Write-Up: Lower Intake Manifold (LIM) Gaskets

I replaced mine a few years ago and it wasn't too bad. Just time consuming. The gasket doesn't come with rtv so you will have to buy it. I removed the plastic vacuum lines from the tee and left the tee on the manifold. I have heard stories about the tee fitting breaking off in the manifold. Here is the thread that mentions some of the part numbers that you will need. https://rivperformance.editboard.com/parts-wanted-f23/part-number-listing-t45.htm. About half way through the thread you will find a post from me asking for part numbers. I was also replacing the pulleys at the same time, but all of the parts that I got are listed in that thread. I removed the throttle body when I changed my LIM gasket because I wanted to clean it. I would also change the valve covers now because it will be much easier access to the valve covers.

Thanks guys, what about our injectors, whats the trick, do ya yank on 'em or twist and slide. Are they held in with a clip.....?

Clips are for the wiring connection (disconnect). The injectors should pop out with the rail. They're held in by compression from an O-ring on each injector.

BMD wrote:

Thanks guys, what about our injectors, whats the trick, do ya yank on 'em or twist and slide. Are they held in with a clip.....?

as aaron said unplug the harness from each injector, then take a small pry par and gently pry up on the rail near the injectors not on them, i usually pry off the rocker cover in a few different spots until the front is loose and then i see if the back is loose and if its not then pry back there as needed.

I didn't have to use a pry bar or anything to remove them, but they are in there pretty good. This is from the clubgp write up: "Once you remove all the bolts holding the fuel injector rail down, using the metal stub sticking out (that I circled in yellow), lift up, and the injectors will pop out of their sockets. For the rear sockets there is a stub too. To remove the rail, I found it easier to lift the passenger side first and slip the rail out from underneat the vacuum lines."

Of course, don't forget to unbolt the fuel rail first (five bolts hold it down). IIRC, there is a small clip that holds them into the fuel rail. So if you want to remove them from the fuel rail you will have to remove the little clip. It just slides out. I changed both the top and bottom o-rings on the fuel injectors when I changed the LIM for safety and the o-rings were cheap.

BMD,
I've read some of your questions and wanted to offer the following:

If you don't have the proper GM Engine Sealant P/N 88861417 that is used in the corners of the Intake gasket where they meet the orange valley gaskets, you can use a sealant made by one of the other companies like Permatex, I can only remember Ultra Grey something or other. Maybe Abaddon can be more specific. It is supposed to be the same as the GM stuff. I ordered a tube of the GM Grey Sealant but could have bought a tube of the Ultra Grey for less.
You want to apply some in the corners only to prevent a leak. Do not use any old RTV, they are different.
Also, be sure to have a small pick or something to check the holes in the cylinder heads where the Fuel Injectors come out of for any O-Rings that may be down in the holes. Then use some Q-Tips with cleaner on them to clean the holes before re-assembly. You can use Brake Clean for these also. I would recommend having a couple of cans handy, if you don't already. I also had a couple of cans of Carb Cleaner to clean the inside of the LIM and removed the carbon build up. Do Not use Carb Clean around painted parts as it will ruin paint and don't use it on any sensors.
The fuel injector O-ring's from Fel-Pro are a very good replacement for the GM O-rings and are much less expensive. EDIT: I ended up getting "Standard Parts # SK9, Seal- O-Ring" from my independent auto parts store. Same a Fel-Pro or any other parts that are available to you up there.
GM retail for an O-Ring Kit is about $50.00 and the Fel-Pro o-rings are less than 10 for the total quantity needed. They don't sell a Kit, they just sell them by the box and if I remember correctly one box does not contain enough o-rings, so be sure you get enough. And you can use a little motor oil to lube them for re-assembly or you can use dielectric grease, which ever you have.
The plastic elbow can be purchased at your local auto parts store. They are carded and come with 2 different ones per package with o-rings already installed.
They are packaged and in the HELP section as Heater Hose Fittings P/N 47065. Use the correct one out of the package that matches the one you are removing. Replace it regardless if you break the old one or not as they tend to get brittle from age and the o-rings dry up and shrink. Good PM to replace now and lube the o-rings on that with Anti-Freeze.
You do want to remove the supercharger before removing the LIM for easy access to the LIM bolts. Clean all LIM bolts with a wire brush and some spray cleaner like brake clean and before re-installing coat the threads with some pipe sealant with PTFE, also available at the auto parts store or GM P/N 12346004. Do not need to use too much, just enough to help stop the oil from wicking it's way up the bolt threads during normal engine operation. Too much pipe sealant will effect the proper torque on those bolts as well. All I can say is use enough, but not too much.
I can't think of any other tips other than to replace your heater hoses while the LIM is off. They are extremely difficult to do when the engine is together and if they have never been replaced before, now is a good time to do them. Just make sure you use a sharp razor blade to cut them off the heater core tubes so you do not damage the core by pulling and twisting the hoses. Be as delicate as possible. You can re-use the OEM clamps. I got one hose from my regular auto parts store and the other from NAPA, so they are available - you just may need to give the store a day or 2 to get them in. Try NAPA for both of them.
Good Luck and any other questions, don't hesitate to ask.

Great advice guys, I need to start assembling parts and figure out what weekend I can tackle this before the cold starts. The Rivs' my daily driver and can't afford to have her out of commission too long. I just don't trust a GM dealership ( no offence to any mechanics here) to not crack or break something and not tell me about it, let alone scratch up my fender. If I have any more questions I will poste 'em, and if anyone remembers anything else, please share, thanks again!

Are you interested in doing the mod that blocks off the coolant flow from the LIM through the Throttle Body.?
It involves drilling, tapping and plugging the 2 holes in the LIM.

I originally bought the SC gasket from the dealer, it did not come with the 2 O-rings that go under the SC. The dealer did not have them and would have to order them. I bought the felpro kit for the SC from autozone for less than the GM gasket, and it came with the O-rings. I also noticed the GM gasket and the felpro were identical, same brand material. The only difference was the GM one had a GM P/N stamped on it.

Thanks for that tip David. I think I am going to keep her stock Rick. What is the benefit of that though?

moldymac wrote:

I originally bought the SC gasket from the dealer, it did not come with the 2 O-rings that go under the SC. The dealer did not have them and would have to order them. I bought the felpro kit for the SC from autozone for less than the GM gasket, and it came with the O-rings. I also noticed the GM gasket and the felpro were identical, same brand material. The only difference was the GM one had a GM P/N stamped on it.

You are correct about the Fel-Pro and GM Paper type Supercharger gaskets. There is money to be saved and the Fel-Pro gasket does come with the O-Rings where the GM does not. I could not tell the difference between the 2 gaskets.
But if you are going to plug the holes then no O-Rings are needed.
Tap the 2 holes to accommodate 1/4" NPT flush pipe plugs and seal with pipe sealant.
I just wish Fel-Pro sold the Aluminum LIM gaskets. I had heard that they do, but my local auto parts store ordered the Fel-Pro LIM gasket set for me and it was not the Aluminum gasket that the GM one was. I should have tried ordering one for a 04 GTP and maybe that would have been what I was looking for but I forgot at that time.

I was recently (within the past two weeks) told of an Aluminum Supercharger gasket that is available through GM. I do not have the P/N for this gasket and have not seen one nor used one. Not sure about the necessity of it though as I have not heard of a problem with the SC gaskets like we have known about with the LIM gaskets. I'll assume it can be found by looking up the GM P/N for a 2004 GTP possibly. But I'm not sure.
It came up in conversation with Bill Boost a couple of weeks ago, regarding a GEN V install, but didn't have the time to ask all the pertinent questions. He did say that he is using the new style on all SC and LIM changes - I just don't know why yet.

EDIT: Never mind about the Aluminum SC Gasket, I was confusing the GEN V with the stock M90 SC. Any reference to 04 GTP would be a GEN V and L32 LIM.
Sorry if I confused anyone, I seem to be confusing myself lately.

BMD wrote:

Thanks for that tip David. I think I am going to keep her stock Rick. What is the benefit of that though?

The Hot Coolant travels through the intake manifold and up through and around the opening of the Throttle body normally, as designed by GM engineering.
Presumably to heat up the inlet of the Throttle Body when the engine is cold and keep the inlet air temp the same as the engine coolant temp.
The extra heat at the Throttle Body has been determined by some in the modification world to be a detriment instead of an advantage.
So, to keep the inlet air temp down some, you just have to block off the coolant from passing through the Throttle Body by plugging the 2 ports in the LIM that are sealed from leaking, during normal operation, by the O-Rings.

It makes sense and is easy to do, doesn't cost much and doesn't affect the coolant flow through the rest of the engine at all. Basically, it is a simple and cheap mod to help keep inlet air temps down. Just involves tapping, sealing and installing the 2 plugs.

Rickw wrote:

...You do want to remove the supercharger before removing the LIM for easy access to the LIM bolts.

Clean all LIM bolts with a wire brush and some spray cleaner like brake clean and before re-installing coat the threads with some pipe sealant with PTFE, also available at the auto parts store or GM P/N 12346004. Do not need to use too much, just enough to help stop the oil from wicking it's way up the bolt threads during normal engine operation. Too much pipe sealant will effect the proper torque on those bolts as well.

I can't think of any other tips other than to replace your heater hoses while the LIM is off. They are extremely difficult to do when the engine is together and if they have never been replaced before, now is a good time to do them. Just make sure you use a sharp razor blade to cut them off the heater core tubes so you do not damage the core by pulling and twisting the hoses. Be as delicate as possible. You can re-use the OEM clamps. I got one hose from my regular auto parts store and the other from NAPA, so they are available - you just may need to give the store a day or 2 to get them in.

- Ah-ha... access to the LIM bolts. Duh! I guess that SOMEtimes the FSM guys get it right...
(We can leave the alternator-bracket/tensioner/heater-hose-conduit in place, though, right?)

- OK, I can see sealing those bolts...

- I was thinking the same thing about the heater hoses, even though I've already bought the super-clamp-pliers...
Rick, would you also say that this is a good time to renew the rocker-cover gaskets (especially the REAR)?

Rickw wrote:

Are you interested in doing the mod that blocks off the coolant flow from the LIM through the Throttle Body.? It involves drilling, tapping and plugging the 2 holes in the LIM.

Actually, I believe that ZZP, etc. offer gaskets that block off that TB coolant flow....

However, I was researching it on the Net and probably here as well, and some folks said that it reduced coolant flow to the rear head... My (unanswerable) question is this: If we have those nice big passages in the intake manifold, plus a 'bypass' on the driver's side of the intake manifold, beneath that cover with the 2 bolts, is the flow through the TB that important?

Those of us who live south of snow country would probably want to get rid of that extra KR heat in the TB by blocking off the passages with a simple gasket change, but on the other hand, if cylinders 3 & 4 are already too hot, are we "playing with fire"?

Eldo wrote:

Rickw wrote:

...You do want to remove the supercharger before removing the LIM for easy access to the LIM bolts.

Clean all LIM bolts with a wire brush and some spray cleaner like brake clean and before re-installing coat the threads with some pipe sealant with PTFE, also available at the auto parts store or GM P/N 12346004. Do not need to use too much, just enough to help stop the oil from wicking it's way up the bolt threads during normal engine operation. Too much pipe sealant will effect the proper torque on those bolts as well.

I can't think of any other tips other than to replace your heater hoses while the LIM is off. They are extremely difficult to do when the engine is together and if they have never been replaced before, now is a good time to do them. Just make sure you use a sharp razor blade to cut them off the heater core tubes so you do not damage the core by pulling and twisting the hoses. Be as delicate as possible. You can re-use the OEM clamps. I got one hose from my regular auto parts store and the other from NAPA, so they are available - you just may need to give the store a day or 2 to get them in.

- Ah-ha... access to the LIM bolts. Duh! I guess that SOMEtimes the FSM guys get it right...
(We can leave the alternator-bracket/tensioner/heater-hose-conduit in place, though, right?)

- OK, I can see sealing those bolts...

- I was thinking the same thing about the heater hoses, even though I've already bought the super-clamp-pliers...
Rick, would you also say that this is a good time to renew the rocker-cover gaskets (especially the REAR)?

I removed the alternator, but I left the bracket in place. I would change the valve cover gaskets if they haven't been changed in a while. If you decide not to change them, it isn't the end of the world if you have to do it later. It is just easier to change them when you have everything removed for the LIM gasket. The valve cover gaskets come in pairs, so you would change them both at the same time.

Having plugged the TB coolant ports in both the series 2 and one, I can say there is really no "playing with fire" involved. These holes are quite small, and when taken that on the series 2 the coolant has another route it can take, the flow is pretty low. Liquid likes the path of least resistance, and on the series 2 there is more resistance to go up through the tiny coolant holes into the TB and back to the rear head. Add to that the ease that you can open under the bypass cover to match(or more) the "lost" flow; you might as well do it.

IIRC, I usually use 1/4" boiler plugs and a 1/4" NPT tap.

That said(even though this is the series 2 section), I'd like to stress something I have found about the series 1 that I haven't found mentioned anywhere on the net on sites that like to discuss the series 1. If you plug the holes on series one, you will stop ALL coolant flow through the middle passage of your LIM.(series 2 doesnt have this passage). To plug them, you need to break through the passage wall to maintain normal flow.

its hard to visualize "breaking through the passage" wish i could see that?....

robotennis61 wrote:

its hard to visualize "breaking through the passage" wish i could see that?....

I'm doing a LIM for hometown hero shortly, I'll get pics and post it in the appropriate form then.

I was studying the motor to see if there is anything else I forgot to ask. The flexible fuel lines that run to the tank slide into the fuel rail on top of the motor, how do you get those out? I'm sure they will break if you try and slide them off, and they are a good inch on there.

There is a fuel line release tool that you need to get those apart. You can buy a cheap one at your local auto parts store.

Here is a link to one
Link

You can also buy the diffrerent colored plastic ones for all sizes, come as a set. You can see those at the bottom of that page.
That round thing on the fuel rail is nothing but a spring that needs to be expanded to release the line.

Thanks Scott. How does the tool work? I was wondering though, if you could just leave the lines attached and rotated the fuel rail up towards the windshield?

You *can* leave the lines attached, but it is REALLY not recommended. Your chance of kinking(and a kink rapidly turns into a split) the plastic line up farther are like 95% if you just move it up and out of the way (experience is talking here).


The fuel line disconnect tool just attaches around the hose, and slides into the connector pushing aside the tabs that hold it together.

BMD wrote:

Thanks Scott. How does the tool work? I was wondering though, if you could just leave the lines attached and rotated the fuel rail up towards the windshield?

There is a round spring inside that round piece. It's tight around the flange on the fuel line. That release tool simply pushes in and expands the spring in order to pull out the line. Once you get it apart, you can see exactly how it works. Quite simple actually....

And, as Karma has said, NOT RECOMMENDED to leave the fuel rail connected. You risk the chance of kinking or breaking a fuel line.

Buying the proper tool at the Auto Parts Store is soooo much cheaper than having to replace the rigid plasic fuel lines.

The tool is between $5.00 and $10.00 dollars and the line to replace that is about $50.00 to $100.00 if you pay someone to replace it for you. Closer to the $100.00 at a dealer.

I would buy the inexpensive tool and remove the lines properly, they are a no brainer with the tool.

Gotcha guys . So once that spring is expanded, the line should just slide off? or will it need to be coaxed?