- Feb 18, 2012
- 15
im in the process of replacing my cracked exhaust manifold and wanted to replace the bolts also. does anyone know what grade these bolts are? i was just gonna get new bolts from my parts house instead of the GM ones
BeenBlazin said:i doubt it. its an 04 trailblazer. i already have the manifold. a few of the bolts were broken so im deffinately gonna replace all of them.
BeenBlazin said:doing the exhaust manifold swap isnt hard. the hard part is that usually a few of the bolts break off and have to be removed. then it turns into a real pain. some people drill the bolts and use an easy out. i started welding nuts to the broken bolts to back them out but ran out of welding gas. i already knew the tank was almost empty. when you remove the bolts you want to back them out about 1/4 turn then back in 1/8 then out another 1/4 turn and back in 1/8 and so on. its the high temp thread lock on the bolts that causes the problem.
BeenBlazin said:ya it is a deffinate pain in the ass just be prepared iv heard of a few situations where the bill got pretty high depending on how many bolts break. GM removes the cylinder head and charges i think over a couple of grand. what ever shop you bring it to make sure you discuss the chances of broken bolts and price beforehand so you dont get a big suprise. if you remove the heat shield from the exhaust manifold you can usually see where its cracked. theres lots of cases where people get some high temp furnace cement to patch the crack and theyve had success. in my case the crack ran down the outside and back up the inside so the manifold was pretty much cracked in half. im not trying to scare you just giving you a heads up. some people get it off without breaking any bolts at all. i have 3 broken bolts
Sparky said:I'll probably have to deal with this issue at some point. Last I checked mine wasn't cracked, but I do think I have a busted off bolt already because it sounds like it may have a manifold leak at cold startup in the morning.
How much work is it to pull the head and just have the shop extract the bolts from the head only? I can't imagine it would be fun, but maybe for someone who is more mechanically inclined (or just simply crazy) that might be a cheaper option.
Sparky said:Hmm maybe I should check that. I just figured with all the bolts that are seized and break that there would be no way for them to just simply be loose.
MichEnvoyGuy said:Well, I was very much like you a few years ago and was over on the os searching high and low for how-to on the exh. manifold replacement because after all of the problems I read, I was sure I had a cracked manifold or sheared off bolts in the head. A few other members said their bolts were just loose. I took of my heat shield, fully inspected the manifold and to my surprise there werent any cracks at all! Looked at the bolts, check, they are all there. I could see black carbon at the front of the manifold/head. I put a socket on the bolt and it was so loose I could've turned it a few times and taken it out by hand!![]()
I tightened 3 or 4 bolts that were as loose. The sound difference is amazing. No more cold start up exhaust leak sound coming from the engine. Heck, it even sounded different at cruising speeds, a lot quieter. Check your bolts first, for sure![]()
coleman said:Yeah, I had to use a swivel and an extension. The bolt is definitely in there. I could feel it with my finger and could tell that it was rusty. Must have been that way for quite some time. Hopefully the one I hit did the trick.
MichEnvoyGuy said:Just curious, how tight did you crank the bolts?
I was afraid of breaking them so I snugged them up real good but not gorilla tight. My logic says that I'd rather re-tighten them in a year vs. have to take everything apart (and risk more broken bolts) when I break one by over tightening it.
BeenBlazin said:yes its a led donut. theres 3 studs and nuts that hold your down pipe to the exhaust manifold. are you just smelling exhaust? there could be a leak from several places. are your pipes rusted out? how about your catalytic converter?