After 45 minutes of driving my rear passenger brakes started smoking?

DESTINATION_UNKNOWN

MEMBER
1997 GMC SIERRA
5.7L
V8
4WD
AUTOMATIC
260,000 MILES

Just replaced the master brake cylinder and booster 4 days ago. Have driven about 6-800 miles since and all has been fine. This morning after about 45 minutes of driving my rear passenger tire started smoking a decent amount. Is it the wheel cylinder? I replaced the booster because both rear cylinders were not engaging while depressing the brake pedal.

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
42,913 POSTS

It sounds like the brake system is being held on due to the brake master not returning fully. I would jack the rear of the vehicle up and see if you can spin the rear tires freely, if they don't loosen the brake master cylinder mounting bolts about 2 turns to see if the rear wheels start spinning, this way you know it is a master or the push rod in the booster needs to be adjusted inward to give the master more play and so it can return fully. Also, you can see if the plunger inside the master is fully returned in the master housing. If this doesn't help and the rear tires are locked you will need to force the drum off to check the shoe adjustment, also I wanted to ask if you did both sides at the same time is there a change you got the self-adjusters mixed upside to side? This will cause the problem as well. Please let me know what you find, Ken

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Sunday, February 12th, 2023 AT 9:44 AM

DESTINATION_UNKNOWN

MEMBER
10 POSTS

The tires spin freely. You said if I did both sides, are asking if I changed the brake shoe? If so, no I didn't. Since the first message I put new wheel cylinders on. I'm not sure how to tell if the plunger in the housing is fully returned or not and also this booster does not have an adjustable rod. So i'm not sure how to make sure it's at the appropriate, and safe, distance from the master cylinder. Before I knew that though, I did remove the brake master cylinder and reached down to turn the rod, wouldn't turn, so I messed with it a bit and it just came out completely. Is that normal?

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Saturday, February 18th, 2023 AT 1:01 PM

KEN L

MASTER CERTIFIED MECHANIC
42,913 POSTS

I don't like that the rod just came out, but it might be normal. When the brakes are locked up can you loosen the master mounting nuts about three turns to see if the brakes unlock? Can you check the plunger in the rear of the master to see if it returns fully?

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Saturday, February 18th, 2023 AT 7:25 PM