Swapping a L26 Aluminum Intake Onto The L36 Engine

[pcmos]

No Boost,
Thanks so much for contributing your experience on the matter, when I look at your project photos I can see that you installed a valve cover vent. Is there something about doing the intake swap that requires the use a valve cover vent or was that simply an unrelated modification? I'm also wondering if you can see any reason why I should continue researching the use of the L26 lower intake instead of just using another L36 LIM. If the PCV system will work fine after mating the L26 UIM to the L36 LIM then theres probably no reason for me to worry about using an L26 LIM.

bnaylor,
I'll do a full report on the project when I finish and post it to the tech tips section (also in PDF form). Please forgive me though if it takes me a few weeks to get going on this, I'm still suffering from a little post traumatic stress disorder after the transmission rebuild After I get back from a vacation in a couple weeks I'm going to order a new L26 intake and get started.

[happydog500]

OK, Sounds good.

I have 150,000 on my original GM Plastic UIM. I run my 97 like a race car on the street. If I get anywhere near the life I got from the stock, I'll be happy.

[No_Boost]

There's absolutely no reason to explore the L26LIM option IMHO any further. You will not gain anything from it as far as performance, and I do not believe there's any significant difference between the L36/L26LIM's. The only one possibility is the EGR stack... and the solution to that is a hacksaw!

As for the breather cover... totally unrelated to the L26UIM swap. No need for it.

Like I said, there's only the need for a TB adapter and shortening the EGR stack. Stock L36 gaskets work fine.

Where is the leak you're getting on the LIM? One of the most common causes is lack of sealant (Right Stuff by Permatex) in the corners of the sides gaskets (4" long either side between the LIM & UIM). Lots of ppl either forget it, or don't know about putting it there.

happydog, you're lucky getting 150k... most don't make it to 80k!

[pcmos]

I went back through my shop documentation and I don't see anything about using a sealant along the sides of the LIM, but it looks to me like the dealer did use some sort of RTV since there are globs of it all over the sides of the LIM and block. The leak that I have seems to be coming from the rear edge (long edge) but more towards the drivers side rear corner and its definately oil. When i pulled the transmission from the engine and took a look in there its cascading down the rear and drivers side of the engine and dripping off the oil pan. At first i figured it was a rear main seal leak based on the fact that i was seeing oil collect on the flywheel cover and oil pan but after getting the transmission pulled im convinced its leaking from the LIM or perhaps is a valve cover leak. It can't be a cylinder head gasket leak because theres oil soaked grime above the level of the head gasket, assuming oil can't leak upward then i think its safe to rule out the head gasket. Either way ive definately got coolant pooling up around the front of the engine from the intake so I plan to replace both intakes and the valve cover gaskets and probably all 6 fuel injectors (for no particular reason).

[BNaylor]

What shop documentation are you referring to? I recall if it is GM FSM material sometime in 2000 and up GM may have omitted the mention of RTV at the corners where the end seals and port seals meet. Now on older 1999 and under FSM material the RTV part is there in black and white. I'll be happy to send you what I have on the UIM/LIM in a PDF file. I can't post it here due to copyright.

Unless you are having problems with your fuel injectors replacing them could be a waste of money but it is up to you. Definitely replace the upper and lower o-ring seals.

[pcmos]

I have the SI 2004 software from GM and I have the print version of the GM OEM shop manuals specifically for my 2000 LeSabre and I can't find any mention of the use of sealant. I checked the SI software for a 1998 LeSabre and theres still no mention. They do mention using threadlock compound on the LIM bolts. I can see how it would be a good idea though, I probably would have used some anyway.

[BNaylor]

Yeah there are definitely discrepancies in the GM documention. Here is what I have. As you can see there is an extra annotation on page 2: "Apply GM approved sealer to the ends of the intake manifold seals."

Click here

Also, I noticed the UIM bolt torque figure changed. In older documentation it says 89 in-lbs. In newer it says 11 ft-lbs (132 in-lbs).

[pcmos]

Wow thanks for showing me that information. It gets really frustrating when you think you have the latest documentation available and then you find out theres more. Half the time I spend working on cars these days is spent trying to work against the efforts of the manufacturers to keep that information out of my hands. If you have any advice for me on how to purchase more recent service information please let me know. Thanks again for the heads up.

[pcmos]

Just to post an update, I placed the order for my L26 Aluminum Upper Intake manifold from gmpartsdirect.com. Aparently it's a special order part so it may take a while for me to actually get it.