RTH: Brake booster leaking — Can it be rebuilt?

[Eicca]

I ran a search but didn’t see any attempts to fix leaking brake boosters. Everyone just replaced theirs. At $2k for a new one, that’s out of the question right now. And the only used ones on eBay are crap.

So it’s bad enough that I’ve got a puddle of fluid on the fender under the hood and the fluid level went from middle to “min” in about two days. The underside is all wet looking and caked in accumulated dirt.

Is there a common place that these leak from, like where the reservoir meets the master cylinder? Is it even possible to get the seals for this?

I’m 300 miles from home and a shop right now so my only option is to fill it up and drive it back. The brakes themselves operate fine. No noises from the booster pump or anything. All the pads and rotors were replaced last summer.

Advice greatly appreciated.

 

[2001LC]

Typically you'll find fluid in DS foot well from master plunger seal leak. Could be where reservoir fit into grommets to master. Either condition is rebuildable.

If pump or accumulate leaking you'd need to replace those, which are sold separately.

Test: Key off, pump peddle 40 times, fill to max line, turn key to on (don't need to start), time how long booster pump runs. You're looking for 30 to 40 seconds. If more than 40 seconds book states to bleed system. More than 40 seconds indicate system not reaching desired pressure. If system is bleed properly (no air) and takes longer than 40 seconds, then leak is probably not at the reservoir or it's grommets, which make the condition very dangerous, so do not drive.

By advised; Driving with a leak is very dangerous. You could lose hydraulic pressure and have zero brakes.

 

[Eicca]

Typically you'll find fluid in DS foot well from master plunger seal leak. Could be where reservoir fit into grommets to master. Either condition is rebuildable.

If pump or accumulate leaking you'd need to replace those, which are sold separately.

Test: Key off, pump peddle 40 times, fill to max line, tune key to on (don't need to start), time how long booster pump runs. You're looking for 30 to 40 seconds. If more than 40 seconds book states to bleed system. More than 40 seconds indicate system not reaching desired pressure. If system is bleed properly (no air) and takes longer than 40 seconds, then leak is probably not at the reservoir or it's grommets, which make the condition very dangerous, so do not drive.

By advised; Driving with a leak is very dangerous. You could lose hydraulic pressure and have zero brakes.

I’ll run those tests. I don’t really have any other way to get it home and fixed than to drive it so here’s hoping it’s not critical.

 

[Eicca]

Ok. So when all the pressure is relieved the fluid level returns to the midddle. I timed the pump and it ran for 38 total seconds with one pause somewhere in there.

No sign of fluid on the firewall under the dash.

 

[Eicca]

It looks like the fluid is coming from the motor area. The master cylinder itself seems pretty dry.

Is there a complete seal kit I can get for this?

 

[2001LC]

IDK if you can buy a all in one kit. You can buy individually "seals". Punch in your VIN at this site: www.partsouq.com

38 sec is good, pause is normal. This indicates you're holding pressure. Leak may be at reservoir grommet or O-ring at bottom of accumulator our a couple spots that come to mind. If you can hold pressure you'll have brakes.

 

[Eicca]

Ok, so the fact that it holds pressure fine makes me believe that the leak is not on the pressure side of the system. If it were the accumulator O-ring, it would lose pressure and probably leak quickly, yeah?

I’m suspecting the hose that feeds the fluid from the reservoir down to the pump, or the reservoir grommets.

 

[2001LC]

Probably but I'm really not sure as there may be a check valve downstream. Cleaning and watching for reappearance may be best courses of action. Leak in reservoir is one more to consider. Any chance it was overfilled which may have damaged reservoir or grommets.
Some random picture;

 

[Eicca]

Well I filled the brake fluid, drive 300 miles home, cleaned the unit up real good and a week later it hasn’t lost any fluid at all.

I’m suspicious.

 

[BReynolds]

IDK if you can buy a all in one kit. You can buy individually "seals". Punch in your VIN at this site: www.partsouq.com

38 sec is good, pause is normal. This indicates you're holding pressure. Leak may be at reservoir grommet or O-ring at bottom of accumulator our a couple spots that come to mind. If you can hold pressure you'll have brakes.

I need one repaired that has a leak. It appears that the leak is between the black module housing and aluminum body. Do you rebuild these?

 

[2001LC]

I need one repaired that has a leak. It appears that the leak is between the black module housing and aluminum body. Do you rebuild these?

Leak may be above, from grommets or from overfilling.

If you're correct where leak is from, it's not repairable with a seal. Best, replace the booster assembly whole master (the whole deal).

 

[BReynolds]

Leak may be above, from grommets or from overfilling.

If you're correct where leak is from, it's not repairable with a seal. Best, replace the booster assembly whole master (the whole deal).

View attachment 3365449

Okay. Thanks

 

[BReynolds]

Leak may be above, from grommets or from overfilling.

If you're correct where leak is from, it's not repairable with a seal. Best, replace the booster assembly whole master (the whole deal).

View attachment 3365449

Do have a recommendation on where to purchase one?

 

[SteveH]

Do have a recommendation on where to purchase one?

Your local Toyota dealer, or one that will do it at cost + $25 or so. Various threads on this, and my signature has a link that'll get in the neighborhood.

 

[2001LC]

Do have a recommendation on where to purchase one?

Toyota Sale on now July 6-7th, with free shipping. The parts guy Eric, at autoparts.toyotaofdecatur.com. Is best bet, to reduce chance of shipping damage. As he opens the factory box an repacks it. The only one I've ever found that does this. If damaged in shipping, I don't except. I just make claim for replacement.

 

[2001LC]

BTW: I use www.partsouq.com to get part numbers, using my VIN# (very import, use your VIN number). It's much better than many Toyota web portals.

 

[BReynolds]

Toyota Sale on now July 6-7th, with free shipping. The parts guy Eric, at autoparts.toyotaofdecatur.com. Is best bet, to reduce chance of shipping damage. As he opens the factory box an repacks it. The only one I've ever found that does this. If damaged in shipping, I don't except. I just make claim for replacement.

THANK YOU!!!

 

[BReynolds]

Toyota Sale on now July 6-7th, with free shipping. The parts guy Eric, at autoparts.toyotaofdecatur.com. Is best bet, to reduce chance of shipping damage. As he opens the factory box an repacks it. The only one I've ever found that does this. If damaged in shipping, I don't except. I just make claim for replacement.

I just ordered over 2k worth of parts and referenced you to Eric. Definitely saved some money going that route.
Thanks again!

 

[BReynolds]

Leak may be above, from grommets or from overfilling.

If you're correct where leak is from, it's not repairable with a seal. Best, replace the booster assembly whole master (the whole deal).

View attachment 3365449

I just noticed that the booster reservoir seems to be loose and rocks back and forth. Maybe the grommets are leaking from too much play? Wasn't sure if its supposed to have play in it..