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Weird brake problems

2731 Views 10 Replies 4 Participants Last post by  Paul M
Okay here goes 1989 suburban 2wd

The complete brake system has been rebuilt. The only items that have not been replaced has been the power brake booster & the hard lines - EVERYTHING ELSE HAS BEEN REPLACED
system has been bled numerous times. I have good solid flow when I blead the lines. I have nice firm pedal.

PROBLEM: On a wet road the right front wheel will lock up & I go sliding into oblivian..... This ONLY happens on a WET road, on dry pavement you can stomp on the pedal & this thing will stop straight & true with no pull

I have been told that I need to have the lines power flushed & power bled - that there is a varnish build up in the hard lines & when the tempature changes some of the varnish comes off of the walls of the hard lines & gets into the master cylinder or some other place - causing this problem.

It has gotten to a point that when it rains I don't drive it, it sits in the driveway -


please e-mail me at [email protected]

In all my years of working on cars I have never had this problem, I mean this Suburban has new rotors, new calipers, new master cylinder, new front & rear brake hoses, new proportioning valve, new pads, new drums, new brake springs, new wheel cylinders, new shoes, new shocks, & new tires............................


Thanks for all of your help

J. Gary Bodnar

[email protected]
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Did you bench bleed the master cylinder? Which direction does it slide in?
There is a weird problem I have experienced where the flex lines have failed internally. Causing like a check valve. Fluid runs in but drains back slow causing the scenario your talking about.(Serious pull to one side) Just another option...Good luck.

I thought about that which is why I repaced everything including the brake hoses, I am wondering this & maybe you might know who to ask..........

Since the right front is the one that locks up on a wet road & since I have been told by numerous people that the brakes on this Suburban are set up in an "X" pattern ->R/F - L/R - L/F/ - R/R that Maybe - Just Maybe I should replace the Hard line running to the L/F? Maybe there is a restriction in the line? & that when I am on dry pavement it is not noticable - but on wet pavement since it is slick & because of the weight of the vehicle the r/f locks up ????????????????????

Does this sound viable?

Like I said I am @ a loss here & I am just trying to make some kind of sense out of this way out wacked out anomolie that I have...............

Very Respectfully,

J. Gary Bodnar
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The right front will lock up & I slide to the right - the steering wheel will turn to the right & Awaaaay I go! I always aim for the curb when it happens..................

My only other option is to go very slooooow & constantly pump the brakes hoping that the pressure stays the same? so I stop evenly - the shop that did the work bench bled, gravity bled, this bled ect. to it. The doggone thing will shoot fluid out like crazy when we bleed it - & it will be fine for awhile & it comes back...............yikes what a mess
Your right you did say everything. My mistake. The brakes do control in an X pattern. I think hard lines are cheap to do on an older truck??? Provided the proportioning valve has definately been done. I don't see what would cause that other than suspension in RF is weak (I.E. shocks springs etc) causing it to nose dive a bit.

Oh Yeah, its been replaced, because before I replaced it I was getting very little fluid to the rear wheels - had to get the proportioning valve from a guy in north carolina, as for some freaking reason the proportioning valve for the 89 suburban has been discontinued

So this company in north carolina manufactures them now. stil pretty pricey, but I was right there helping the mechanic replace it (handed tools & pumped the brakes when bleeding them out)

So I will replace the L/F hard line & fittings & see how that works - If this one does not work I don't know what else to do, don't want to get rid of the truck as it is the last car my father I worked on right before he died.......... so the truck has allot of sentimental value to me, (plus it looks pretty good for its age) - I just got to figure this brake problem out......................

Very Respectfully,

J. Gary Bodnar
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As crazy as it might sound, it sounds like a new part that you put on might be faulty as well. From what your telling me you've put one part on at a time trying to solve? But try the hard line first. Then you might have to start at ground zero, maybe another mechanic? Brake specialist in town?

No I did a complete overhaul @ one time - $500± in parts & $250 in labor

I discovered the problem shortly after I bought the truck (on a wet road)

Had many long discussions with my Father about it, Started buying all the parts to overhaul the brake system @ one time instead of piece mealing it - plus I thought @ the time it was bad calipers (week ones) & due to the milage 150,000± plus the retired pastor who I bought it from use to tow a 31 foot camper with it, I would replace everything in it with new stuff & start fresh (exersize the old demons) but this problem has come back again so in my thinking it must be the hard line going to the left front wheel?

as for other shops & speacilists - no one knows - they say it is not possible for this to happen. I have heard sludge in the lines - bad hoses - I need to rebuild the system again - bad tires- etc. etc, Everyone wants me to spend thousands of dollars leaving them the truck while they tear it all down (while charging 95 bucks an hour) for them to
investigate the problem - I don't think so - I don't have a big pile of money to throw away randomly.

I do have right now A gentleman who is a co-host of the auto repair show on our local talk radio station & who is co-owner with the host of the show in a very successful & a very good reputable shop trying to find out the problem - I had sent them an e-mail last week & he called me today, told me that he was stumped, puzzled, & very curious as to what the problem is & that he was going to get with gm & post it on some forrum that has over 150,00 repair shop owners on it & see if he can't find out what the problem is,
& that he will call me back & keep me updated on what he finds out.

He does not want to get into tearing things apart & running up a bill with diagnostics & stuff till he knows what direction to go. Thank God - I hope he finds out something.............

Very Respectfully,

J. Gary Bodnar
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Well thats super if he'll help you out. Shy of all of us coming down to help you personally LOL. Good luck keep us posted. If you find something good I will "sticky tread" for future reference.

Thanks Jamie
It seems you replaced the brake system except for a few brake lines. My 89 Silverado has ABS. Since you mentioned that it does it only when it is wet, this may affect wheel speed during braking and maybe the ABS is messed up. There was another post that indicated the ABS could be electrically disconnected. Try this out when it is wet outside and see if the wheel still locks up.
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