intake manifold vacuum leak

[tex87]

i have a 2005 mustang gt
wrecked it and swapped my motor into another body (nothing was damaged but the body ) ... was running fine before the swap ... did the swap and it starts and runs fine ( i am cammed and tuned )
after it heats up iam getting a stumble in low rpm ranges in all gears ... did a smoke test and found that i have a leak on the passenger side very rear corner of the intake manifold ...
swapped another intake manifold and new gaskets once agin and still there is a leak ... wtf ???? could my head be warped on the top ? where the manifold sits on it
stuck ,lost and confused here please help lol iv invested too much in this allready and reallly cant affourd to keep dumpin money in this thing

 

[07 Boss]

I would double check the O-ring gasket to see if it may have gotten crimped or something during the install.

Is it a big leak? I'm asking because maybe a small dab of RTV might fix the issue. Now you shouldn't really use RTV with O-rings but a small bit may help it seal up. That would be the cheap band aid. Other wise you would have to go get the heads and manifold checked to see if whether either or is warped for some reason.

 

[Autokyrios]

Check what Boss said. If you reused the gaskets, don't. They're cheap so just grab some new ones (CJ/LMR/etc). Make sure the gasket grooves are clean and clear. Debris gets into them easily and it's not always easy to see.

Check your bolt holes in the head to make sure they're not stripped and things are seating. Make sure the manifold mating surfaces are clean and flat (use a straightedge and a light.

Do a smoke test on just the manifold to rule it out (tape things off good and blow smoke in the EVAP port). Cracks can happen.

As for the head warping...Was anything done to the engine? Rebuild? Surfacing? Idiot with a sanding disc watching too many youTubes?

 

[86GT351]

Remove the intake and replace the gaskets. Inexpensive to do.

 

[Laga]

Instead of RTV, use a light coating of silicone grease. It holds the gaskets in place and allows a little wiggle room when installing manifold without the gaskets moving.

 

[MasterofDisaster]

silicone grease

I heard from Ford mechanic that silicone lube will eat 02 sensors. I don't know if that's still true, but I try to avoid it anywhere that might end up in the exhaust.

 

[GriffX]

I heard from Ford mechanic that silicone lube will eat 02 sensors. I don't know if that's still true, but I try to avoid it anywhere that might end up in the exhaust.

If silicone oil or grease gets through the combustion it will be burned to sand, so basically ash. You must burn a lot to damage something.

 

[JC SSP]

Hmm I have always used those "O2" safe silicone sealers recommended by the manufacture...

 

[Laga]

I heard from Ford mechanic that silicone lube will eat 02 sensors. I don't know if that's still true, but I try to avoid it anywhere that might end up in the exhaust.

I had a Ford mechanic tell me I needed to get a stainless steel gas tank if I wanted to convert to E85.
My 05 was built in early March. The first S197s did not have the feature where you could lower the windows with the remote fob, but It could be activated by a dealer tech. When I talked with the service department to set up an appointment. They didn’t not know about it. I had to print out the information from the Ford forum I was on at the time for them to do it.
I take everything a dealership tech tells me with a grain of salt.

 

[Autokyrios]

Point of the matter is unless you're loading those gaskets up with silicone I doubt you'll have a problem.

But to be clear, I've never used anything on my intake gaskets. Cleaning the gasket channels and mating surface, using new gaskets and making sure they are tucked in neat, works just fine.

 

[StockishS197]

If you want a cheap and easy way to check for leaks, try this method:

Fluid transfer pump + black and mild cigar - seal off TB and pump cigar smoke into one of the vacuum port ports, then follow with a small amount of compressed air and find your leak.

Just tried this over the weekend and works great for less than $30.