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Exhaust Manifold Removal

J

J7319M

New member
2000 Buick LeSabre w/ 3800 Series II V6.

I have the factory service manual, but it don't say much. As some of you may know, I plan on replacing the rear cylinder head. Just thought maybe you guys might have some tips and warnings about pulling the rear exhaust manifold. One thing I'm not so sure about is whether the exhaust manifold is fastened to the cylinder head with bolts, or if it slides onto threaded studs and is secured with nuts. If it's on studs, then I won't have to worry about breaking a bolt off into the cylinder head. It would be nice if it slid on studs like the A/C compressor. :)
 


two studs on the two outer holes iirc they are 4.5 mm ends of the studs. the rest are normal bolts, you can re use all of the exhaust bolts too. dont trash the gasket, you can re use it.
 
I put the car up on ramps last night and slid under there to take a look. I saw the down pipe you guys are talking about. The nuts for it are easily accessible; however, the exhaust manifold itself looks like it's not going to want to come out the bottom. The transaxle seems to be blocking it pretty good. And I can't roll the engine forward like you guys can with the dog bone mounts because the Buick has lower mounts. There has to be a way though. :D
 
lower rear sub frame, slide it out the bottom.

034_zpsa6865e3d.jpg
 
that is a pic of a rack swap, you want to have a jack stands under the car, a floor jack under the middle rear frame jacked up to it, then back out both rear bolts to their lest few threads, then lower the frame to the bolts, but keep the weight on the jack. with the rack installed you can tear the shaft apart if you go to low. leaving the bolts in is a good guide / drop limit.
 


ive seen vids of them coming out the top in gp's, all you can do is try, if it dont come up you'll have to go out the bottom.
 
I took mine out from the top when I put Plogs on. Just ratchet strap the engine forward and you'll have clearance.

Edit: NM. I see you're in an H-body. I'd still think they could come out the top somehow.
 
its a le sabra, not the same engine mounts, his wont pull forward like ours.

thats a H body aint it? you should have a metric ton of room back there iirc.
 


with the down pipe un bolted. id just un bolt it from the head and lift the head off. cause the cross over bolts will break, maybe the dp bolts strip or break, not worth the aggravation.
 
I was going to dowse the down pipe bolts with Kroil. Same with the exhaust manifold bolts if I can get to them. California car. No salt corrosion.
 
Being a LeSlopper.. aka Bonneville with different body panels. I'm here to tell you that manifold will come right out the bottom w/o a single worry if the downpipe is out of the way. But then..that's kinda your problem. You need to drop the entire exhaust because on the LeSabre, it's all one piece stock except the exhaust tip.

That rear manifold will be super easy to take out if you have a 3 foot extension and a ball pivot snap on deep 13mm and 10mm sockets. The EGR is likely a 10mm (on later model w bodies it was 13mm). The rest of the exhaust bolts will be 13mm and it'll honestly fall right on your head if you aren't paying attention. I pulled the rear header off my bonne in under 10 min (header is longer and odd bends compared to rear manifold). I think you'd probably be at it for about an hour to have that manifold out.

If you are concerned about bolts coming out, run the car up to temp and then pull the bolts. I've never had a bolt going into the head fight, the 15mm ones to the downpipe..that's another story. I've ground the heads off them when necessary. But running the car should help you there too.
 
Here's what you are looking at


Oh..I forgot..there's 4 crusted to hell nuts right in front of the cat. If you can get those 13's off.. you are home free


Here's your rear manifold next to a ported one.


 


It's an H body. H could stand for Huge amounts of room. You don't have to touch the subframe. Unbolt it.. watch your forehead..cause it'll come out pretty darn easy.
 
Bill - is there any chance I can get by with a deep socket and a universal joint, or do I need those deep swivel sockets ? And you mean 3/8 drive, correct ?
 
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