90 brake problems, pulling and locking

[steakneggs]

Since it is an intermittant problem, I would say it's the ABS portion of the Teeves. I would disconnect it and drive it carefully and try to duplicate the problem before I would start throwing money at it. You don't need ABS anyway. It's for incompetents. Put a piece of tape over the light. Or let it shine to remind you not to tailgate. Steak

[nic walker]

hmmmmmm....

[ncgirl05]

Found the TSB:

Technical Service Bulletin # Date: 940101
Intermittent Pull Under Hard Braking (Vehicles W/ABS)
Group Ref.: Brakes
Bulletin No.: 315004
Date: January, 1994
SUBJECT:
INTERMITTENT PULL WITH A HARD BRAKE APPLY DURING NON-ABS STOP ON ABS EQUIPPED
VEHICLES (REPLACE ABS VALVE BLOCK/PRESSURE MODULATOR VALVE)
MODELS:
1986-90 BUICK ELECTRA
1986-91 BUICK LESABRE
1988-90 BUICK RIVIERA, REATTA1991 BUICK PARK AVENUE
1986-91 CADILLAC DEVILLE, FLEETWOOD
1988-90 CADILLAC ELDORADO, SEVILLE
1986-91 OLDSMOBILE NINETY-EIGHT, EIGHTY-EIGHT
1988-90 OLDSMOBILE TORONADO, TROFEO
1986-91 PONTIAC BONNEVILLE
EQUIPPED WITH ANTILOCK BRAKES
THIS BULLETIN IS BEING REVISED TO ADD THE 1991 MODEL YEAR FOR "C" AND "H" VEHICLES



INCLUDING PART AND WARRANTY INFORMATION. PREVIOUS DIVISIONAL PUBLICATION NUMBERS
WERE:
DIVISION BULLETIN NUMBER
BUICK 90-5-17
CADILLAC T-93-134
GM OF CANADA 315004R
OLDSMOBILE 90-T-213
PONTIAC 90-5-19
Some owners may comment on intermittent pull with a hard brake apply, but without ABS
activation. The intermittent pull can be either to the left or right and only occurs
with hard non-ABS stops.
This condition may be due to a base brake condition, loose suspension component, or
the Antilock Brake System. When working on a vehicle with this condition, use the
following procedure:
1. Inspect the base brake system. Check for loose or binding calipers, damaged
rotors, or restricted brake lines. Refer to Section 5 of the applicable Service
Information Manual for complete inspection and repair procedures.
2. Inspect the suspension system. Check for loose control arms, damaged struts, or
bushings. Refer to Section 3 of the applicable Service Information Manual for
complete inspection and repair procedures.
3. If nothing is found during the above inspections, replace the AntiLock brake
system valve block, (pressure modulator valve for 1991 models). Follow the
procedure in the appropriate Service Information Manual.
1986-87 C/H Models Valve Block .....P./.N 25530880
1988-90 C/H Models Valve Block .....P./.N 25533639
1988-90 E/K Models Valve Block .....P./.N 1646523
1991 C/H Models Pressure Modulator Valve P/N 25559182


We did steps 1 and 2 above and found nothing, which was frustrating. Looks like the valve block according to this.

[steakneggs]

I converted mine to a Riviera unit for less than half of what that Rube Goldberg valve block costs. Steak

[nic walker]

PROPORTIONING VALVE ASSEMBLY was the word/s I was at loss for....below is a portion of a post by Drake referring to the PVA.

Proportioning Valve (s) [Re: nic walker]
Drake
Member

Registered: 02/19/08
Posts: 186
Loc: Oswego, Illinois

"Nic, you are absolutely correct about the proportioning valve assembly ( valve block assembly ). It is actually a main part of the Teves unit itself."

[steakneggs]

The proportioning valve is not part of the Teves. The proportioning valve is located near the left rear wheel. It regulates the front/rear bias during normal braking and wouldn't have anything to do with severe pulling. That would have to be related to a bias between the two front wheels. If some restriction or frozen caliper has been ruled out, it would have to be in the valve block, which might be functioning in some partial ABS mode or something. You can buy a used Teves for less than $100 that you can get the valve block off of. Steak

[Mc_Reatta]

Think I would do a complete brake fluid flush first and see what shows up. I had a front rubber brake line that was disintegrating from the inside that was giving me intermittent problems. If you see lots of black or rust colored particles in the drained fluid you have probably found your problem. I would buy a complete rebuild Teves off the post on eBay rather than pay that much just for a valve block Assy.

[DAVES89]

I saw Jim Finn today at my favorite u-pull yard. He grabbed two of them. One is sure to work. Try him.

[steakneggs]

I had a follow-up to my last post that has disappeared reminding you to depressurize the system before you pull the valve block off the Teves. Steak

[ncgirl05]

oooohhh - Thanks! We're going to make the switch today - glad I was reading threads this morning! [img]<>/shocked.gif[/img]

[ncgirl05]

Originally Posted By: nic walker

PROPORTIONING VALVE ASSEMBLY was the word/s I was at loss for

I think the proper term is PROPORTIONER VALVE ASSEMBLIES. I am looking through the service manual now and just saw this - these proportioner valve assemblies go into the master cylinder.

Funny enough, I had to order a PROPORTIONING valve for my other '89. If you happened to see my other thread about brake fluid being 'all gone' - this was the reason for THAT car.

Geesh - you know, if these cars had "normal" brakes we probably almost wouldn't need a forum! [img]<>/grin.gif[/img]

[ncgirl05]

Originally Posted By: DAVES89

I saw Jim Finn today at my favorite u-pull yard. He grabbed two of them. One is sure to work. Try him.

Okay, I was just reading the service manual and it instructs one to take off the hydraulic unit before taking off the valve block... if Jim grabbed 2 of them, then I'm assuming he did NOT take off the hydraulic unit and just took off the 3 retaining nuts to remove the valve block. Correct? Is the manual making it more difficult than it should be? [img]<>/confused.gif[/img]

[steakneggs]

I've never removed the valve block, but I don't see why you would need to remove the Teves which IS SOMETHING YOU DON'T WANT TO DO. Don't lose the O rings. Steak

[bobwhite]

When I had this problem, it would pull and lockup once every month or so. I never knew when it would happen, so I had to try to be ready all the time, what a pain. I tried the easiest recommended solution first, I replaced the brake fluid and did a flush of the braking system as per the instructions for a Reatta. That was about ten years ago. I haven't had that problem since, and I change the fluid and have a flush done every year or 18 months. Other than replacing the accumulator once, and replacing the brake pads, I have not had any more braking problems. Someday I would like to do the brake upgrade with bigger wheels and rotors.

[ncgirl05]

We performed the 'operation' today and after a test drive filled with quick stops I can report SUCCESS. [img]<>/laugh.gif[/img]

However, my ABS light, which has been on for some time, is STILL on. [img]<>/frown.gif[/img] But right now I'm just happy about the straight braking.

[nic walker]

Y E S ! [img]<>/smile.gif[/img]

[steakneggs]

You need to see if the ABS is working. Wait until it rains and find a safe area and try to lock the brakes. Have somebody standing out there to watch. Just not in front. Steak

[robl30166]

Hey guys i stumbled acros your post here while i was doing a abs problem search on my 90 olds toronado trofeo. let me give you a little back ground on my issue.

I have a 1990 Oldsmobile Toronado Trofeo. I got in it the other day and started it and put it in gear. I noticed the brake pedal was hard as a rock, and my abs and brake stayed on in the instrument cluster. It usually goes off after a few seconds after starting the car. This car has a on board diagnostics system . I ran threw it and it didn’t show any codes. I pulled out the shop manual and it also didn’t show anything about what I am experiencing. I pulled that would disable the abs also the abs module in the trunk still nothing the pedal was still solid. Under the hood by the master cylinder were 4 connectors I unplugged them one at a time to see if that would do something and yet again nothing.
So my next though was lets see if I can bleed the pressure off so I did the front 2 brakes first. As soon as I opened the valve they went to the floor. Ok so I went to the back brakes did the same nothing came out any air or brake fluid. My first thought was the paportion valve is bad or stuck. By this time I have been working on this for about 4 or so hrs and I stopped where I was so I could do some reading up on it later. The car sat there for about 2 hrs then I had to move it to put my other car in the car port I got in and
Put it in gear and the brakes we back to normal. Abs brake lights went off and all drove the car around the block a few times everything seems fine. I didn’t get under the car and see if I was getting fluid to the back calipers but the stopping power seemed even. So I just assumed it was working fine? Now the car has been sitting a week I haven’t drove it
Kind of in fear of not really knowing what happened to cause that. Couldn’t have been a stuck valve in the back?

Update. I since drove the car the abs lights and the e brake lights don’t stay on after starting the car. So I took out the car and wanted to see how the brakes felt , and they
Felt fine so I wanted to get in back and bleed the back breaks since the last time when I wasn’t getting any fluid. This time I had my why get in and pump the brakes and then I opened the valve I got plenty of break fuilding to come out but the pedal would not go to the floor. The front ones when right to the floor when I bled the front. Anyone ever heard of this or had it happen to them. Any suggestions are appreciate. Here is my email if you would like to drop me aline with possible causes or things I can check ROBL3870@VERIZON.NET

Thanks Rob

[CL_Reatta]

Hi, email sent.... should start a new thread though.

[EDBS0]

Hi and welcome to the forum. Do the brale test here.

[Barney Eaton]

Back to the original problem. Car pulling to the right or left when the brakes are applied.

Lets say it pulls to the right..... that is because the right side is working and the left is not.

This can be multiple problems and you just need to address them one at a time.

You could start by verifying you are getting fluid to the left side.

If you are getting fluid then you need to look at the caliper/piston

If no fluid is getting to the caliper then you check the rubber hose, and the ABS valve body....it could be sticking, somehow getting a false signal that shuts off the flow of fluid, there is even the possibility that some foreign material is blocking the line.

[steakneggs]

To bleed the rears, to answer an earlier question, you turn the key on and gently apply the brake while an assistant opens the bleeders. Nothing will come out without the key on no matter how hard you push because the rear brakes are disabled when the key is off. As far as the pulling problem, if both front wheels bleed when the valves are open, then the hoses aren't restricted. I've never seen a caliper that wouldn't operate under pressure. Sometimes they won't return if they're rusty. It must be in the valve block which I don't believe is repairable except possibly swapping solenoids (don't know). But earlier in this thread someone swapped a valve block with a used one. Steak

[Squire Tom]

funny that i ran across this post. i had an 1988 olds touring sedan. bought it used with about 40k.in about 92 or 93.
my antilocks caused the REAR end to actually " jump " to the left under moderate to hard braking . dealer couldn't relate to it until the head wrench took it for a ride with me . ended up replacing some valve bodies etc in the antilock system . no charge to me . there must have been some GM bulletin regarding the brakes as they knew right away what was amiss and never even mentioned any charges.
i do not know what braking system was in the 1988 Touring Sedan , but i wouldnt guess is was different for the TS . really miss those 16 way seats though.

[Barney Eaton]

The Olds touring sedan and the Pontiac SSEI both came standard with the same Teves ABS unit as our cars.

[Squire Tom]

from ncgirl05 post listing models affected by the brake problems. how many of these affected vehicles have interchangeable parts with reatta/riviera?