Determining Intake Manifold LEAKS...easiest way?

[gmrulz4u]

Besides the obvious symptoms of an Intake Manifold leak, is there any trick, or easy way to determine one's engine has this problem?

 

I'm almost 100% my 2.8L Supreme does, but I just want to know if there's anything visible, or audible etc...for me to look for?

 

THANKS:)!

 

Also, how easy or expensive is this job to get fixed?

[JS91Z34]

Use some carb or TB cleaner and spray around the intake area and listen for a change in engine sounds/RPMs. Propane works good too!

[no1kicker]

wd-40 also

[toastemcutlass]

sounds stupid but did you check your vaccum lines on top they always come out, or are loose.

[gmrulz4u]

OK, I hate to sound stupid, but where EXACTLY should I spray it? If anyone could show me a pic with an arrow or something, it would be greatly appreciated!

 

THANKS

[JS91Z34]

spray at the gaskets between the lower intake and the heads and the gasket between the upper and the lower intake. Also spray the vacuum lines and acessories that have vacuum lines going to it.

[Slade901]

You may also use a Starting Fluid as well where others have suggested including the base of the TB (Throttle Body).

 

If there is any leak then the Starting Fluid, TB Cleaner, Carb Cleaner will be sucked into the leaking area and will change the IDLE Speed.

 

 

One way to test for a vacuum leak would be to remove the air cleaner/hose and slowly cover the TB throat with your hands (choking the engine a little bit). If the IDLE Speed increases then you have a vacuum leak, but if the IDLE Speed decreases or engine stops then you might not have any leak.

 

Another way to find any vacuum leak would to be use a 3/16" rubber vacuum line. With the rubber vacuum line, just put one end around the intake manifold, vacuum hoses, base of TB, etc and then put other end of the hose to your ear. You will hear a hissing sound if there is a leak.

 

I would still use the Starting Fluid, TB Cleaner, Carb Cleaner to find leaks and very small leaks as well as using a 3/16" rubber vacuum hose. 8)

[boostnawd]

Yet another way, and those of you with turbo cars may know about already, is to pressurize the intake. If you have access to a compressor, shoot a few psi into the intake tract (what I did was fab up a connector out of styrofoam with a inner tube valve in the middle.. it goes on the intake side of my turbo and is an air tight seal), holt the throttle plate wide open (WOT) and listen for hissing.