Untitled Document

Crossover Pipe

Last Updated: June 23, 2000

Applies to:

1989-90 Pontiac Grand Prix Turbo
1990 Pontiac Grand Prix STE Turbo

Symptoms
The symptoms of a cracked crossover pipe include (but are not limited to): stalling, poor fuel economy, exhaust fumes, low peak boost, weak spot at wide open throttle at about 4,500 rpms, failed oxygen sensors, failed catalytic converters, failed government emissions testing, and others. Even if your car does not exibit obvious symptoms, your crossover pipe is cracked if it is the original (or a replacement) GM Pipe. There is no doubt about it. A GM crossover pipe will have these cracks!

The Cause
The crossover pipe cracks at the flexible bellows. There are two flexible bellows on the crossover pipe; each of the bellows is between the exhaust manifold and the outlet to the turbo. Here are some pictures illustrating the cracks:

	This picture shows the crossover pipe after I pulled it out of my TGP. The problem bellows are hidden from view due to the outer heat shield of the crossover pipe. The bellows are inside the two bulged areas on the heat shield.
	The heat shield is just 2 pieces of stamped spot welded together. To remove the shield required drilling out the spot welds. The picture on the left shows a freshly opened crossover, revealing the naked crossover pipe inside.
	This is what the crossover looks like with the heat shield completely removed. Notice how the insulation material (white asbestos) is stained black with carbon due to the cracks in the bellows!
	Here is a naked and cleaned crossover pipe. You can clearly see the flexible bellows in this picture. Can you see where they are cracked?
	Zooming in to the bellows on the longer side, the crack is now obvious!
	What's this? A crack on the other bellows too! This is the bellows on the shorter side. Man, these bellows really stink!

Isolated case? No way. ALL GM crossover pipes on the TGP will crack. I had been hearing about cracked TGP crossovers for months before I even bought my own TGP. When I got my TGP with just 81,266 miles on it, sure enough, my crossover was cracked too. In fact, the pictures above were from my car. See below for a picture of a crossover from a different TGP!

Picture of an old crossover pipe with 3 cracks in the flexible bellows. Picture courtesy Jeff Middaugh.

Solutions
You'll have to drop nearly a grand to purchase a brand new crossover pipe, GM p/n 12397801. Its lowest street price is currently $986.06 shipped (GM Parts Direct, 1/24/03)!!! Unfortunately, GM never redesigned the crossover pipe, so at this price, it's not exactly a desirable solution. The turbo 3.1L was also rare enough that they will be hard to find at salvage yards, and any crossover pipe in a salvage yard is going to be cracked in the bellows anyway. You don't have to live with a cracked crossover pipe though. There are a few solutions:

Cheap and Dirty - Well, there is not really any cheap and dirty way to fix it. You could try fudging it with JBWeld or some other exhaust patching substance, but you're not going to get very permanent results. In fact, I wouldn't expect it would last one trip. Not really worth the effort to remove the heat shield just to fudge it.
Budget Fix - Replace the bellows with straight pipe. This will cost probably about $140 if you have an exhaust shop do the work. This might work, but could end up being a short term solution as the heat and stress of the exhaust can cause the welds to crack over time. Solid pipe may also cause a poor fit at the end fittings that attach to the manifolds - perhaps not when the engine is cold, but through the entire range of operating temperatures, the fitment can change. The lack of flex joints may also cause additional stress on manifolds and cylinder heads as the pipe expands under temperature. The crossover is also made of T-409 stainless steel, but most exhaust shops deal primarily only with aluminized mild steel, and as a result, the pipe will be more prone to corrosion problems.

This is a picture of a crossover pipe that was repaired the cheap way by an exhaust shop.
Better Fix - Replace the bellows with braided flex couplings. This will cost about $200-250 at an exhaust shop. Problems with this method may include the exhaust shop not getting a perfect fit, the flex joints may corrode due to not being made of stainless steel, etc. If you are skilled at TIG welding, you might be able to fix it yourself, but premium quality T-409 flex joints are difficult to find.
Best Fix - Purchase a remanufactured pipe by Jeff Middaugh (a189pgt at earthlink dot net). These pipes are currently the best because they are constructed with a premium flex joint/bellows. The pipe ends are also dressed and re-formed to ensure they mate with the exhaust manifolds. These pipes cost $425 (w/exchange) and are worth it for the quality construction and peace of mind that this is the last time you will have to be worrying about the crossover pipe. For more information about Jeff's pipes (and some comparison pictures), click here.