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Discussion Starter · #1 ·
Working on my son's 98 Trooper and replaced rotors and pads on the front. On the test drive the brakes seemed mushy and something just isn't right. Here are other facts:


  • 1) I can pump the brakes three times real quick and then they feel firm
    2) If I wait ten seconds after pumping they go mushy again
    3) Son accidentally loosened the connection where the brake hose attached to the caliper. Maybe a couple of tablespoons on brake fluid came out before he realized there was a problem and retightened. We did not bleed brakes after this little incident.
    4) No other breaches into the brake system occurred
    5) Fluid reservoir is full

My hunch is that he managed to get some air into that line when he loosened the wrong bolt. When I pump three times I am thinking that I am just compressing the bubbles and then things work. However, when I let off for ten seconds the bubbles expand and push the fluid back into the reservoir.

I'd like to hear some other ideas as to the cause or affirmation that my thoughts are correct before I tear back into things again.

Regards,
Brent
 

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Yep, it sounds like air in the line. Recommend bleeding the line.
 

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I personally would bleed all the lines. I don't think air got in the other lines but I suspect you have old, tired fluid throughout the system. Now is as good a time as any to replace the fluid. If so equipped, just make sure you know the proper procedure for bleeding ABS brakes. It is not as simple as just following a particular wheel bleeding order.
 

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Blead the brakes, or have someone do it for you. Brake shops should do this for like $20-$40. This isn't something to just play around with, it's a safety issue, and should be addressed by someone who knows what they're doing.
 

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Yep, I'm gonna agree with the other folks on this one. If you decide to bleed-em yourself, just go ahead and flush the system to replace all the old fluid. You can order some speedvalves (I think that's what there called) but you'll have to order them, as no one seems to carry them in stock. Or get one one of those one-man bleeder kits from a local autoparts store, but from what I've read online they're only good for a few uses.
 

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If the pedal "sinks" under constant pressure, it's a master cylinder (or a leak), not air in the lines.

Bleeding them won't hurt anything, and in fact is a really good idea, but it may not help the mushy pedal if the master cylinder is worn out.

Pump the pedal a couple of times, and then hold with constant pressure - if the pedal slowly sinks to the floor, you need a master cylinder, or you have a leak.
 
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