Find vac leak

[McLin]

Hi,

how can I find a vacuum leak?

I hear hissing from driver side. I used 2 cans of starter spray and on throttle cleaner. No change in rpm.

I'm on the of my Latin. If I pull the throttle short and raise the rpm I hear a loud air soak. But I can't locate it. Can be the egr, lower intake upper intake or fuel inceppjector. I begin to hate the car.

[Schurkey]

Define "Driver's side".

Driver's side of the ENGINE, or driver's side of the ENGINE COMPARTMENT.

If it's far enough over to be more engine compartment than the engine itself, I'd be looking at the brake booster, cruise control, interior HVAC plumbing, and perhaps a vacuum reservoir, which on earlier cars was tucked under the fender ahead of the left front wheel, but may or may not be in that location on your car.

EGR is probably electric, not vacuum.

[McLin]

Driver side between throttle body and egr. There is the hissing on loudest. On my 3.8 V6 is there nothing. Just the end of upper intake plenum, the egr tube and lower intake. But I told you I spray all the cans in all areas and there was no change on rpm.

If I plug off the egr valve there are 2 vacuum tubes.

[Schurkey]

I'm sorry--I'm not familiar with the 3.8L.

[Tech II]

What year and engine?

[McLin]

98 3.8 V6 Series II

[Tech II]

Not sure what you are talking about....the EGR is electronic, and has no vac tubes going to it.....

The only vac lines on the car from the throttle body go to the fuel pressure regulator and to the purge valve.....there is a vac line on the back of the upper plenum that goes to your brake booster.....

[McLin]

Hey,

plug off your egr and hold your hand over the holes and a 2nd man starts the engine, and you feel the vacuum. It's the tube from intake manifold to egr.

[j cAT]

Originally Posted by McLin

Hi,

how can I find a vacuum leak?

I hear hissing from driver side. I used 2 cans of starter spray and on throttle cleaner. No change in rpm.

I'm on the of my Latin. If I pull the throttle short and raise the rpm I hear a loud air soak. But I can't locate it. Can be the egr, lower intake upper intake or fuel inceppjector. I begin to hate the car.

vacuum leaks with the upper intake gaskets etc can be a problem to find. with this I will use propane gas to locate these leaks. spraying fluids can be dangerous and destructive to electrical s .

using a small hand held propane torch you install a long rubber hose to the torch end. then turn the valve open to allow a small amount of gas to come out. then probe the engine waiting to hear a rise in RPM. best using a hand held tach to see any RPM shift.

to test this place the hose leaking the propane into the air intake and you will see the rpm rise.

with this type engine around the 130,000mi point the intake manifold will fail where the EGR is. the intake manifold is not properly designed to handle the exhaust gases temp. then the intake manifold will crack internally causing the MAP to go off and then the engine will run extremely rich at first then not at all..