vacuum leak

[free]

I am trying to hunt down a small vacuum leak (06/88 325ic). My vacuum gauge bounces a little and is about 12 -13 on the gauge. Can't remember the units of measure, but Bentley says it should be 15-22 and steady. Its not really vibrating, so I don't think it is valve guides. Head was redone about 20k miles ago by PO anyway.

When pull on the vac line going to the brake booster, I can hear air hiss. But the car has been off for hours now. Could this be my vacuum leak? Sounds like the air is coming from the fitting to the booster...

Also, does anyone know the part number for the funny looking hose that goes from the bottom of the throttle body to the check valve that is connected to the charcoal canister? the check valve also has an electrical connector plugged into it. I have looked all over on realoem and can't find it, and took the part into my local import auto parts store with no luck.

Any other ideas for a small vac leak? dipstick and oil filler cap look good, dipstick tube seems tight. intake manifold gaskets are good. Intake boot is new and good and tight on MAF. Hose from valve cover is good. Have sprayed carb cleaner all over the darn place. Orings on injectors look good and injectors are about 20k miles (although they were very dirty except for tips).

Anyway, thank you for the help.

[Emre]

When pull on the vac line going to the brake booster, I can hear air hiss. But the car has been off for hours now. Could this be my vacuum leak? Sounds like the air is coming from the fitting to the booster...

The brake booster is indeed a common source for a hidden vacuum leak.

[free]

The brake booster is indeed a common source for a hidden vacuum leak.

Whats the fix? Do I really have to replace the whole thing?

[dashboardmonkey]

Whats the fix? Do I really have to replace the whole thing?

Yup, replace it.

[free]

PelicanParts wants $580 for a booster. I found a new gasket for $5 for the connector that the vacuum line goes on. Assuming I can get the connector out without screwing something up I am going to replace that first. If I can't change the gasket, I am going to cover it in JB Weld and cross my fingers.

[free]

Replaced the gasket and tore apart everything from the head to the airbox. Think I have cleaned it up as well as I can. I still get vac fluctuation at idle, but can't tell if the vac is fluctuating and causing a miss, or the miss is causing the idle/vac fluctuation.

Could it be valve guide seals?

[vr2jetta]

Also, does anyone know the part number for the funny looking hose that goes from the bottom of the throttle body to the check valve that is connected to the charcoal canister? the check valve also has an electrical connector plugged into it.

I am having cold start issues and slightly rough idle problems, could this be deleted all together? I have no emissions testing where I live and was wondering if this will mess something up.....CEL, ECU problems?

[vr2jetta]

I am having cold start issues and slightly rough idle problems, could this be deleted all together? I have no emissions testing where I live and was wondering if this will mess something up.....CEL, ECU problems?

Nevermind, just did some searching and reading.....imagine that, and found it is better to just replace the lines going to it and keep it around. Dont want the car smelling like gas and have a loss of fuel economy.