vacuum leak after turning engine off

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Jul 1, 2003 | 01:44 PM

kwd1

Thread Starter

Melting Slicks

Joined: Apr 2002

Posts: 2,947

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From: North Aurora Il

vacuum leak after turning engine off

Hi,
I noticed a hissing sound after turning the engine off. It is coming from near the
firewall on the passenger side. I haven't been able to localize it. It only happens if the heater or ac was running before turning off engine.
I also don't know if it is a vaccum leak or something outgassing.
It does it with the engine cold and warm.

any ideas?
thanks
Ken

Jul 1, 2003 | 01:46 PM

0ski_dwn_it

Former Vendor

Joined: Jun 2001

Posts: 7,204

Likes: 6

From: St Marys PA

Re: vacuum leak after turning engine off (kwd1)

9:1 its your power brake booster....Mine used to do that. Inspect it for cracks. Or a leaky hose fitting. Its the plastic piece right behing your master cylinder.

Hope its not cracked....How are your brakes? Harder to apply than normal?

Jul 1, 2003 | 02:57 PM

kwd1

Thread Starter

Melting Slicks

Joined: Apr 2002

Posts: 2,947

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From: North Aurora Il

Re: vacuum leak after turning engine off (ski_dwn_it)

The hissing is coming from passenger side, isn't the booster on the right?

I thinks its coming from the heater/cooling system assembly near the passenger side firewall
on the outside of engine bay.

Jul 1, 2003 | 08:34 PM

SunCr

Le Mans Master

Joined: Dec 2000

Posts: 7,839

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From: San Diego, Ca

Re: vacuum leak after turning engine off (kwd1)

It's probably just the a/c. Once off, pressure in the high & low side equalize making the noise you describe.

Jul 1, 2003 | 08:47 PM

CentralCoaster

Team Owner

Joined: May 2002

Posts: 24,337

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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed

Re: vacuum leak after turning engine off (kwd1)

Mine does this too. I believe it's a/c heating or coolant related. :lurk:

Jul 1, 2003 | 10:19 PM

Lone Ranger

Le Mans Master

Joined: Feb 2002

Posts: 7,858

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Re: vacuum leak after turning engine off (SunCr)

Quote:

It's probably just the a/c. Once off, pressure in the high & low side equalize making the noise you describe.

:withstupid: :yesnod:

Jul 1, 2003 | 11:28 PM

Kens86

Instructor

Joined: Jun 2003

Posts: 187

Likes: 0

From: Orange Park Fl

Re: vacuum leak after turning engine off (kwd1)

It is possibly the AC heater control unit. If it is a manual unit it could be the slide or vacuum line connnections that go to it. Check to see that air flow goes to the vent, defog, and heater correctly when you move the slide to those positons Also, when you move it slowly from one positon to another do you hear it hiss? If it is only from AC to OFF you are probably ok.