Find a vacuum leak...

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I break things.
Aug 14, 2006
Oceanside, CA
When I drive my brakes work fine, but after a night sitting, I have a hard pedal until.the vacuum pump builds it up again...

On a gasser, carb cleaner was the tool for finding leaks. Where do I start here? 1981 2B BJ44.

I did just disconnect the vacuum hoses and connected them together with a piece of hose (at the frame rail). This was due to a tranny/transfer swap with a fully mech shift transfer. Was this not.correct?
Maybe plug them off closer to the source. Or maybe plug them on their own don't loop the hose...

Worth a try.

Could messing with the system when unhooking it have caused an issue?

Could messing with the system when unhooking it have caused an issue?


Check valves eventually go bad/get contaminated. They are essentially the same as a PCV valve. Disconnecting anything on a 20 year old truck can cause problems. Vacuum hose and plastic fittings can crack easily. Vacuum reservoirs can rust out.

The worst case scenario would be the vacuum pump being shot. But seeing that you have good vacuum, that is not your issue. You just have a small leak somewhere in the system. It could even be the booster diaphragm has developed a small leak. Usually that is found after you have had the outer master seal allowing brake fluid to leak back into the diaphragm. Like I said before, best to use a vacuum pump gauge to help localize where the leak is. It shouldn't be too hard to find.

A vacuum pump gauge kit looks like this

and runs between $40-100 depending on attachments. Some kits also allow you to do vacuum bleeding of brakes and clutch hydraulics.

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