Brake vacuum leak.

2003 basic(very) purchased new white truck. Experiencing quick loss of brake vacuum when turning the engine off. I want to check the vacuum check valve that’s mounted on the round black vacuum reservoir(?) below and behind the brake fluid reservoir. I tried pulling and twisting it to see if it would come out but didn’t want to overdo it until I confirm it’s supposed to be removed that way. Is that correct? Engine runs fine and truck runs great otherwise.

 

Just what causes you to think your losing vacuum??

Experiencing a constant High idle?

That piece should pop right out but plastic parts get brittle with age and break very easy be careful!

 

The "round black vacuum reservoir" is the Brake Booster. I suggest you find yourself a digital copy of the factory service manual. Google search "1st gen tacoma FSM" - should be able to find the zip file pretty easily. Rock Auto also has a cd for purchase with the exact same zip on it.

The FSM has specific troubleshooting instructions for the brake booster. The brake boosters have been discontinued, so aftermarket reman is going to be the only option. They are a pain to remove as the master cylinder is in the way. Be weary of the master cylinder and letting air into the brake system, especially if you have ABS.

 

Thanks for letting me know it does pull out Bivouac. The engine does not idle high. Just runs normally. The reason I want to check the check valve is because once I shut the engine off it become almost immediately the brake pedal becomes very hard to press down. Restart the engine and all is well again. It may be the brake booster but I’m starting with the cheap stuff.

 

Andy, thanks for that info. Gonna do that search for the manual. Should be very helpful in the future as well. I don’t have ABS or any options except AC and Cruise control. Oh, and a radio. 76000 miles.

 

Probably your booster itself, I had mine replaced by a local shop and had the exact same issue when I got it back. I drove around like it for awhile as they said it was the best they could do. I had a local Toyota expert replace my ac system for me and he said the booster was bad, I told him to go ahead and fix it he refused as I hadn't to long had it replaced. I carried it back to original shop they put another booster in under warranty and it feels great I no longer have to stand on the peddle to stop the truck. Do you hear air whooshing in the cad by the pedal when you press it normally. I know with mine you could turn the truck off and let it sit overnight and the next day it was stiff again.

 

Thanks for your reply griff. Guess I’ll find out. I’m going to start checking prices for remanufactured units.

 

if you can get the check valve out you can try to suck through the pipe the hose goes on I believe if it lets you suck through then it should allow the engine to pull a vacuum through the booster. Then when you blow back through it the valve should close and not air through it I believe that's the correct way to check it. Also when you have the hose off the check valve crank the engine up and see if you can air sucking through it that will tell you if the hose is blocked I doubt it is. The booster itself isn't hard to do just working under the dash part sucks. I did the first one myself but ended up with a defective one and after trying everything with it I carried it to local shop who also installed a defective booster but they got it straight recently. If you do it yourself you should be able to get enough movement with the brake lines to remove the master cylinder without disconnecting anything. I ended up during the original troubleshooting replacing my master cylinder too. Make sure you get a measurement of the clevis on the booster before you remove the clevis.

Youtube is your friend on this one there are a few videos on it.

 

Thanks again Griff. I got it out and it seems fine. Ive ordered a remanufactured booster from Amazon. There are a bunch of new ones from second party companies that were much cheaper. I decided on the rebuilt OEM. Spent the afternoon watching YouTube so if I can bend by 77 year old body to get under the dash I think I won’t have major problems. May be an example of “famous last words”.

 

it's not to bad I took out the panel under steering wheel and it made it easier I was approaching 50 when I did mine the first time

 

I've noticed lately that when I go to start the truck, hard brake pedal. Was never like that before (that I can recall). Once started, all is well.

Check my signature below, last line/link.

 

Those are my exact symptoms as well. My check valve was good so replacing the brake booster. $155 on Amazon for OEM remanufactured.

 

Following.. I’m experiencing similar symptoms.
Except my 02 PreRunner has a high pitched, hella annoying whine. Almost like a dog whistle, coming from behind the dash underneath the windshield.

 

That's almost certainly the brake booster.

 

Last night I noticed, while I was driving, that it only makes the high-pitched whine whenever my foot is NOT on brake pedal. Kinda sus yeah?
Ok good to know, & have a second opinion Mahalo!