LIM Rubber or Plastic?

happydog500 · 10-19-2007, 08:00 PM

I went in to get a lower intake manifold gasket for a 97. The guy asked me if it was rubber or plastic (I believe this is the two end pieces, not the gasket itself).

I asked witch one was better, thinking I'd get the better one. He explened that it wasn't a choce, it eather had plastic or rubber.

He looked it up and told me durning the year GM switched the end gasgets. There is something else different about it also. Something about something sticking out?

I have never heard about this before. Does anyone know anything about two different parts used in 1997 for the LIM gasket?

Thank you,
Chris.

BNaylor · 10-20-2007, 08:41 AM

Was this at a GM dealer or an auto parts store? I'm surprised you weren't asked if you have the pinned or unpinned LIM gaskets. GM does have the revised LIM gaskets out for the '95 and up GM cars with the SII 3800 engine. See link below at Buick Tips & Maintenance.

Click here

happydog500 · 10-20-2007, 04:22 PM

Yes, that's what they asked me. Pined or not. He said they changed during the year, so some are one way and some are the other.

Problem is a friend and I will do the job in the evening, after his work. We will have to wait until we get it apart to find out which one it is.

That may add another day to the job if we can't get to the parts store before they close.

Chris.

BNaylor · 10-20-2007, 04:43 PM

From what I understand whether you will need the pinned or unpinned will be based on inspection after the disassembly. I have no clue as to whether you can tell otherwise. Whether you need the pinned will be obvious because you will see the rubber tits on the old gasket and the corresponding index holes on the block where the LIM mounts.

What I do know is the orange end piece gaskets look like polymer based rubber which is typical of composition gaskets on the market. Also, it is important to make sure you use hi-temp RTV silicone sealant at the 4 corners where the end piece gasket meets the port gasket on each bank.

Good luck!

happydog500 · 10-21-2007, 02:42 AM

I just got back from the friends house. He told me he isn't going to use the end pieces. I couldn't believe it. He said he has done it a "million times" without it.

He is going to put some Blue stuff instead of the end piece.

I do know this guy is good. He builds Hot Rods, has hoped up motors all over his garage.

Have you ever heard of not using the end pieces?

Chris.

BNaylor · 10-21-2007, 09:59 AM

Personally, I would use the end pieces but if this guy is that good or knows what he is doing then it is up to you since you trust him. That is not an uncommon practice for engine builders. Below is a pic with the port and end piece gaskets installed just for reference.

Also, be sure to get a new 90 degree coolant plastic elbow with the two o-rings. The part that goes between the tensioner and LIM for the heater bypass. Once the tensioner is removed you may find the elbow will break during removal or be deteriorated.

happydog500 · 10-21-2007, 11:44 AM

Thanks for the picture, that's cool!

I wish he would use the end piece. When I told him that he said, "what problem does this motor have?" I said they leak. He said that's why where not using them.

I want him to use them, but he says if we do, he won't do the job.

I am confused on the torque for the LIM. Why do they have so many different sources saying different specs? I may put it off another week to find out, but the O2 Sensor went out and this motor is losing fluid.

Thank you again for the picture, Chris.

BNaylor · 10-21-2007, 12:13 PM

You're welcome. The LIM bolt torque is 11 lbs-ft or 132 in-lbs per the FSM. If you plan on reusing the LIM bolts make sure any old threadlocker is thoroughly cleaned off or removed. Use medium strength threadlocker (blue) on the LIM bolts. New GM replacement LIM bolts will have the threadlocker already applied. Loctite or Permatex brands work fine.

It sounds like you are in weird predicament since he is doing the work. Are you paying him for the labor?

HotZ28 · 10-21-2007, 09:22 PM

I have not used end seals since the invention of high temp silicone. I also use silicone (either red or blue) and have never had even the slightest leak from the manifold ends. I have not built "millions" of motors, but I have built my fair share in the past forty years!

BNaylor · 10-21-2007, 09:31 PM

I've built quite a few GM engines especially of the small block V8 variety and Chrysler big blocks mainly for racing but on the GM 60 and 90 degree engines I think I would use the end seals in the gasket set. They are problematic enough with the known UIM and LIM problems. Plus I hate doing a job a second time.

If the silicone sealant is used in lieu of the most important consideration is giving it the proper cure time which is typically 24 hours or more before even starting the engine up.

happydog500 · 10-22-2007, 03:10 AM

Quote:

Originally Posted by BNaylor

The LIM bolt torque is 11 lbs-ft or 132 in-lbs per the FSM.
It sounds like you are in weird predicament since he is doing the work. Are you paying him for the labor?

132 is the original torque, what about the "updated" specs?
He is doing the work for free. He is a good friend. If I could figure out how to post a picture here, I could show you a nice car.

BNaylor · 10-22-2007, 08:44 AM

I'm not aware of any revised torque specs on the LIM bolts which has been 11 lbs-ft/132 in-lbs for quite a few years now. However, GM did revise the torque spec on the UIM. As of June 2004 GM recommends 11 lbs-ft or 132 in-lbs on the UIM bolts. I did a '98 Bonneville (na SII 3800) back in January and used the revised UIM spec but used the same old LIM spec. The old UIM spec was 89 in-lb.

happydog500 · 10-22-2007, 12:00 PM

OK, I got the Upper and Lower mixed up. Thanks for clarifying. I really want to show you my friends motor. Will figure it out.
Thank you for your reply,
Chris.

POST REPLY TO THIS THREAD