Wheel cylinder keeps blowing out on one side

Asked by Jan 16, 2016 at 11:11 PM about the 2002 Pontiac Grand Am SE Coupe

Question type: Maintenance & Repair

One side of my wheel cylinder keeps blowing out I
have rear drum brakes and put a new wheel
cylinder on and one side keeps popping off and
spewing brake fluid everywhere. Any solutions?

19 Answers


You have too much travel for the wheel cylinder, breaks are not adjusted. Adjust the rear break shoes up to the drum so they are just dragging against the drums.

1 of 1 people found this helpful.

Did that but it still keeps blowing out on one side


Then check the E-break spreader bar, it could holding the shoes open. Push in on the shoes both sides at the wheel cylinder, The radius cut outs in the top of each shoe seats into the center round post at the top. Then you adjust them.

1 of 1 people found this helpful.

Okay I tried that put it all back together bleed the breaks and tested em and when I started the car and pumped the breaks a few times the seal blew again. Its a new wheel cylinder as well. Any other suggestions?


Does it feel like a good break pedal before this happens? If by chance the wheel cylinder is not defective, it is possible the proportional valve may be messed up. This regulates the pressure going to the rear wheel cylinders. There could be too much pressure for the wheel cylinder.

1 of 1 people found this helpful.

When the wheel cylinder is blowing, does the piston come out?

1 of 1 people found this helpful.

Yea the piston comes out.


Wow this one is tough, even if the proportional valve is messed up the piston should not have enough room to get pop out, As mentioned earlier check for proper adjustment and is the same side always blowing out?? check the brake shoe to see where the shoe and wheel cylinder meet they are connecting properly and the surfaces are flat.


The grand am I believe have two sizes wheel cylinders and shoes, just something else to look at

Yea its the same side every time.


Hello there Steven, hope everything is ok.

1 of 1 people found this helpful.

I was looking up parts for this, Not 2 different sizes for this one. Possible they boxed up the wrong one? Wrong wheel cylinder? There is no way that piston could come out if the shoes are together at the top post, and all the way in on the star adjuster, and the E-break is not holding it up. Compare it to the other side.

1 of 1 people found this helpful.

Alright thank you ill try that.


I doubt this is the problem but make sure the brake drum is not worn excessively. In any case the cause is excessive piston travel. You may want to replace the other brake hardware while you are at it.


Hey Rowefast, all is good on this side of the world, Hope you had good holidays, This is a odd problem, one I would like to see for myself, one wheel cylinder on one side blowing out. kinda rules out most possibilities and probabilities but none the less its still happening. How many times has this happened on the same wheel cylinder on the same side? We all can agree that this is a piston over travel problem but if the drum is not over sized, the correct wheel cylinder, shoes properly adjusted, ebrake lever in the proper position this can not happen.


Right, Should request a good picture to post so we can see it. I say the shoes are not together and adjusted wright, You know, I bet this guy is dealing with worn out shoes and drums, and trying to fix a wheel cylinder problem. This would cause over-travel of the piston..

1 of 1 people found this helpful.

Where are my manors, Hey there Steven B, all is good.

I had the same problem and on inspection I found the return spring on the bottom of the shoe unhooked and the shoe had slipped behind the stop allowing the shoe expand too far and the piston to pop out

I can not believe hearing "it can't happen" over and over. It happened to me 7x already. One wheel cylinder, repaced twice.

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