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86 Pickup Brake Master Cylinder: Which manufacturer?!
Hello everyone!
So, I don't post often to any forums or threads, so forgive any ignorance.
I have an 86 Pickup Custom Cab my father bought new. He passed away about 4 years ago and I have it now, and can never ever get rid of it. I currently drive it 4 days a week for work, and its doing great but has some issues. Most recently, and seriously I suppose, is the brakes seem really mushy or soft, and it has almost NO stopping power. I absolutely must use gears if I have any hope of stopping the truck. Usually I can get away with leaving myself plenty of following distance or time to slow down, but if something happens I have no control over (like wildlife or other drivers cutting me off) I will NOT be able to stop in time. I checked the brake pads and i have like 1/4" of material still there, so that can't be the problem, rotors look great too. I checked the reservoir and it was almost at max, so I don't believe I'm losing any fluid to leaking? Anyways, someone mentioned that the MC could be allowing fluid to flow back into the reservoir, lowering or eliminating any PSI build up in the lines so.... no stopping. I want to replace the MC but I notice that there are many manufacturers: Aisin, ACDelco, Wagner, Cardone, Centric, Beck/Arnley, Advics, Raybestos, etc...
After reading a dizzying amount of opinions I'm left needing your help: What manufacturer do I buy? Some are only $40, but some say they don't last. Others are much more expensive, and some say they are overpriced and I will be ok with the cheaper ones. HELP ME PLEASE!!!
I just want my truck to stop and not kill anybody.
Thank you for your time and and info you can give me,
~Polo Quick photo I found.
...He passed away about 4 years ago and I have it now, and can never ever get rid of it.
~Polo
Welcome to Yotatech! I am sorry about your loss but happy about your gaining a reliable, capable truck. Never ever get rid of it. I have never heard anyone say he was happy he disposed of his 22RE Truck.
I suggest you take your time thoroughly troubleshooting to make sure which part is defective (and share what you find out).
If you must buy a new MC, I would recommend Aisin. It makes OEM for Toyota. I have not replaced my brake MC but have my clutch MC. I went cheap from O'Reilly but after a few months it started to leak. I took it back to O'Reilly under warranty. Fortunately the gentleman who helped me was able to find an AISIN replacement for me at no additional cost! Had been working great for around 6 years.
Before you buy anything check your MC by pumping it a few times and then holding the peddle while the engine is running. If the peddle slowly looses pressure then you need a new MC. If it holds pressure then the problem is probably somewhere else. You can also have someone watching the reservoir as you pump it and watch for bubbles or fluid swirling around.
If the MC is still good then flush and bleed the system. Check your LPBV (Load Proportioning Brake Valve) under the spare tire. If it's not functioning correctly you'll never get the system to bleed correctly.
If you need a new MC then Aisin. Hands down.
1) It's a prized possession you're not going to get rid of so buy the best you can.
2) It's a life safety issue. So buy the best you can.
I didn't see where you stated whether this is an 22RE or a 22R (Carburetor). Check your brake booster vacuum pressure also.
Do not cheap out on a brake master cylinder. I had issues with cheaper master cylinders failing even before I installed them in my truck. The ones I got would not even bench bleed properly.
I agree with the above. If you need a new brake master cylinder, get an Aisin / Advics master cylinder. Advics is the brake division of Aisin.
For my 2 Wheel Drive Truck, the Aisin / Advics master cylinder was the exact same as the Genuine Toyota version, except that they ground down the word "TOYOTA" on the side so they can sell them aftermarket.
Firstly, THANK YOU SO MUCH FOR RESPONDING SO FAST!
Y'all are amazing, tell your family I said so.
I had my wife pump the brakes while I watched the reservoir, no bubbles or movement of any kind. I tried pumping the brakes as you said to see if that built up pressure and then slowly lost it, and it does lose pressure and drops to the floor. I got my neighbor to try it out and he said he experiences the same thing, it starts strong but drops to the floor soft after a second or two. So, looks like the MC?
I went ahead and bled out all the old nasty brake fluid to brand new DOT3 stuff, which I've never done before so that was cool. I did not see any air in the lines coming out before the new clear liquid, so that doesn't seem to be contributing to the problem. Tested again and the problem did not improve at all.
The truck stops, its not like there are NO brakes at all; it just stops very slowly, and the peddle is mush. My neighbor suggested going to a pick and pull and grabbing a used MC off a vehicle but....... As you mentioned, life and death? I think I'll just do it right the first time.
Any other tips - keep 'em coming!
The truck has several other little issues (some not so little) that I plan on fixing in the future, so I'll be sure to come back and pick your brains some more!
I'll let you know how it goes when I replace the MC.
Thank you again!!
Also check to make sure the vacuum power assist booster is working. Try applying brakes with the engine off. Do it several times to bleed any vacuum out of the booster. Then, with your foot on the pedal, start the engine. The pedal should drop a significant amount as the booster applies more force. If it doesn't, you have a defective booster.
Lack of vacuum assist will make your brakes feel pretty ineffective.
Ok, finally got the part in the mail!
So I bench bled the new MC, installed it, bled the lines again. This time the brakes felt a lot stronger! But when driving there seems to be only a small improvement in stopping ability, maybe like (just guessing here) 10-20% better.
I tried testing the vacuum as RJR mentioned; pumped up the pressure with the engine off, started the engine and, yes, I did feel the pedal drop.
When I test the brakes on my private road (don't worry I'm not driving down the highway I notice that they respond better if I pump them vigorously a few times then slam on the brake. But if I just hammer down the brake w/o pumping, the braking doesn't seem to be that much better.
Any further suggestions?
I really appreciate all the info you have provided thus far! Thank you again for your time!
Have you checked the brake calipers/wheel cylinders on each wheel? The pistons could be rusted only allowing one or two of them to actually apply pressure. Check for uneven pad/shoe wear as one side may have more wear than the other. That goes for each side of the caliper as well as each end of the pad. Check your rear drum brakes and make sure the shoes are adjusted properly and the auto-adjuster isn't rusted. The majority of your stopping power is your front brakes.
Sorry its been a while since my last post.
After replacing the Master Cylinder I've been driving the truck. It is braking a LOT better now. The only thing I notice is that when I first brake, there is almost no pressure and it's very mushy. But after the initial press, the next several presses are very firm and the brakes work great. After driving for a minute or so, the pressure is gone again and I need to do a pump before the pressure is hard again. What might this indicate? Air in the lines? Or could it indicate that the booster is not holding?
Did you bleed the brakes in the correct order?
Essentially, it's longest line to shortest...
RR, LR, RF, LF, LPSV
I understand that air in a longer line can migrate to a shorter line, so doing them in order is important. Also, air trapped in the lpsv can make the back brakes mushy. Really messes up the whole system. Also, if the LPSV is bad, it can act like this.
I had an 87 4runner that did the same thing you mention:initial press on the pedal went to the floor, and then the brakes worked fine until moving again and then the same thing would happen. Ended up being a bad front wheel bearing. Jack up your truck and make sure your front wheels don't have excess play.
Ok, so I will try bleeding them again. Just as an FYI I did try my best to bleed them in the correct order the previous times, Rear Right then Rear Left then Front Right and finally Front Left. However, I did not bleed the LPSV. So... woops. Haha. I'll make sure to do that this time!
I had no idea the bearings could cause a problem like that (but again, what DO I know? haha I'm not a mechanic!). However, funny enough, while I've been having this particular problem with the brakes, my front right bearing died, so I replaced both sides. It did not change the braking issue at all.
Again, THANK YOU for your responses and ideas, as well as patience with someone who clearly is a novice at this.
~Mark
11-22-2019, 07:53 PM
