Hissing noise

Post Sat Oct 27, 2012 12:30 pm

I have just refitted my inlet on my m52 ( m50 inlet)
I'm getting a. Hissing noise from around the fuel pressure regulator when I switch off the engine.
It only last a few seconds but I can't remember hearing it before.

The small hose from the regulator to the inlet is fine.
Can anyone help?[/quote]

Post Sat Oct 27, 2012 1:20 pm

Only place there should be a vacuum after the engine is stopped is in the brake servo, so turn your attention to the servo hose and its one way valve.
Alternatively, it could just be the fuel pressure regulator. They can make some strange noises if the fuel pump is running without the engine.

Post Sat Oct 27, 2012 1:52 pm

Brianmoooore wrote:Only place there should be a vacuum after the engine is stopped is in the brake servo, so turn your attention to the servo hose and its one way valve.
Alternatively, it could just be the fuel pressure regulator. They can make some strange noises if the fuel pump is running without the engine.

Does sound like the regulator is making the noise.Is it a problem if it is the regulator?

It sounds like the regulator is releasing pressure .

Post Sat Oct 27, 2012 7:58 pm

I doubt if there's anything to worry about, but a pressure gauge connected to the fuel supply line to see what happens after the engine is switched off is the way to check.

Post Tue Oct 30, 2012 7:12 am

A few guy on e36coupe has said the same Brian thats its nothing to worry about.

Does anyone else on here get it from there m52 with m50 inlet using m52 injector rail?

Post Tue Oct 30, 2012 9:57 pm

Mine does this. Does it with both m50 inlet and m52 inlet.

After shutting car off, you can hear the icv buzzing and hissing for a few seconds. Then after a few seconds it does one big hiss and a click, then goes silent.

Post Tue Oct 30, 2012 10:02 pm

See it as proof you have no air leaks

Post Tue Oct 30, 2012 10:13 pm

Why does it prove that there are no air leaks?

Post Tue Oct 30, 2012 10:19 pm

It always sounds to me like its hissing through the manifold, I keep meaning to turn off then open the throttle to see if it still does it

Post Tue Oct 30, 2012 10:27 pm

redcar wrote:Mine does this. Does it with both m50 inlet and m52 inlet.

After shutting car off, you can hear the icv buzzing and hissing for a few seconds. Then after a few seconds it does one big hiss and a click, then goes silent.

mine did is, before i cleaned the IVC. Now after 6 months+ its sweet

Post Tue Oct 30, 2012 11:04 pm

My m50 does this too no grief from it .

Post Wed Oct 31, 2012 7:00 am

DanThe wrote:See it as proof you have no air leaks

Funny you should say that Dan.
I was changing the clutch last week and had to remove the inlet to get to the top bellhousing bolt.

When i had the inlet off i noticed the hose from the icv to the tb boot was split.

I replaced it with a new on when putting back together and thats when i noticed the hissing.

Thanks for the replies lads