bimmerjunkie

Hello,

Vehicle is a 99 4runner Limited 4WD with 152K on the clock.

I've replaced 4 wheel cylinders in the last 9 months (left rear wheel). First two were cheap Autozone parts; the fist lasted six weeks and the second lasted 7 months or so.

I normally don't buy cheap parts, so after the 2nd Autozone part failed I sourced a cylinder from Autohausaz. I've bought parts from them for 5-6 years with no problem. The first part from Autohausaz started leaking on the first drive. I contacted Autohausaz and had the part replaced. I installed the second Autohausaz wheel cylinder yesterday. Again, on the first drive after the install, I have brake fluid leaking from the wheel.

This time I pulled the dust boots back on the wheel cylinder before removal. I was expecting to see brake fluid, but they were dry.

The brake shoes and springs I have installed are from Autozone. I don't think that would have a bearing on the problem, but....

Now I'm totally confused. If brake fluid is leaking from the wheel area, it HAS to be coming from the wheel cylinder, right? I don't know where else it could be coming from.

I've got to be missing something basic here.... I can't believe that I've had 4 bad cylinders in 9 months.

On the up side, I can replace a cylinder in about 15 minutes now. :-)

Any ideas?

Thanks,

Mark

Shibby!

You are correct. Wheel cylinder pot seals, or bleeder bolt seal but that's out the back of the wheel.

Are you using the correct DOT3 brake fluid?

82wingnut

are you postitive it is brake fluid? there is the chance your axle seal is leaking, check both the brake fluid reservoir and diff for fluid level

tunnelmotor99

Is fluid leaking from the cylinder boots or from the bleeder nipple or brake line connection? I would avoid cheapo wheel cylinders, I've seen them missing the internal springs and even the pistons before!

bimmerjunkie

Thanks all....

I'm using Valvoline synthetic Dot 3 & 4 brake fluid. Should be OK, right?

The leak is internal to the brake drum. It is not leaking from the bleeder nipple or brake line connection. If it was I would expect to see brake fluid on the backside of the wheel.

It appears to be brake fluid. Of course it's not clean because of the brake material, but it has the same consistency.

I will check the diff level. But if it's an axle seal would that leak inside the drum?

Thanks again for the responses.

J2F42C

I have to ask why you replaced the original cylinders? Preventive maintenance?

Are the brakes soft/mushy?

How is the passenger rear look/operate?

bimmerjunkie

I replaced the original left rear cylinder because there was a pool of brake fluid at the base of the tire. The first time I replaced the cylinder I had no leaks for about 6 weeks. Then it leaked again. As I said in the original post, I used cheap parts, so I suspected the part was bad. I replaced the cylinder a second time with another Autozone replacement and it lasted 7 months.

The parts I sourced from Autohausaz are not cheap. The wheel cylinder is about $55, which is near the toyota dealer price.

If the cylinder was leaking I would suspect brake fluid in the dust boots, but they were dry. Maybe it is the axle seal. I still have to check the diff level. However, the leaking fluid doesn't seem thick enough for diff gear oil. We'll see.

bimmerjunkie

To answer your other questions:

1) The brakes have felt fine after replacing the wheel cylinder. The pedal has never been really firm as compared to my BMW, for example.

2) I'm not sure what you are asking about the "passenger rear look/operate".

I should add the bleeding the rear wheel cylinders has not been easy. I use a Motive pressure bleeder. I've had to bleed them multiple times and, even then, I'm not sure I've got 100% of the air out. There is no problem bleeding the front calipers.

DRCOFFEE

The author is an ass but maybe this thread will give you some insight. Its not brake fluid.

Axle leaking

You can do a quick check by removing the ABS sensor out of the axle housing. If its wet looking like honey, it's the axle.

bimmerjunkie

DRCOFFEE,

That's exactly what it looks like. Dang, I would have bet good money that it was brake fluid. In hindsight, I think the smell should have given it away.

Thanks a million for that link. I guess I will be replacing the axle seal.

Mark

DRCOFFEE

Plan on doing both. it'll save you in the end. If you plan to do the work yourself, read this thread too. Its actually not too bad if you have a good machine shop to install the spacer correctly.

https://www.yotatech.com/forums/f2/r...ebuild-226134/

http://www.ncttora.com/fsm/1996/SIL/...a/ras/comp.pdf

Page 3 is something you should take to the machine shop. If I had to do it again, I'd have him install the inner spacer inboard by 2mm. 124.2mm

Factory Service Manual

bimmerjunkie

Anyone know a good machine shop in the Fort Worth, TX area?