I have a 2001 Monte Carlo ss. The LIM had a slight leak, so I replace the gasket (Plastic) I torqued acording to book. Had a vacumm leak. Did a little research and found new torque specs and sequence, and replaced the gasket again. Sill had a vacuum leak. Not one to give up I purchased the new Felpro Steel LIM gasket, had the intake checked at machine shop, replaced intake manifold bolts, triple checked the bolt hole threads to make sure they wer clean installed the new gasket and torqued the bolts to 12 lbs, as suggested by my mechanic. Stll have the same vacuum leak on the rear drivers side of the engine. Does anyone know the torque specification and sequence when using the steel Felpro MT98014T gasket.

 

Start in the middle and work your way around...cirss crossing each bolt..also do it in 2 sequences instead of doing it all at once...

 

I used the standard torque pattern. Torque to 6 pounds then 12 pounds.

 

Maybe you have a warped head etc?

 

Are you sure it's the LIM that is leaking? All your injectors seated correctly? Uim where it meets the like is in Good condition, not cracked or anything?

 

I'm with Budsjlm.... Somehow, I'm not sold that the leak is the LIM. I assume the heads and intake are not modified and that when you set the LIM gaskets in place, the guide "pins" on the gaskets slide into the heads like they should and the gasket was resting flat???

You have spark plugs, injectors, the entire plastic UIM, big huge brake vac line..... How are you testing for the vac leak and can you narrow it down a little more then the back of the engine?

 

To test it I am pulling a plastic coffee can over the throttle body (runs smooth) and spraying around the rear of the intake. The engine starts to run rough 2 inches from the brake vacuum line. The UIM is new. The head is steel, seems like the intake would warp first. It's not so bad but I've replaced a dozen manifolds in my life time and never had a problem. New o rings on the injectors.

I will double check things maybe I am focusing to much on the LIM as being the problem and not really seeing the problem.

 

I would double check the vacuum line. 2" away is close enough for it to be sucking in the mist and altering the idle.

 

Got it. Used some gear oil with clear hose instead of spray to find the problem.

I left the alternate braket off (pain to put on and havr yto take off). The bolt hole in the head goes into the intake port big vacuum leak. Wish I would have got on this forum 2 years ago when I first tried to fix it to nice of a car to be sitting up. Thanks to all!!!!!!!!!!!!! I would have still been trying to fix the LIM.

 

Good to hear you found the problem and got it fixed. Now go enjoy your ride!