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Discussion Starter #1
Recently changed rotors/pads and drums/wheel cylinders/shoes/all drum hardware. Had a leaking wheel cylinder.

Bled the brakes with truck off. Got air out of the lines. Very firm pedal with truck off after a couple pumps.

Issue is while driving and I hit the brakes, it’s a slow stop without much force. I can’t get the ABS to kick on even with wet roads.

My thoughts are master cylinder internal seal issue.

Any thoughts/experiences?

Truck is an 09 z85 with 175k
 

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Were you having a problem of firm braking before you did those repairs? If not , I would think it wouldn't be an issue with the master cylinder.Check the metal brake line at the wheel cylinder to see if you cracked it when you did the replacement of the old one. I'm sure your 11 year old truck didn't want to cooperate with you when you removed the cylinder and you needed to apply a good deal of muscle to get it off.
Also are you one of those guys that forces the caliper piston back into the bore before first cracking open the bleeder screw? I hope not , the ABS module doesn't like old nasty brake fluid being forced back into it . That may be the cause of the ABS not kicking in.
I would first check the brake line then disconnect the battery for a bit in hopes that it may "reset" the ABS system.
 

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Discussion Starter #3
After driving awhile the truck brakes better.
I plan to readjust the rears, I don’t think I have them “tight” enough on the drums.
When I pushed the caliper in I went very slowly but didn’t have the bleeder open.
I’ve done a few brake booster checks and all pass, including the check valve. So I’m left with either internal master cylinder leak, abs needs to be bleed.
 

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Discussion Starter #4
I did find this today. The picture is the boot that’s over where the piston/metal rod attaches from break pedal to brake booster. No clue what the orange sticky substance is
342412
 

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The rear drums self adjust when braking while driving backwards. Get yourself on a long driveway and just drive backwards and pump the brakes a bit and they should right themselves. If not, you may have assembled the brake hardware wrong, or the "star wheel" won't turn because the adjuster is stuck.
 

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I did find this today. The picture is the boot that’s over where the piston/metal rod attaches from break pedal to brake booster. No clue what the orange sticky substance is View attachment 342412
Just a guess, but its a mixture of oil and moisture that is coming in the booster from the vacuum line to the intake manifold, and it's making its way past the seal along the rod. Are you losing oil?

On second thought, that oil would be going to the opposite side of the brake booster diaphragm...is it maybe rust from a leaky windshield coming down the back of the firewall?
 

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Discussion Starter #7
Thanks for the insight you guys.
I’ll give that backwards dukes of hazard driving a go.
I did have terrible leaking from a torn grommet a long time ago, since fixed but it’s totally possible. Nothing drips, just nasty😷
 
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