Ricu_air

Hello everyone.
I have some trouble with my truck brakes. Cleaning the truck I noticed that the rear drum, driver side was dirty because of an oil leak.
I opened the drum and there was oil everywhere. I tried to apply the brake and see if there was a leak somewhere but it was hard to find. I think is the wheel cylinder because today when I cleaned with the brake cleaner I saw few drops of oil coming from the right side of the wheel cylinder. My first doubt was that the oil was gear fluid but the seal between the axle and the brake seems to be fine: that area is clean, no oil. Is it possible that the gear fluid is leaking from somewhere else? Is there only one seal for the gear fluid?
The other thing is that the brake light in the dash is on plus the oil in the reservoir was low when i bought the truck.
Attached 2 photos to try to clear a bit more the situation.
Thanks for your help.

scope103

Are you sure it's gear oil? If you have a leaking wheel cylinder, it will sling all over brake housing. If the brake fluid is dirty to begin with, once you mix it with the dirt in the brake it could look like oil.

Since it's almost certain that the wheel cylinder needs replacement, you could do that, put it back together, and check the axle-seal again after 100 miles or so. A wheel cylinder is $4-$15 at Rockauto.

wyoming9

iTrader: (1)

Brake fluid and gear oil smell nothing alike!!

From your picture your wheel cylinder is leaking and should be replaced.

Brakes what you do to one side should be done to both!!

Ricu_air

I checked the exploded wiew of the rear axle. There is only one seal, which is on the axle to keep the gear oil into the axle, right? So if that one is leaking I should find that tipe of oil in the brake drum. Correct?
Is it possible that a seal on the wheel cylinder is leaking and the brake fluid is coming from there?
BTW that wheel cylinder was not working properly as well

scope103

Doesn't your photograph show fluid under the rubber boot on the wheel cylinder? Didn't you actually SEE a leak? It should be dry under the boot; your wheel cylinder is leaking. (You can buy seal kits for wheel cylinders, but at $4-$15 to buy one already re-manufactured, I don't see how anyone could afford to rebuild one on their own.)

osv

oil in the reservoir?? there is brake fluid and there is gear oil, but there is no such thing as brake oil

so are you talking about the reservoir for brake fluid being low?

even if there is rear end gear oil leaking past the axle seal, it shouldn't be able to get inside the slave cylinder boot, so your pic of fluid under the seal sure looks like a bad slave cylinder.

i would get factory aisin slave cylinders, if you can find 'em, not remanufactured stuff from your local flaps; do both of 'em, not just one... i like to drain the old brake fluid out of the bleeder screw first, so that none of it gets into the new slave cylinders... start with the furthest slave cylinder first.

scope103

The OEM wheel cylinders are about $60 each online; probably closer to $100 in your local dealership. While both of your wheel cylinders are the same age, they are not a maintenance item, and have no particular life-span. So I've been okay with replacing just the bad one, and I'm happy with remanufactured items. I'm not real cheap, but I'm willing to keep the extra $170. It's your choice; these are brakes, and no one will criticize you for spending a little more.

You WILL have to replace the shoes on both sides; those really do need to be replaced in pairs, and the one soaked in brake fluid is no good anymore. So the LABOR to replace both wheel cylinders is the same.

If you really are worried about dirt in the brake fluid, don't stop with the rears. Replace all of the brake fluid. More work, but not much, and brake fluid is not expensive.

Terrys87

iTrader: (1)

I flush my lines with Marvel Mystery Oil and an air hose. Lots of gunky stuff comes out. Flush from both ends. Gets it cleaner then just pumping the brake pedal. If you get a Slave Cylinder from Napa or Orielly, double check to see if it is an exact replacement.

Toyota switched slave cylinders in those years and you can get the wrong part for your year. The pistons in the slave cylinder is different lengths in those years.

My experience.
Parts Stores Cylinder. The piston would not stay in.


The one on the right is what I should of had all along. The one on the left is the parts store piston.

osv

"Aisin transfers brake sales to ADVICS ...The ADVICS Group was established globally in July, 2001, when Aisin, Denso Corp., Sumitomo Electric Industries and Toyota Motor Corp. joined together to create a company to develop and sell automotive brake systems. Aisin has since produced and supplied components for ADVICS’ brake system development." http://www.autoserviceprofessional.c...ales-to-ADVICS

advics wheel cylinders are $14.58 at rockauto, see the aisin name cast into the body of the wheel cylinder: http://www.rockauto.com/catalog/more...id=495&jpid=14

they don't appear to be remanufactured... those are for the later model '87 brake system.

i think that at some point the ifs rear ends got larger diameter rear brake drums, is 1987 the year that it happened? definitely don't want to get the wrong part, i've done that with these wheel cylinders.

Ricu_air

Finally got the job done. It was the BRAKE FLUID leaking from the wheel cylinder. Now everything is working fine. Tomorrow it s a big day: new engine.
Thanks everyone!

Terrys87

iTrader: (1)

I am thinking 87 is the year it happened, the smaller piston will work for an 87. 85/86 has the longer piston and if I recall right the assembly is slightly larger as well. At worked to bleed the brakes and for several miles and then the piston just popped out. It is the correct part for the correct year but it is something I really dive into when doing a rear brake on the 84-88 trucks now. I do alot of comparison between the old and new parts. Any more when swapping parts I just make it a habit of comparing the old and new replacement part.

wyoming9

iTrader: (1)

Does the Marvel Mystery Oil Mix with Brake fluid with no problems ????

Maybe you really need to flush things with clean brake fluid??.

Terrys87

iTrader: (1)

I run alot of air thru the lines afterwards. My way of thinking is for it to help break up the rust in the lines. I could try using clean brake fluid, but would it help clean out the lines? Something I never really thought of.

You do bring up a good point and something that I will start doing after flushing the lines with Marvel Mystery Oil to flush behind the MM Oil with clean brake fluid and then fill the system like you normally would. Just thought that when I stopped getting oil out of the lines that it was just a little residue left and not much would hurt.