Muffler Question

[ram1220]

1990 GMC Sierra 5.7l TBI with 156,000 miles. I need a new muffler. The pipes are still good. I went by Midas only because they are really close to my home. Guy said that because the original pipes are welded to the muffler I can not just replace the muffler. He said I have to replace pipe from the cat to muffler as well as both pipes from muffler back. Does this sound right?
I did check out mufflers at Rock Auto. Their info on the mufflers does state that all required parts need to be replaced. But they do not state what those required parts are.
Is it possible to just replace the muffler? Any idea what the required parts would be that Rock Auto is stating on their website? Thanks.

 

[99'Subourbon]

Yeah, you can just replace the muffler. Thing with stock pipes is that they are usually thicker than the typical 16ga piping of exhaust systems. So the OD of the pipe doesn't fit nice and snug inside the ID of the new muffler. Typically you'll just need to but up the end, and well it together that way, or you a exhaust sleeve band; or force it in.

You won't find part #s for this, just measure the diameter of your piping, and buy a matching muffler.

 

[kennythewelder]

Yes it is possible to replace just the muffler. Midas may have a policy that does not allow them to just change the muffler on your truck, I don't know. A large shop like that, may have a reason why they won't just change the muffler. You have to remember that they have to warranty there work.

 

[twomanymontes]

Find yourself a small independent Muffler shop. They will be able to cut the muffler out and weld in a new one. And they are usually cheaper than Midas

 

[ram1220]

Thanks guys. I will find a local small muffler shop and have just the muffler changed. I wish this was something I could do myself. I usually do all the repairs on my truck. But I'm not sure how easy it would be to cut out the old muffler. And I don't know how to weld nor do I have any welding equipment.

 

[jkeaton]

Thanks guys. I will find a local small muffler shop and have just the muffler changed. I wish this was something I could do myself. I usually do all the repairs on my truck. But I'm not sure how easy it would be to cut out the old muffler. And I don't know how to weld nor do I have any welding equipment.

All you need is a sawzall or a metal cutting hand saw (will take a bit longer). I did mine without even having to jack up the truck. Its real simple. Cut the old one just after where the muffler is welded on. Measure the diameter, go buy a cheap aftermarket muffler (you can get a thrush or similar from a local auto parts store for like $30) If you have trouble matching or getting the correct length and/or diameter inlet/outlet size, auto parts stores sell plenty of adapters to match just about any pipe size. Buy some muffler clamps of the correct diameter and clamp the new muffler in. You technically don't have to weld it on. The inlet of the muffler should slide over the intermediate pipe (between the cat and muffler) and the outlet should fit into the tailpipe section. If you do want to weld it, take it to a shop after you get it installed and have them weld the joints. I've done this on countless vehicles.

 

[ram1220]

Thank you. I will probably do it myself.

 

[kennythewelder]

FYI, Keep this in mind when buying a new muffler. most mufflers are restrictive. If you want to gain performance, a muffler that you can look through will be a lot less restrictive than one that you can not see through. If you just want sound, then it doesn't matter so much. Flow Masters are restrictive but sound good. Magnaflows are not restrictive because you can see through them. Even old school glass pack mufflers are not restrictive, and they are cheep. A straight pipe will be the least restrictive, but it is loud.

 

[ram1220]

FYI, Keep this in mind when buying a new muffler. most mufflers are restrictive. If you want to gain performance, a muffler that you can look through will be a lot less restrictive than one that you can not see through. If you just want sound, then it doesn't matter so much. Flow Masters are restrictive but sound good. Magnaflows are not restrictive because you can see through them. Even old school glass pack mufflers are not restrictive, and they are cheep. A straight pipe will be the least restrictive, but it is loud.

Thanks. I just want to keep things stock. Like the truck came from the factory.

 

[kennythewelder]

Y W just want to pass along what I have learned. It is an easy job to replace it your self as mentioned in this thread.