Originally Posted by mdrose64
need one of these stove pipes,I am doing the intake befor I install an engine and would like to take all precautions to avoid another wiped out motor. The engine I an removing has a 2004 UIM so as I look at it , it looks like they never did the LIM hence the motor fried.The engine I am putting in is a 1996 GP engine with 78000 miles. So I would guess I want to use the newer UIM if in good condition and the Stove pipe from the engine I am removing becasus it is from an 2001 GP with the smaller od stove pipe? Can How long does the 7/8 in sleeve need to be and does it have a shoulder? I would in a tubing plant so I can get whatever I need ? If not I will buy one... Thanks
Please start by reading the Techinfo article on this common problem: http://www.bonnevilleclub.com/forum/...e=article&k=38
The stovepipe bore in a 95-98 LIM is .750" - the stovepipe bore in 99 and newer LIMs is .625". Assuming the LIMs are stock, the pipes will not swap. You can make an adapter for the smaller pipe to fit the larger bore.
Old UIMs need to be carefully examined for warpage at the throttle body and on the coolant passage / EGR bore sealing surfaces with a straightedge. The EGR bore must be aggressively probed with a sharp instrument like a dental pick, or an upholstery needle held with vise-grips. Probe the outside top surface of the UIM to determine what the plastic should feel like when it is undamaged by exposure to heat. Then probe the interior of the EGR bore, especially near the bottom. If the EGR bore is noticeably softer, you would be wise to buy a new APN upper kit. If the bore is sound and the sealing surfaces are good, you can install a heat shield and a smaller diameter stovepipe to effect a lasting fix.
I have a few prototype shielded stovepipes left and could provide you with one to fit your 95-98 LIM. They are described here: http://www.bonnevilleclub.com/forum/...ic.php?t=70553
If your UIM is in good shape and you want to try one of these, PM me.
If you work in a tubing plant, perhaps you could help us all by obtaining some thin wall (.020") stainless with an outside diameter that will allow it to be press-fit into the EGR bore of a new Dorman UIM. Does your plant have those capabilities? If so, please PM me to discuss.
In the absence of custom-drawn tubing, we have been using .035" wall 304 stainless tubing .875" OD and .805" ID. The height needed to cover the plastic is .820". A shoulder is not easily managed because the base of the EGR passage in the UIM is closely surrounded by a silicone bead seal in the UIM gasket. The plastic EGR bore in the UIM needs to be enlarged carefully so that the coolant passages are not breached and the sleeve installed with regular JB weld. This provides a heat shield in the bore with an ID of .805"
You can make a stovepipe by pressing a ring of heavy wall .750 OD seamless stainless steel tubing onto a smaller 5/8" pipe and driving into your LIM bore. These procedures including sources of supply are described in various threads that are archived here on BC.