regular shop to get me in who said it was the gasket, replaced and now back to being quiet.

 

[6716]

I have had similar issues recently with noise from the gasket. I replaced the cat section myself 25k miles ago but didn't replace the gasket even though it would have been the right thing. Had a lot of running noise, thought it was a cracked manifold, seems like it was the bolts letting loose at the cat to manifold junction. Brought it to a shop since I don't have garage space myself right now, they tightened it up and said it might be the gasket. Had noise not too many miles later, brought it back, they said, let's redo the gasket. Don't have enough miles so far to decide if that is a good enough fix.

The pipe to manifold bolts aren't so hard to deal with if you are under the vehicle and have a long enough extension.

Also, it could be the manifold again. I would want to see what they were seeing to say that, but it is not impossible the replacement failed early.

 

[JayArr]

I've had the same problem, I've burned through multiple Walker donuts and this last time I bought an OEM GMC donut and what a world of difference in quality!

The walker donuts are soft, cheap, metal molded onto a mesh and they fail easier. The OEM one is a solid material that appears like it will last a long time.

Here's something to remember. OEM parts are designed to last the length of the original warranty coming off the factory line, that can be anywhere from 5-10 years. The Walker donut has no such quality commitments, they would love to sell you a new one every year.

I had the same experience with rad caps, multiple brand new Napa rad caps would fail the pressure test and would not hold 15lbs but the OEM one solved my overheat problem.

I got the OEM donut from Rock Auto.


EDIT: Note that back pressure from a clogged catylitic converter will cause that donut to fail faster than usual. Is your vehicle sluggish and lacking power?

 

[wormwood1978]

I've had the same problem, I've burned through multiple Walker donuts and this last time I bought an OEM GMC donut and what a world of difference in quality!

The walker donuts are soft, cheap, metal molded onto a mesh and they fail easier. The OEM one is a solid material that appears like it will last a long time.

Here's something to remember. OEM parts are designed to last the length of the original warranty coming off the factory line, that can be anywhere from 5-10 years. The Walker donut has no such quality commitments, they would love to sell you a new one every year.

I had the same experience with rad caps, multiple brand new Napa rad caps would fail the pressure test and would not hold 15lbs but the OEM one solved my overheat problem.

I got the OEM donut from Rock Auto.


EDIT: Note that back pressure from a clogged catylitic converter will cause that donut to fail faster than usual. Is your vehicle sluggish and lacking power?

Yes, next time the gasket fails which I'm guessing will be next year, I'm going with the Rock Auto OEM gasket. How difficult or easy was it to change yourself?

 

[JayArr]

Really easy if you have or buy a long extension. I have a Performance Tool set that has 18", 24" and 30" - incredibly handy. The extension just follows up the side of the pipe from below and takes the nuts off without any trouble at all.

With the 24" extension it's just three nuts, from underneath with the front wheels on ramps. Then I use a ratchet strap to pull the whole exhaust system back a few inches and reach up and install a new one. Shouldn't take more than an hour for the whole job.

Without the extension, trying to undo those three nuts from above or with a wrench or a regular ratchet could take hours.

Hint: There is a union piece on the pipe that the three studs come through. It needs to slide off the studs evenly. If the pipe and manifold line up properly it will slide easily off. If it gets cocked it will not come off. If it won't come off then the pipe and manifold are not lined up correctly and you'll need to wiggle the pipe around. There is no way to force it off, it's a triangle around a circle. I tried to pound it off once and got it off two of the three studs and it jammed and wouldn't come off and wouldn't go back on, I had to cut one stud to free it. Same going on, if the pipe and manifold are lined up it will slide up onto the studs.

 

[wormwood1978]

Really easy if you have or buy a long extension. I have a Performance Tool set that has 18", 24" and 30" - incredibly handy. The extension just follows up the side of the pipe from below and takes the nuts off without any trouble at all.

With the 24" extension it's just three nuts, from underneath with the front wheels on ramps. Then I use a ratchet strap to pull the whole exhaust system back a few inches and reach up and install a new one. Shouldn't take more than an hour for the whole job.

Without the extension, trying to undo those three nuts from above or with a wrench or a regular ratchet could take hours.

Hint: There is a union piece on the pipe that the three studs come through. It needs to slide off the studs evenly. If the pipe and manifold line up properly it will slide easily off. If it gets cocked it will not come off. If it won't come off then the pipe and manifold are not lined up correctly and you'll need to wiggle the pipe around. There is no way to force it off, it's a triangle around a circle. I tried to pound it off once and got it off two of the three studs and it jammed and wouldn't come off and wouldn't go back on, I had to cut one stud to free it. Same going on, if the pipe and manifold are lined up it will slide up onto the studs.

thank you, I will be doing this next year I imagine