I just bought a pampered, one-owner '96 LSS (n/a) with 82,000 miles that was traded into the dealership where it was bought new. I checked the UIM and it has an '06 date code on it, so it looks like it was replaced very recently. My question is, how concerned should I be about the LIM gasket and EGR degradation of the UIM? Does anyone know what the dealerships typically do when they replace the UIM? It'* still running the orange coolant, too.
Thanks,
Jim

if it was purchased, serviced, and traded all at the same dealer, they should have a record of exactly what was done.

Ask the dealer if they will give you the name of the previous owner and try to find out exactly what was done. Without that information, to be safe, you must assume that the LIM gaskets have not been changed. Even if they were, chances are slim you have the good aluminum frame gaskets. If the new UIM and your old LIM are GM stock, then the stovepipe is right up against the plastic. If it were mine, I would pull the throttle body and have a look-see. For a long time, GM dealers replaced the entire LIM with the newer version just to get a smaller diameter EGR stovepipe. The EGR pipe sits right behind the throttle body - you will be able to tell pretty easily if you have the newer 5/8" GM stovepipe (better) or the old 3/4" stovepipe right up against the plastic UIM (not good).

Your best fix is to have a metal heat shield in the UIM, a reduced diameter stovepipe, aluminum LIM gaskets and NO Dex. You are looking at about $250 to get all of the parts you need off the shelf to do it up right.

I'll talk to the salesman to see if he can get a copy of the service record. $250 for gaskets, EGR tube & coolant? Didn't think it would cost that much. Are the gaskets pretty expensive?
Thanks,
Jim

As I recall, mine were about $60 from GMPartsdirect.com.

They're 50-something at INTENSE.

To clarify, here'* where I estimated $250

New, APN upper intake manifold (UIM gasket, stovepipes included) $115
GM aluminum frame lower intake manifold gaskets $70
Dorman coolant elbow(*) $5
Five quarts of oil and filter $15
Two gallons of "mixes with any color" coolant $16
One can of brake cleaner $4
Rags, nitrile gloves $5
Thermostat and two gaskets $10

This assumes you buy your parts "ready to use," and that you have about a 6% state sales tax. Also included above is the cost of shipping. You can sleeve, or plug your own UIM, for less money, but when you consider that you get gaskets with the kit, the money you pay for the new UIM is somewhere around $60-$70. That is an unbeatable price for a new, sleeved UIM. If you want to do the work and your UIM is in good shape, then you could save $45-50. For most folks, the economics favor the APN kit.

Also, the LIM gaskets vary in price from dealer to dealer. I think maybe Intense sells them too. (Edit: thanks, willwren for the Intense confirm)

You most likely have just the reduced EGR tube with that replacement UIM. They were using that as early as 2000. Dealer would not routinely replace the LIM gasket when they did the UIM. Ditto checking with dealer records and previous owner. Failing that, look closely where LIM meets heads and block and see if there are any deposits at those seams. If the gaskets were replaced just a year ago it should look pretty clean there. Good luck with a nice car.