I am trying to decide on replacing the intake gasket and UIM on a motor I am ready to put in . I know the intake and LI gasket were replaced in 2002 anyway that is the date on the Delphi UIM .. If it is the first design I definitly want to replace the LIM gaskets and then check out the UIM... Everything looks good.. I can see the black silione from the previous intake gasket change...Thanks

I believe the aluminum frame LIM gaskets came out in late 2005. We saw our first set in March of 2006. See this topic: http://www.bonnevilleclub.com/forum/...ic.php?t=49911 If yours were replaced before then, you probably still have the plastic ones. And if if those LIM gaskets saw Dex cool for five years, it would be prudent to replace them with the aluminum frame gaskets from the GM dealer. Add a heat shield for the EGR bore in the UIM and a reduced diameter stovepipe, and internal coolant leaks should have no place in your future.

Now, re different designs for the LIM gaskets. The older block side rails (1995-mid 1997) were straight with no holes. After 97, the side or end-rails of the engine block were cast with holes for pins in the gaskets to better keep the gasket pieces in place. The newer gasket sets with pins on the side pieces will fit on the old rails; the locating pins just kinda hang out in space over the end of the LIM. Doesn't hurt a thing. jr's3800 likes to run a bead of rtv on the rails to keep the gasket side pieces in place and to discourage seeps. I like to put them in dry with just a dab of rtv in the corners, but mine do seep a bit after a couple of years.


[Edited to correct year change for pins on end rails to mid 1997]

The input and guidance/suggetions, has been considerable and appreciated.

Yesterday, I dropped into a local GM dealership, to see if they could 'bring up' on their computer any work which was done on my car ---- relative the replacing of my UIM. As I'm having the initial phase of the EGR Stovepipe coolant leakate, I noticed that the UIM has a stamped manufacturing date of 5.23.03. The service writer said that due to the age of the car, the system will not have it in there. Any comments guys ???

I'll be ordering the parts, but will have to find someone in the West Los Angeles area/Santa Monica area to actually do the work.

This site has been an unbelievable learning forum. The articulate, detailed, with supporting assistive pictures, has simply been impressive to say the least.

At this point I believe the best info you'll need is already above in Billbuttermore'* post.

The service info on your car, while nice to know, is probably moot at this point if you have symptoms of UIM failure. Like said and as you know, just go ahead and get the new aluminum-framed LIM gaskets and an APN or Gorman UIM and have someone local put them in for you.

I say that only because you already stated that you will not be doing the actual work yourself. It'* still important to know exactly which parts will be going back in there, as many service shops are not aware of the new and improved replacement parts available for these fixes.

Thank you Lash...

Thanks for the kind words, Luke.

Make sure your prospective mechanic knows that you will be supplying the aluminum frame gaskets, the UIM and a new stovepipe when you approach him about estimating the cost of the job. It would probably work out best if you had the parts in hand to show the mechanic so they can see the quality of the parts you are providing. Some mechanics may be reasonably reluctant to let a customer choose the parts they have to work with, especially when customers expect a reasonable guarantee for the work provided. If the mechanic can see what he will be working with, he will be much more likely to agree to do the job for you.

Many shops factor in a profit on the parts they provide, and can thereby offer you a lower labor rate when they charge you retail for parts they obtain at wholesale. If you supply a majority of the parts, they will need to know that up front in order to calculate a fair profit for the job. If their labor rates are up on the wall, they may hesitate to perform the work because they cannot maintain their profit margin without increasing the published hours or cost of labor.

My recommendations for UIM/LIM repairs for the 95-05 L36:

Please note that if you cannot wait for parts in the mail, you will not get the best fix.

The best fix for the LIM - GM aluminum frame gaskets......$59
The best fix for the coolant elbow(*) Dorman Help.........$6
The best fix for the UIM - APN upper intake manifold kit......$115 including shipping

In addition, I recommend the following steps to keep engine operating temperatures down, to ensure that coolant flows around the hot stovepipe area in the plastic UIM, and to eliminate any possible harm from the use of Dex-cool - all factors that protect and extend the life of the UIM and LIM gaskets.

Flush coolant and re-fill with "mixes with any color"
Drill a 1/16" hole in a 180F thermostat flange and refill according to: http://www.bonnevilleclub.com/forum/...=article&k=100
Install an after-market transmission cooler.

I use only a scraper and degreaser to clean gasket surfaces on the cylinder heads to avoid introducing abrasives into the engine. I use blue loctite on the LIM and UIM bolts.
I remove the exhaust crossover for better access to the throttle body bolts and easier removal of the LIM.

Regarding the UIM, the longest-lasting fix will come from an upper intake manifold protected by a heat shield and the use of a reduced diameter stovepipe to provide an insulating gap between the hot stovepipe and the metal heat shield. The only commercially available kit that provides those features is from APN. Dorman UIMs have NO heat shield protection for the plastic EGR bore, but rely solely on the insulating gap provided by a reduced diameter stovepipe.

UIMs can be sleeved, plugged, and otherwise repaired for re-use, and these repairs can be made at low cost. But, unless the UIM is fairly new, most will typically exhibit warpage at the throttle body sealing surface and at the coolant passage sealing surfaces around the EGR bore. When considering repair of a UIM, don't forget to add the costs of a new UIM-LIM gasket and throttle body gasket, typically about $45.

From Sears, a smaller 3/8" drive deflecting beam type torque wrench does just fine for UIM/LIM work. It costs $25. http://www.sears.com/sr/javasr/produ...id=00944690000

I agree with Bill on this.

If you are up front with a decent mechanic, you are more likely to get exactly what you pay for and what you think you paid for.

Another option for you is to provide them with a list of the exact part numbers and the stovepipe sleeve, along with some pictures and info from this site, so that they know what your expectations are. You should tell him that your intent is not to "control" his work, but just to make sure he knows about the improved options out there so that you don't have to do this repair again.

He/she may surprise you and know all about it, but then again, maybe not.

I just want to thank you for the info on the gaskets. I pulled the UIM and it looks really good. No decay at all. I pulled at it with a dental pic and it is ok. The lower intake gasket was ready to go though, even though it was replaced in 2002. you could also see where some one at some point added sealer to the system. There was dex cool in this engine. I will flush it all out and replace the UIM and LIM Gaskets and install some type of sleeve in the intake. I do have a coupe qusetions though. How do I get the broken piece of coolant elbow out and reinstall the new one? Also how do I get the piece of stove pipe out of the LIM to install some type of reduce in the LIM? One more thing. Do you put the gaskets on dry of do you install them with some copper RTV?

You might be able to tease the broken coolant elbow out with the right size bolt head slipped inside. You could also try a carriage bolt that will thread into the ID of the plastic. Be careful not to scratch the aluminum bore. The seal is made with an o-ring and if you gouge it, you will have a leak when you install the new one.

What year and trim level is your car? If the UIM is really in good shape - i.e., solid in the EGR passage, little or no warpage on the underside around the EGR bore and coolant passages, and little or no warpage on the throttle body sealing surface, you have several options. You can enlarge the EGR bore and install a .875: OD x .805 ID sleeve in the UIM; you can install a .750" x .710" sleeve by just cleaning the bore and filling the .015" gap around the sleeve with high temperature copper rtv silicone; you can install a shielded stovepipe that will give you a .100" insulating gap and protect the EGR bore without touching the UIM. I have all of these materials but it matters what year your car is.

Stovepipe is removed by slipping a socket or tight fitting bolt in the pipe, then taking a good bite with a pair of vise grips. (The socket prevents you from crushing the pipe.) Spray some PB penetrating oil around the base; tap the top of the pipe. Wait a few minutes then lift as you twist the pipe.

If you want to obtain a sleeve or a reduced diameter stovepipe, and your car is 99 or newer, do NOT remove your stovepipe yet until you have considered all the options. You may want to PM me re this stuff.

The LIM gaskets require rtv in the corner where the side rail seals meet the cylinder head pieces. Some put rtv along the rail pieces too.

The engine is from a 1997 grand prix and is going to get installed in a 95 Bonneville SLE. The engine has 78000 miles on it.. The car has 72000 miles and this will be engine number 3... Thanks GM...It looks like the larger pipe. I did not get a chance to mic it out, but from operating a tube mill it eye balls at 7/8 in..