92 Chevy S-10 brakes

92 Chevy S-10 Blazer 4 X 4, 4.3 W engine 3.42 gear 157,667 miles

I might add, about 8,000 miles back I put new pads on the front brakes, rear brakes have never been replace, but both times I put new pads on front I checked them, they still have quite a bit of lining left on them.

I've got some brake troubles on my Blazer. I went to town to pick up medicine for my dog Saturday morning and my brake pedal goes nearly to the floor. I make it back home just fine ad today I called the parts store where I always buy my parts for the man is very good at telling you what to check.

My 1st thought was, being as I was not losing no brake fluid, and had found no leaks, that the master cylinder was by passing, I know in the old days that would happen from time to time. My parts man ask, do you have any brake lights shining. The answer to that was no. he said to check my back brakes, they probably need adjusting up.

This morning when I would 1st put my foot on the brake pedal, I would have a good pedal, but it would slowly go to the floor, but it still had enough brakes that with my Blazer in Drive, I could push the gas pedal down a bit and the brakes were holding it. back.

So I jack up the left rear and pull the tire and drum, the brake was quite loose. After being sure all look correct, no leaks, put the drum back on and adjust up the brake, did the same on the right rear.

Before I let the jack down on the right rear, I checked to see what the brake pedal would do. I pushed down, had a good pedal and it did not go to the floor. I really thought I had the problem solved.

But after letting the jack down and heading down my long driveway the first time I hit my brakes hard they held right good, had a good pedal. Them I went backwards and hit them, this time the brake pedal goes slowly to the floor.

Both my brake light and the ABS light are now shinning. Master cylinder had plenty of brake fluid.

I can still put it in Drive, bump the accelerator pedal just lightly, holding the brake pedal down, even thought it goes to the bottom the brakes still seem to hold.

If this was per ABS junk, I would know what to do, but this modern day stuff is greek to me.

Any ideas? And thanks for any help y'all might be able to give me.

Thought I would add this for what its worth, never been used off road and never been in a wreck, I and the wife put all these miles on it.

4W or 2W ABS brakes.
A hard full pedal is lose of vacuum to brake booster or bad booster.

Pedal leaking/seeping down is fluid leakage or master cylinder bypassing.

Recheck all lines and calipers and rear cylinders for leakage.
Is self adjusters on rear working good?

Have brakes been bleed?

Does rear brakes still apply good?

Thanks much for your reply

From what I understand, from Auto Zone site, 92's had 4 wheel ABS brakes. Mine does have the 4WAL Brake Pressure Modulator Valve which is shown on the auto zone page listed below.

<<"The four wheel anti-lock brake system was first used on these vehicles on the 1991 4-door models. The system became standard equipment on 1992 and later models including the Typhoon. The 1991-92 systems are unique in that they used 4 wheel speed sensors (one located at each wheel) while the other systems use the Vehicle Speed Sensor (VSS) signal for rear wheel speed.">>

http://www.autozone.com/az/cds/en_us/0900823d/80/12/b9/37/0900823d8012b937/repairInfoPages.htm

No leaks, all the brake fluid that has been added has been because of normal brake wear, as they wear the brake system will hold just a bit more brake fluid.

I don't suppose from the time this 92 S-10 Blazer was brand new that the back brakes has ever adjusted their self up properly, for surely if they had they would be worn out from the 157,000 plus miles on it. But at present time they are adjusted up, this is the 3rd time they've been adjusted, the other times was when replacing the front brake pads twice, always checked the back brakes & while doing so adjust them up. they appear to be maybe half worn down.

Friday when this happened the master cylinder was completely full and no lights. Lights came on only after I checked and adjusted the back brakes them hit my brakes quite hard while driving down my long drive way.

No, I have not bled the brakes, for the master cylinder is full and has never been low enough to get air.

Just now I went out to my Blazer, before cranking the engine I had a full brake pedal, when I cranked it, it fell to the floor, but see the Auto Zone says that is normal, if I understand it properly.


"<<Test for system operation as follows:
Pump the brake pedal (with engine off) until the supply vacuum is entirely gone.

Put a light, steady pressure on the pedal.

Start the engine, and operate it at idle. If the system is operating, the brake pedal should fall toward the floor if constant pressure is maintained on the pedal.">>

From my reading from Auto Zone web-site seems there is more than 1 thing that can cause this problem. I'm going to think a bit about this, I may call the Chevrolet place and get them to check it out, they're the only ones who have worked on it besides my self. It would be so nice is they weren't so complicated, but those uncomplicated days for our automobiles seem to be gone forever.

Pedel to floor is not normal.
You have a problem there.

No, the brake pedal slowly going to the floor is not normal at all, since I bought it in 92 it had never done such a thing. But when they get old such things do happen.

Seems my Brake Pressure Modulator Valve is having trouble, the bleed valve on the drivers side of it will not bleed.

Mechanic at the Chevy shop is going to try and come up with a tool to work on it, says you can hone the valve inside of it, I going back up there Monday to see what he comes up with.

Don't know much about this valve, but don't think you can get them no more, may have to by pass it if we can't get it going. But besides that I understand they were quite expensive.

Anyone who has had trouble with Modulator Valve I would appreciate letting me know what you did about it.

I had trouble with mine when I bought the truck and had to replace it for inspection - I went through the flowchart for the code and found that the BPMV was toast.

But I went to a pick-n-pull and got a new-looking one from a '94 for $50 (crossing my fingers the whole time). Put it in and took it to a dealership to have it bled and have had no trouble since.

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'93 Bravada vin W

I had trouble with mine when I bought the truck and had to replace it for inspection - I went through the flowchart for the code and found that the BPMV was toast.

But I went to a pick-n-pull and got a new-looking one from a '94 for $50 (crossing my fingers the whole time). Put it in and took it to a dealership to have it bled and have had no trouble since.

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'93 Bravada vin W

Thanks for telling me about your experience. Hoping I will have your success.

Friday I carried my Blazer to the Chevy house were I bought it new in 92. I might add I bought a new Jeep Grand Cherokee from them in 2001. The 1st thought my master cylinder was out, they replace it with a rebuild one, problem stayed. I took it back up to them this morning and they called me saying the part for it cost $1115.00.

I asked them it they would by-pass it, of course the answer was no becasues of liability reasons. I told them I could not go that, that was really more than my old Blazer was worth, that I would have to try to by-pass it and I just could not go that prices.

When I went to pick up my Blazer, no charge. Pretty good, rebuilt master cylinder, the 1st one it has had and no charge.

I went to my favorite parts store which I been dealing with since I was 5 years of age when my dad had a station them later on I ran the station a for several years. He talked me into getting a used one from a salvage yard, called the salvage yard, 40 mile trip to the salvage yard and 40 mile trip back home with a $60.00 used one and if it don’t work bring it back and we will give you another one, if we happened not to have another one your money back.

I’ve got it installed, will find out tomorrow if all is well or not when my grandson comes up and we bleed the brakes. Of course I’m hoping for the best.

Good luck!

Just so you know, if any air got into the BPMV, you will not be able to bleed it yourself. You need the Chevy scan tool to properly bleed it (that's why I took it to the dealership).

Thanks to each person who replied to me, I do appreciator your comments.

Now all seems to be working well. so it seems its better to spend $60,00 at the salvage yard than $1500.00 at the Chevy place for the ABS valve or commonly called the BPMV.

This valve is not difficult to change out and it was not that hard to get the air out of the brake system after replacing. And the BPMV can make your brake pedal do the same thing as it will when the master cylinder goes bad and bypasses inside.

I got the air out of the BPMV valve by bleeding the BPMV at the incoming lines, them bleeding each of the wheel cylinders starting with the left rear.

I now have a firm brake pedal and it no longer slowly goes to the floor.

I hope all of you will have a Happy 2008 Thanksgiving and will form many precious memories in your minds to fondly look back on for many years to come.

Cool! I'm glad a $60 part took care of your $1200 problem.

Until today my brakes worked great, them this afternoon the wife and I were headed to the back woods and it did the very same thing once again. Worked great for about 3 months.

Now I'm thinking about what to do next, maybe try another used one.