Hey guys, I've lurked here for a while and have gotten so much valuable info! I'm hoping that someone can help rescue me on this one.

I drive a 94 4Runner 3.0L 6cyl. Anyhow, today on the drive home the brakes didn't seem to have any power. The pedal didn't hit the floor or get mushy or anything, so I know it likely is not the Master Cylinder. We're checking out the vacuum hoses and such, but it looks like there is only one large one coming off of the brake booster - according the the Chilton's I have. Also, when I press the brake the idle drops. I know that indicates a vacuum leak, but where and how should I check? Any hints or tips...please. Oh - and yes I did check the fluid level and it was just fine.

Thank you for any input!

Edit: Removed the vacuum line from the booster and plugged it, when I pressed the brakes the idle didn't drop but still had brakes that are hard as heck to push...can I bet this is the booster? If so, is it a difficult fix?

 

pull the vacuum line off the booster & plug it.step on the brake.if the idle does not drop you've got a bad booster.good luck

 

Thank you! Is it hard to fix?

 

it can be a pain but if you have any mechanical aptitude you can do it.just take your time

 

The worst part sounds like bleeding out the brake system...I hope that's a good guess. Doesn't look hard judging by the Chilton's, but then again it usually seems easy til somethings unscrewed.

 

Bleeding it out is easy. Just bench bleed the master then have someone pump the brakes while you go right rear, left rear, right front, left front. Takes about 15 minutes to bleed the braking system.

 

i thought it was left front, right rear, right front, left rear? but yeah bleeding the brakes isnt anything to worry about, its really easy

 

Well breaks are something to worry about. But they aren't that hard to work on.

 

Where do you expect I might run into problems replacing the booster? I just can't shell out the $700 for some shop to do it! Highway robbery. Seems not too tough, but we're not exactly mechanically gifted. I want to learn more, but I sure don't want to get in over my head. I've done easy things before, brakes are a little intimidating, I guess. I sooo appreciate the input.

 

try it. most likely it'll come out fine. just test it some after you finish. lol. if you really get nervous and your not sure you want to do it or can do it, send it to a mech. even if u screw it up a good mech can fix it. just takes $$$

 

You DO NOT have to bleed the brakes for a simply booster replacement.
You never have to crack open the lines...







Fred

 

On mine, you have to crack the brake lines to get the master cylinder off the booster, before you can pull the booster. We had them both out a couple of weekends ago for troubleshooting. We will be pulling them again tomorrow for replacement, so I will attempt to get the booster out without opening the hydraulics, but I can't imagine any way to pull that off...

 

Had no problem on my '95, 3.0..





Fred

 

replacing the booster is not hard but it is a pain in the ar$e main thing is getting under the dash and steering column to the 4 nuts that hold it in place best to have a few socket extensions also have a 12 mm deep well if I remember correctly.


heres a link to a link for the shop manual https://www.yotatech.com/forums/f123/links-factory-service-manuals-part-numbers-102344/

 

Thank you so much! I feel much better about this attack now.

 

also go to a junk yard first and see if you can get a booster cheap first I have yet to find a good deal on a new one.

I helped a friend do his brakes lucky for him I had a booster for a 4cylinder
any way replaced it and nothing then replaced the master and still nothing then we ended replacing the front calipers guess what still had a problem then replaced the rear cylinders and bingo the rears where full of crap. so 300$ later in parts we found the problem.

I would start by bleeding your system.

I now bleed my brakes once a year might be over kill but the fluid comes out black and gritty every change.