3.1 Crossover Pipe - 1997 Lumina

1997 Lumina. 165k miles. This pipe goes from front bank exh manifold to rear bank exh manifold. Covered by a heat shield, so you can't see it.
I didn't hear it, but my son did.
He also felt the puffing with his fingers on a cold start. He's good. He was concerned about his mom driving it while exhaust gasses could be sucked into the ventilation.
I asked about a new pipe at O'reillys. No go. One of the guys said they used to sell them, but not anymore. Suggested I have a muffler shop make one up.
I called GM, and they wanted $274 for the 18" long pipe. Called the Meineke I use for muffler work and he said bring it in for an estimate. I wanted to save my son a trip to the boneyard and the work if it wasn't more than a $200 job. The Meineke guy took about 1/2 hour checking it out. I wasn't in the shop but looking in a window I saw him sticking a gas probe in there, so I suspect he couldn't hear it either.
When he came out he told me he'd come up with an estimate. I asked what he'b been doing the last half hour and he said he'd have to price the parts, and he'd call me. We talked a bit and I told him what GM wanted for the part, and what the auto store guy said about making it up, and that my son could do it if the price was too high. He said he couldn't make it up because it was stainless steel. The auto parts guy didn't know what he was talking about. We talked a bit about all the crap that had to be moved to get at the pipe, and what could go wrong, and left it at that. He called the next day and said "Vic, you should let your son do it."
Took my son about 2 hours to get the pipe out. Removed airbox, upper rad hose, coolant pipe that runs around the front valve cover, EGR solenoid. Lost about a pint of coolant. One of the 4 small heat shield bolts snapped off, the others came out. Still couldn't get heat shield off. A coolant tube for the heater was in the way. That's stuck in the manifold with an o-ring and special plastic internal clip. Besides that, a brace on the tube is bolted to the manifold in an almost impossible location. I couldn't see it even when he told me where it was. Somehow he managed to get that bolt out - that was half an hour there. I think it may have been easier if we removed the throttle body and/or the entire EGR, but he didn't want to do that. Good enough for me. After that the heat shield came out with some manipulation.
Each end of the crossover pipe is flared. No doughnuts. Loose triangular flanges are put on the pipe before it's flared, and 3 manifold studs go through each flange. Nuts draw the flare down on the manifold external "nipple." No gasketing at all. We heated one nut with Mapp, the others broke loose. No significant rust, and they came off clean. Tapped the pipe with a hammer to free it from the flares.
It's corrugated for about 3 inches about a third of the way from the back. For expansion/contraction. The last rib of the corrugation was cracked open half way around.
The next day he went to the boneyard and extracted a pipe. Said it took him about 10 minutes to get it out. I didn't ask for details. There were 5 Luminas and a Monte Carlo there. He took the pipe from the one with the lowest mileage, 160k. Monte Carlo. 6 bucks.
Took us about an hour to put it all together again. But he's done a lot of work on 3.1's. The worst part with these 3.1's is the coolant tubes. You have to know how to release the clips, and you should put some silicone grease on the o-ring before you push them back in. Clips are cheap if you break one, and you might want to have a new one handy. So now you know what you're up against.
--Vic
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"Vic Smith" wrote in message
1997 Lumina. 165k miles. This pipe goes from front bank exh manifold to rear bank exh manifold. Covered by a heat shield, so you can't see it.
I didn't hear it, but my son did. He also felt the puffing with his fingers on a cold start. He's good. He was concerned about his mom driving it while exhaust gasses could be sucked into the ventilation.
I asked about a new pipe at O'reillys. No go. One of the guys said they used to sell them, but not anymore. Suggested I have a muffler shop make one up.
I called GM, and they wanted $274 for the 18" long pipe. Called the Meineke I use for muffler work and he said bring it in for an estimate. I wanted to save my son a trip to the boneyard and the work if it wasn't more than a $200 job. The Meineke guy took about 1/2 hour checking it out. I wasn't in the shop but looking in a window I saw him sticking a gas probe in there, so I suspect he couldn't hear it either.
When he came out he told me he'd come up with an estimate. I asked what he'b been doing the last half hour and he said he'd have to price the parts, and he'd call me. We talked a bit and I told him what GM wanted for the part, and what the auto store guy said about making it up, and that my son could do it if the price was too high. He said he couldn't make it up because it was stainless steel. The auto parts guy didn't know what he was talking about. We talked a bit about all the crap that had to be moved to get at the pipe, and what could go wrong, and left it at that. He called the next day and said "Vic, you should let your son do it."
Took my son about 2 hours to get the pipe out. Removed airbox, upper rad hose, coolant pipe that runs around the front valve cover, EGR solenoid. Lost about a pint of coolant. One of the 4 small heat shield bolts snapped off, the others came out. Still couldn't get heat shield off. A coolant tube for the heater was in the way. That's stuck in the manifold with an o-ring and special plastic internal clip. Besides that, a brace on the tube is bolted to the manifold in an almost impossible location. I couldn't see it even when he told me where it was. Somehow he managed to get that bolt out - that was half an hour there. I think it may have been easier if we removed the throttle body and/or the entire EGR, but he didn't want to do that. Good enough for me. After that the heat shield came out with some manipulation.
Each end of the crossover pipe is flared. No doughnuts. Loose triangular flanges are put on the pipe before it's flared, and 3 manifold studs go through each flange. Nuts draw the flare down on the manifold external "nipple." No gasketing at all. We heated one nut with Mapp, the others broke loose. No significant rust, and they came off clean. Tapped the pipe with a hammer to free it from the flares.
It's corrugated for about 3 inches about a third of the way from the back. For expansion/contraction. The last rib of the corrugation was cracked open half way around.
The next day he went to the boneyard and extracted a pipe. Said it took him about 10 minutes to get it out. I didn't ask for details. There were 5 Luminas and a Monte Carlo there. He took the pipe from the one with the lowest mileage, 160k. Monte Carlo. 6 bucks.
Took us about an hour to put it all together again. But he's done a lot of work on 3.1's. The worst part with these 3.1's is the coolant tubes. You have to know how to release the clips, and you should put some silicone grease on the o-ring before you push them back in. Clips are cheap if you break one, and you might want to have a new one handy. So now you know what you're up against.
--Vic
Great post, Vic. And thanks for taking the time. Reminds me of the oil pump drive flange leak on my son's 92 Olds Cutlass with a 3.4 Liter DOHC V6. Had to remove the rear head, and suffer the unbelievably sorry method GM has to retime the cams on that engine.
Garrett Fulton
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On Thu, 17 Nov 2011 04:01:29 +0100, "Garrett Fulton"

Thanks, Garret. When I do something "unusual" I try to post about it. Googling a fix procedure has been good to me, so it's payback. Never worked on DOHC, and probably won't. Bad enough getting a pushrod cam/chain/distrubutor all set. For me something you recheck 5 times before you move on.
But it's all the little cooling tube BS on 3.1's and 3800's that torques me and my son. Special fittings and o-rings. He's had broken tubes on both of his. The 3800 even has 2 attached to the belt tensioner assembly to get coolant from one side to the other. His leaked. We both always say, "What's wrong with nipples and rubber hoses?"
--Vic
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"Vic Smith" wrote in message wrote:

Thanks, Garret. When I do something "unusual" I try to post about it. Googling a fix procedure has been good to me, so it's payback. Never worked on DOHC, and probably won't. Bad enough getting a pushrod cam/chain/distrubutor all set. For me something you recheck 5 times before you move on.
But it's all the little cooling tube BS on 3.1's and 3800's that torques me and my son. Special fittings and o-rings. He's had broken tubes on both of his. The 3800 even has 2 attached to the belt tensioner assembly to get coolant from one side to the other. His leaked. We both always say, "What's wrong with nipples and rubber hoses?"
--Vic
Yeah, I googled the fix on that 3.4 L DOHC too. Went to the IATN forum where all the dealer shop mechanics post. Got about 14 replies, going from "raise the oil pump adaptor flange high enough to slide in an o-ring that you have slit diagonally" to "take a hacksaw and cut enough off the corner of the cyl. head to pull out the pump drive". And two guys that wrote,"only way to do it right is remove the head". I voted for the latter. But, man, what a job. Hope none of my cars ever end up in the care of hacksaw man. Ha.
Garrett
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