brake booster vacuum check valve... where is it????

[daeron]

Okay, in my efforts to get my engine to run worth half a toot on a trombone, I am wanting to inspect the vacuum supply to the brake booster. I wonder "Maybe there is a vacuum leak there, I should check the check valve."

 

Now, I should have noticed this one of the times I seafoamed the car; I always use the brake booster vacuum line.. but I can NOT for the LIFE of me find a check valve!!! Is it built into the manifold, or the booster somehow? I haven't tried disconnecting the line at the booster end and trying to see if I can blow into the manifold yet.. but I have never seen a check valve that didnt stick out and say "HEY, LOOK AT ME, I'M THE CHECK VALVE!!" so I am somewhat puzzled.

 

Half an hour searching only turned up one other thread where a guy could not, for the life of him, find his check valve.. he asked several times but nowhere was it unambiguously answered; he seemed to think it had somehow been deleted by a PO and I am beginning to wonder if I am in the same boat.

 

I may well just go to the JY soon and eyeball a loyale there.. I'm thinking about snagging a FPR to swap onto my car to see if THAT helps any.

[Reveeen]

The brake booster check valve's function is to hold vacuum in the brake booster (to provide safe braking) in the event that braking is required if engine vacuum somehow dissappears.

The valve will either be in-line, or a part of the plastic fitting where the vacuum line attatches to the brake booster.

If the brake booster still assists brake application after the engine is shut off the check valve is functioning as it should. If there is no retention of vacuum in the booster after shut down then either the check valve is faulty, or the booster has a vacuum leak.

A functioning, or not, check valve should not affect engine running, only a leaking booster will. The "usual" test for loss of vacuum through the booster is to squeeze the vacuum hose with a pair of pliers (if you can't hear it), closely watching a vacuum guage.

[daeron]

Thanks a million reveen, I am having a 100% meltdown of my cognitive function today because I have quite frankly, been beating my brains against this car trying to figure it out.

 

if you are curious what I have been going through, just check almost any thread I have started in this forum in the last two months... but theres no need, if you dont want.

 

the short version is, I am no longer able to hold any confidence that I am not missing something obvious.. in ANY situation involving this bloody thing. hoepfully the FPR i just picked up at the JY will fix my problem; I was simply alarmed at NOT seeing a check valve. I guess if the thing is built into the booster, that would explain it.. I pulled the hose off of the manifold after I made the post, and blew through it (no) and sucked through it (yes) so the check valve is there and functioning....