Brake Problem in the Cold

[ski92]

92 4x4 5-speed

While sking this last weekend I sudden developed very low to almost no braking pressure. It had been cold the whole weekend, highs in the teens. Braking had been fine, peddle would move a couple of inches for god solid braking.

Truck had been sitting in mid teens for hours and I let it warm-up for a couple of min before leaving. When leaving from the parking I recall no problems. When exiting the lot I had to brake suddenly and very hard to avoid hitting another car that was sliding by in the snow pack, out of control.

As I can remember, immediatly I started having braking problems. The peddle went nearly to the floor untill I got a very minimal amount of braking.

By using the gears and going slow I was able to continue sking for a couple of days, getting a very minimal braking, but there was some braking when the peddle was about 1-1/2 inches from the floor

Other observations:

-No fluid loss from master cylinder
-Pumping peddle would get a bit more braking power
-When running at speed for a while it would seem to get a little more brawithke peddle but it would go away quickly

I topped-up th master cylinder(all the way to top of resivoir) and headed out for the 7 hour drive back to San Diego. Made it back with "no problem".

One thing I notice, as I got back to SD I had more braking ability( a little less brake travel.

I did the test for the power brake booster in the manuel and it was ok.

I think it's the master cyl, blew a seal.

Any other suggestions?

Thanks in Advance

 

[wood1]

I'd check to be very sure you haven't popped a line somewhere. Check that the booster has a good vacuum connection too. If that checks out you might be correct about the MC leaking internally. Either way, stop driving it until you fix it!

Welcome to the site and Happy New Year!

 

[ski92]

LATEST UPDATE:

Went to take it to mechanic for MC change...AND... everything was fine! Peddle pressure fine, back to where it was before. Mechanic suggested the proportioning valve.

Thanks for the advice W1: There is no lose of fluid at the MC resivior. Checking the vacume lines seems good idea.(cruise control works fine).

Any suggestions on the proportioning valve.

 

[ski92]

Is the proportioning valve the mechanic mentioned the same as the RABS valve I came across when searching the site?

 

[wood1]

Hmmm, I think I have heard guys say they solved issues when they bypassed the RABS module. I just don't know enough about ABS systems to say.I did pull the fuse onmy 4WABS... it sucks...

 

[Roadrunner777]

Cold temps hardened the booster vacuum line causing leak? Replace the hose, for what, $5? I'd flush the brake fluid, usually overdue anyway.

 

[ski92]

Cold temps hardened the booster vacuum line causing leak? Replace the hose, for what, $5? I'd flush the brake fluid, usually overdue anyway.

When the problem first occured I checked the lines and they seem fine, good condition, on tight. Also, did power booster check,: w/ motor off, pumped peddle, it was hard and stayed in position. Any other checks for vacume problem?

 

[F150hybred]

k, you say you were skiing... did you give any thought that maybe the rear drums were packed with snow? It does happen and gives symptoms that you're describing.

 

[ski92]

k, you say you were skiing... did you give any thought that maybe the rear drums were packed with snow? It does happen and gives symptoms that you're describing.

How exactly would that happen? There wasn't a lot of falling snow, it was windy at times, and it's not happened in any other ski seasons. Although, this trip I did not use the emerg brake when parking for long periods because previously it had seemed lock-up and it took some engine power to brake the emerg brake loose.

Right now my plan is flush brake system, replace the vacume hose(I assume this is the approx 3/4" rubber hose going into the power booster). And if I'm flushing the brake sys. ,maybe replace MC since it's only $40-50 more and flushing sys is most time consuming part to MC change.

Any other suggestions?

 

[F150hybred]

You would be amazed where blowing snow can get into. Nothing better than getting to your vehicle after a blizzard and looking under the hood to NOT see an engine. Brakes are the same way. Snow will whirl and whip snow in such a fashion that it will get in there. This same effect can happen by just driving along the hiway.
Now... you say you were having issues with the park brake previously and it "seemed lock-up and it took some engine power to brake the emerg brake loose". That might be another avenue to explore.

 

[wood1]

Happened to me a few weeks ago after the ex had been sitting for a week. We got a good storm, strong winds and I forgot to try the brakes before the hill... Was going for the ditch until the brakes finally pumped up. Weird but it happens once in a great while.

 

[F150hybred]

Happened to me a few weeks ago after the ex had been sitting for a week. We got a good storm, strong winds and I forgot to try the brakes before the hill... Was going for the ditch until the brakes finally pumped up. Weird but it happens once in a great while.

Must be a Canadian thing, eh?

 

[wood1]

Don't know. Temps were about -30 C with quite a wind... I thought it was probably snow packed in the brakes, mentioned it to a mechanic buddy who agreed.

 

[ski92]

Don't know. Temps were about -30 C with quite a wind... I thought it was probably snow packed in the brakes, mentioned it to a mechanic buddy who agreed.

I guess I don't quite understand how packed snow in the rear brakes causes the peddle to go down so far before any braking. Also, it seemed (it was a little hard to tell on the snow) that what braking I had could lock-up the front brakes. Still tryign to work this out before I go back sking.

 

[$$exploder$$]

Did u check your abs valve on the driver
frame rail

 

[wood1]

Good question. I don't get it either...

edit:

I'm guessing that I was pressing pretty hard on the pedal when I wasn't getting any breaking action, and my perception was incorrect.

 

[ski92]

Did u check your abs valve on the driver
frame rail

I've looked at it. Looks pretty clean on the outside. This is a CA car and the underside looks pretty good in general.

How do you go about checking the abs valve?

 

[Corik]

How long has it been since you flushed your brake fluid? It attracts water and maybe its too old and freezing up the lines or something??
to test the brakes pump them five times and turn the engine on. Your pedal should drop slightly, this indicates good brake booster action.

 

[ski92]

How long has it been since you flushed your brake fluid? It attracts water and maybe its too old and freezing up the lines or something??
to test the brakes pump them five times and turn the engine on. Your pedal should drop slightly, this indicates good brake booster action.

I'm aware of the booster check, does that give you info on the abs valve? Is there a sprcific test for the abs valve?

 

[ski92]

After driivng around and comparing to my reg street car, the peddle does go down over half way and a couple pumps of the peddle gets the peddle a little higher. I'm still unsure of base cause. Although the cold may have contributed to the problem, I do't think it was the root of the problem. Seems to be either MC or abs module, though no leaks from either. Any further thoughts.