Brake booster vacuum leak

[lostmarbles]

I guess it is possible that the vacuum leak could be just this seal here leaking........ and if so, perhaps just some fresh silicone grease on the rod my fix it.



.............Just an idea

 

[Jan-78FJ40]

Ok, so here's where I have to make it clear, as if it were not already, that I am dealing with a novel situation for me. In fact, a good 85% of the working mechanicals on this truck are foreign to me at this point in my wrenching career.

I do not know if my fluid levels drop at all as I suggest, the reservoir levels are not droping over time (no fluid loss, thus I must presume no leak between master and booster--no leak into booster or to anywhere). But, as I stated, there was definitely a brake fluid leak between the booster and master at some point in the past, based on the corrosion on the lower half of the booster's shell, but apparently repaired.

After shutting down, I attempt to locate the hissing sound (the vacuum leak) and to the best of my ability, with me crawling up into the engine bay (hey, I am small enough to do that), it sounds like the leak is inside the booster. Presumably a torn diaphragm, right?


My plan of action, and Mel Lowe agrees, is just replace the booster and see if that stops the leak. If so, great, done. If not, no harm other than loss of maybe 30 minutes or so.

No problem, we all have started at zero at some point.
As you said, if there is no drop in fluid levels you can eliminate the fluid leaks at this time.

Yes, changing the booster will fix the problem (if it resides in the booster), but calculate more than 30 minutes for that task. A lot more. You need to undo the brake pedal connections (very good if you are small) to the inside of the booster, then unbolt the 4 12 mm nuts on the inside of the firewall.
Then (or before) undo the 4 12 mm bolts that hold the brake master to the booster. At this point you might have to undo the brakelines from the master or not, depends on how far you can wiggle the thing to the side without kinking the brake lines. If you have to undo the brakelines you have to bleed the whole shebang in the end too. If not, things are much easier.
Then reverse the operation, while cursing about the little room you have under the dash for all of this.
cheers,
J

 

[Tofudebeest]

No problem, we all have started at zero at some point.
As you said, if there is no drop in fluid levels you can eliminate the fluid leaks at this time.

Yes, changing the booster will fix the problem (if it resides in the booster), but calculate more than 30 minutes for that task. A lot more. You need to undo the brake pedal connections (very good if you are small) to the inside of the booster, then unbolt the 4 12 mm nuts on the inside of the firewall.
Then (or before) undo the 4 12 mm bolts that hold the brake master to the booster. At this point you might have to undo the brakelines from the master or not, depends on how far you can wiggle the thing to the side without kinking the brake lines. If you have to undo the brakelines you have to bleed the whole shebang in the end too. If not, things are much easier.
Then reverse the operation, while cursing about the little room you have under the dash for all of this.
cheers,
J

While I respectfully acknowledge the general concept that "it alwasy takes longer than you think it will", this is truly a one banana job (provided the brake lines do not need to be bled).
Further, you underestimate my diminutive stature. I can curl up under the dash with the seat in full forward position, if I had to. I'm 5'4" and a buck 47. Tell ya what, when I do this job, I'll time it. I'll be honest about how long it takes. Mel Lowe (if he's present for when I do this job) will vouch for me. We're replacing my springs and have about 4 hours, so I'm not sure we'll get to it. I'll PB Blaster the hell out of my suspension tomorrow night and Saturday for our Sunday wrenching...

 

[TLC Norway]

How did this end, Tofu? I'm into learning all about the fawIng brakes now... got a leak or something... not getting any pedal. Wierd stuff, but now i am sure i have all the vacuum i need, so there has to be an internal fluid leak somewhere, right? WHERE? i have no fluid loss, and a fresh fluid. This started during offroad, and now has gotten worse, and i dont dare drive the 3HR drive tomorrow unless this is fixed...

 

[amaurer]

How did this end, Tofu?

Booster just needed a good whack:

https://forum.ih8mud.com/chit-chat-section/408488-tofu-rolled.html

 

[TLC Norway]

I know, but i still wanted the story of how the fix ended.

On a note to what i just wrote two posts up:
Should i guess that the MC is failing?
DAMN, then i need to redneck it together somehow, tomorrow!
Trailfixes for a MC?

 

[canucksafari]

You can change that oring seal on the booster. I know that mine is leaking. But it only leaks when it is very hot outside. Sounds like a sick cow. It never gets very hot for too long here, so I live with it.