cracked crossover pipe - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 05-08-2005, 12:41 PM   #1
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Default cracked crossover pipe

I have a crack in my crossover pipe that I highly suspect is causing severe KR (up to 20 degrees). I can see the carbon tracking out the split on the heat shield. The plan is to crack open the heat shield and weld her up this weekend on the car (hopefully if the crack position allows). My fear is that I may not be able to get to it, which means I would have to pull the pipe. Advance, GMpartsdirect, and Rock Auto all show only one gasket for the crossover pipe. The front manifold and crossover pipe are listed as two separate parts. Is the front exhaust manifold and the crossover pipe one in the same, welded together, or what? If I have to yank it, how difficult is this gonna be and what friggin gaskets do I need? Anyone have a parts diagram they can scan and email me?
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Old 05-08-2005, 12:48 PM   #2
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My exploded parts diagram (not my FSM) shows that the 93 crossover pipe is serviced with the front manifold. I interpret that to mean they are one piece, or not intended to be seperated. This would mean you only need one gasket.

I can check my FSM'* later if you want. But for the record, a minimal amount of carbon 'scoring' on the heat shield is normal. You may have to remove your throttle body to get it out, but that'* a good opportunity to thoroughly clean it anyway.
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Old 05-08-2005, 01:04 PM   #3
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Thanks Bill.

That would mean if I removed it, one manifold gasket and one crossover to rear manifold gasket, I think. Thanks, for the heads up on the carbon scoring, I doubted it myself and took it to the local exhaust shop who verified it the best they could (they did not remove the heat shield). I can't find cracks anywhere else and the crossover is the easiest place to start considering the scoring. Maybe lady luck will be with me. If you could doublecheck the FSM when you have time I would appreciate it. Are cracks prone to happen anywhere specific?

I hear ya on the TB. Good idea, guess you can;t clean it too many times. I did just buy two other TB'* from a salvage yard dirt cheap (complete with IAC'*). I am thinking of sending one away for porting and polishing (after I get this KR issue resolved). Did you ever install the one that you enhanced? Original MAF work or did you have to alter the MAF or PCM? I am thinking that a P&P TB may not provide much gain unless a super secret project were finished at some point in the new future allowing one to run a smaller pulley. But that might be a mute point if this car is eventually donated to my son and replaced with a S2.
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Old 05-08-2005, 01:12 PM   #4
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I'll check my FSM'* and be back to you later today.

The ported TB would work well with either a super secret project, or a cam. But I now believe other work is necessary. My car is still top-end torn down, but starting to go back together in some respects. I have not run the ported TB, but it was quite easy to do.

I don't anticipate any changes to the PCM or MAF, and you're running the same combination I am. I believe our MAF tables in the JET Stage II are robust enough to support a 15% (calculated) increase in flow.
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Old 05-08-2005, 01:15 PM   #5
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I'm assuming theres a difference between 93 and 95. My crossover is part of the fem. There are no gaskets from manifold to block, only from fem to rem.
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Old 05-08-2005, 01:57 PM   #6
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My book states that 93 and 94 are one piece, and that 95-99 are two seperate pieces, but I'm going on the assumption that the 95 L67 is the same as 93-94 Series 1.

92 was an oddball year, with the 'type 1' being two-piece, and later in the year of production, it switched to the 93/94 (95 Series1 L67) style.

All Series 2 from 95 on are a totally different arrangement, as the FEM and REM switched to cast iron true manifolds, instead of quasi-headers, or tubular manifolds that the Series 1 L67 and L27'* got.
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Old 05-08-2005, 10:17 PM   #7
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Quote:
Originally Posted by willwren
All Series 2 from 95 on are a totally different arrangement, as the FEM and REM switched to cast iron true manifolds, instead of quasi-headers, or tubular manifolds that the Series 1 L67 and L27'* got.
Only the front is cast on the 95+
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Old 05-08-2005, 11:32 PM   #8
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95 series I is still cast even though it'* the quasi situation you explained, right Bill?
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Old 05-08-2005, 11:36 PM   #9
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To the best of my knowledge, you should have tubular welded stainless steel front and rear manifolds like me. But the L36 (SSE, SLE, SE) in 95 should have the cast iron manifold.
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Old 05-20-2005, 01:10 PM   #10
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Boy, this was fun.

Crossover pipe was fine, the carbon tracking on the heat shield was normal, just as you said Bill (all hail the 'Zilla master). Pulled the front Exhaust Manifold off and found cracks radiating out from the weld on the #5 tube. We butchered it with a MIG, enough to get me by for awhile (and cracked the EGR stove pipe too), but now needs to be replaced (a perfect example as to why you should not play with fire unless you know what you are doing).

So here'* the question: EM'* are very pricey from anywhere. I found this in another thread:

http://www.hulkspeed.com/

All of these are 3 piece manifolds, mine is 2. I emailed, but we are unsure if the 3 piece will work on my car. Anybody have a guess? If so, the price is right, the finish looks nice, and I would put them on. If not, this sucks.
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