gsmith9898

I have a vacum leak on my 525efi. The idle came up about 500 rpm and wierd high pitch sound I take is a vacum leak. I have tried to find it, but no luck. Anyone else had this problem on this motor?

STABIP

If it has an idle air bypass valve that controlls the idle it might be stuck open slightly, or maybe the wire is loose. The valve is a controlled vacuum leak from before the throttle body butterfly to the backside of the butterfly or intakle manifold. When they are bypassing alot of air it will sound like a high pitched whistle.
Good luck..

gsmith9898

sny idea where it is at on the 525efi or what it looks like? I have felt around and even sprayed water with a bottle all around the intake and could not find the source.

gsmith9898

dealer has changed the iac and that did not do it. any ideas?

Dave_N

You might try to remove the flame arrestor and briefly covering the inlet to the IAC passage. That should tell you if the IAC is making the noise.

Dave

gsmith9898

already changed the iac. I gained about 600 rpm so I'm sure it is some kind of vacum leak

JaayTeee

Have you checked the PCV valve or hose ?

here's a pix:
http://www.mercruiserparts.com/Show_...+INTAKE+PLENUM

I'd be checking if item # 9 has became disconnected
or cracked, or split.

gsmith9898

the lines looked fine. mercury racing said to check the plenium but that is o rings so I can't see them leaking. I'm thinking maybe the intake gasket is leaking.

hillbilly24

you can sheck the intake a couple of ways. one is with small busrts of statring fluid around the mating surfaces when the RPM rises you have found the leak. the other way works best if you are a smoker, light a ciggarete and blow smoke around the gsket areas along with where the plenum bolts on and look for the smoke to be sucked in. Caterpillar makes little smoke bombs tat are desgined for this and don't leave any paper or caseing of any kind behind when they are done. You cover the exhuast outlet then light it and put it in the intake then close the throttle body and see where the smoke comes out.

fountainsue

I have a high idle problem on my 525efi, I was wondering if you had any luck finding the problem. I have changed IAC, the throttle sensor and the MAP sensor and none of them worked, still searching... Any help would be greatly appreciated....