Thread: Another leaking LIM post.

Looks like I may need to tackle the LIM gasket issue.

Couple weeks back, I had to flush the heater core, due that it was clogged with the Dexcool/Glycol clay like material. I was successful in getting the heater core unplugged. However I'm still dealing with an overheating issue when driving at slow speeds or idling in traffic. I thought it was an air issue, due to the fact that, if I got on it while driving or revved the engine up the temp would come back down.

I went and bled it again and air did come out from the T-Sat housing.When I looked down into the radiator I could see it was below the outlet for the lower rad hose. But I attributed it too having air in the system. So I topped everything off and marked the expansion tank to see if I'm loosing any coolant. I changed the oil as well to see if it was milky at all. The oil was black/brown, no signs of coolant in with the oil.

When I was bleeding the system, I noticed that I had some Dexcool stains on the top of the tranny on both sides. I followed them up the best I can and it looks like it's leaking in the valley of the LIM.

I've been reading everything I can regarding the LIM and Intake failures. (Mine is a 2004 GT1 with the aluminum intake). However I still have a couple of questions.

1. Is it necessary to replace the Intake manifold gasket for the Aluminum intake? Some posts I've seen it mentioned they can be reused. Is this true or is it better practice to just replace it?
2. Instead of RTV, Can I use the copper permatex sealant for the 4 corners on the LIM? Only reason I ask is that I already have a tube of it.
3. Is the EGR stovepipe still as issue with the newer aluminum intake? Does it burn through the gasket or was it limited to the plastic intakes?
4. Can I use the copper permatex on the coolant elbows as well during reassembly?


Another general question I have about the bleeding process. Wondering if you can explain it to me.

Since the coolant flows from the top of the engine, through the thermostat, into the radiator and into the water pump. Once the thermostat closes and no coolant is flowing into the radiator. Wouldn't the suction from the pump completely empty the radiator and cause air to be introduced into the system again?

The reason I ask is when I was bleeding the system and the thermostat was closed. I opened up the bleeder and no coolant came out. Even if squeezed the hose nothing came out. It was like the upper hose was completely empty. Once the thermostat opened and coolant flowed, air bubbles did come out from the bleeder.

Am I doing the bleeding process incorrectly? I have the cap on during all of this.

1. you can reuse the uim gasket
2. i would use regular rtv..the gaskets should come with a tube.
3. no the egr pipe is not an issue.
4. i would use regular

Tom, Hello neighbor, I'm in Enfield. Awesome post. Seriously, this is a very good post.

A coolant leak where you are describing it, can often be from the end cap on the LIM.


When ordering gaskets, ensure you get that gasket. It's GM part number 24505049 and called "Rear Int Coolant Cover".

Being a 2004 you do have the aluminum upper intake manifold and that should be resued. Only the plastic ones are known for having a problem in the EGR port area, yours will not. The UIM gasket should be reusable, check it for any marks or issue spots.

If that's Ultra Copper permatex, it's the only thing I suggest to people. One of the best you can get that is rated for oil, gas, water and coolant.

On the elbows, I would not suggest RTV. If there is a problem down the road, RTV is a pain to clean out of the coolant elbow holes. I personally like to lubricate the o-rings and that's all.

Originally Posted by BillBoost37

Tom, Hello neighbor, I'm in Enfield. Awesome post. Seriously, this is a very good post.

A coolant leak where you are describing it, can often be from the end cap on the LIM.


When ordering gaskets, ensure you get that gasket. It's GM part number 24505049 and called "Rear Int Coolant Cover".

Being a 2004 you do have the aluminum upper intake manifold and that should be resued. Only the plastic ones are known for having a problem in the EGR port area, yours will not. The UIM gasket should be reusable, check it for any marks or issue spots.

If that's Ultra Copper permatex, it's the only thing I suggest to people. One of the best you can get that is rated for oil, gas, water and coolant.

On the elbows, I would not suggest RTV. If there is a problem down the road, RTV is a pain to clean out of the coolant elbow holes. I personally like to lubricate the o-rings and that's all.

Thanks for the vote of confidence. I try to research as much as I can before posting in an effort to avoid duplicate questions.

Good tip on the RTV on the elbows, I can imagine the nightmare of getting it out. Have a couple more questions.

1. Elbows -What should be used for lubrication? Is it just a matter of hitting them up with a little bit of vasoline before you put them in there or some other product? Same goes for the injector o-rings as well I guess?

2. What bolts for the LIM need to use sealant for re-installation. Use loctite blue for the remainder?

3. Are there any locating dowels for the LIM? If so, do they have tendency to come out when removing the LIM? Last thing I want to happen is have a locating dowel find it's way down into the lifter valley.

For the LIM gaskets, I was going to go with the Felpro set from Autozone. Is this the updated set? (Non-Plastic) Felpro/Intake Manifold Gasket (MS98014T) | 2004 Pontiac Grand Prix 6 Cylinders 2 3.8L SFI OHV | AutoZone.com

1. I have a tube of vasoline in my goop drawer of the toolbox for exactly that and yes on the injector o-rings as well.

2. The 12 bolts that hold the lim to the heads/engine. I wire wheel them clean, a quick spray of brake cleaner to take any leftover oil off them and then dab them with some teflon paste. Likely you can find it at a parts store. I found my current super sized container at Home Depot in the plumbing aisle. I do not and have not read up on using locktite on any other bolts. The manual does suggest using blue on the LIM bolts, but techs suggested the teflon based goo instead because it seals better. The bolts aren't going to back out on you. PS 15ft lbs.

3. There are no dowels from the LIM to engine. I sit it in place via eyeball on the bolt holes and then start all bolts by hand before snugging any one bolt.

Side note: The UIM gasket has two dowels built into it to help located it on top of the LIM. The LIM end seals have locating pins to help keep them in place. Take a look at this thread, your engine block is the third picture down known as the second design. http://www.grandprixforums.net/lim-g...ign-39522.html

LIM Gaskets, sure those will do fine. I would suggest finding a discount code. i do most of my ordering with Advance and use discount code CCABIN. If you got the intake gasket set MS98014T, elbows dorman 47065 (Enfield store stocks them), coolant and oil then you'd be over $100 and the code would take $40 off that.

Bill - Thanks for pointers and the discount code. I think I may have the same Home Depot sealant already. I picked some of the grey goop about 4 weeks ago when I was replacing a couple of water shut off's for the washing machine in my house.