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Post by topgun on Jul 10, 2004 21:54:19 GMT 11
When I stop at traffic lights on the hill the MU starts to roll slowly down the hill after 10 sec or so, and I have to press the brake pedal further and further to stop it ... Or use the handbrake...when the brake pedal is released its ok again, but goes soft after holding it for a few seconds.. There is no leaks at any of the calipers or master cylinder. Fluid level is good and not dropping (at least not noticible). This started only 2 days ago. I think the master cylinder seals are bypassing the fluid.. Am I correct  ?? If so is there a repair kit for it? is it same as Jackaroo? I need a pointer on this one... |
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Post by geeves on Jul 11, 2004 14:09:23 GMT 11
Have had this on a different car and a kit in the master cylinder should fix Cant verify if its the same kit though.
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Post by James W on Jul 12, 2004 8:28:31 GMT 11
This may be due to a loss of vacume, or a leak in the vacuum system if yours is vacuum assisted. Maybe? I'm not sure.
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Post by topgun on Jul 12, 2004 14:58:36 GMT 11
I'll check those out tonight
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Garth
Isuzu Senior
1989 Bighorn Irmsher R LWB
Posts: 164
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Post by Garth on Jul 13, 2004 19:02:58 GMT 11
I suggest looking at your vacuum system, it should provide vacuum for the brakes from the back of the alternator, I find that if my engine is runing at low revs then the brakes are very poor but not spongy.
If there are any leaks you should hear them, give the engine a few revs then turn it off and listen for hissing air around the master cylinder.
Another likely reason is air or water in your brake fluid. If you havent changed the fluid in the past year I suggest you bleed the complete system with new fluid to eliminate any air and remove water.
Brake fluid is hydroscopic so tends to break down over time, especially in humid climates, the water then boils when you brake hard, producing air bubbles that make the brakes spongy. Hope this helps
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Post by Roger on Jul 14, 2004 15:43:16 GMT 11
Another test if it is vacuum- Why not stop on that hill and when you start rolling back (in neutral) give it some gas to increase vacuum and see if it stops then.
Just a thought.
Cheers.
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MattMU
Isuzu Senior
Rodeo Now!
Posts: 206
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Post by MattMU on Jul 15, 2004 13:36:05 GMT 11
TopGun, This has NOTHING to do with your vacuum!! Vaccuum works in the opposite to what you are describing...think of it like this.
When you press the pedal the amount of effort you apply is assisted with the vaccuum. If you dont have any, the distance and pressure you can move the pedal is less! Test this by with the vehicle NOT running, pump the pedal a few times to ensure there is no vaccuum left and then, holding the pedal down relativly hard, start the veh, pedal should drop noticeably and then hold solid if system is ok.
If not....No vaccuum assistance and you need to check why, worn pump, slow leak, split diaphragm etc.
But as you said, the pedal is good and then starts to sink to the floor, is the opposite to having no vaccuum and suggests that there is internal leakage in the master cylinder (thats if there is no external leaks)
Let me know if my dribble isnt understandable ok and I will try again.
With the Master Kit...should be a Rodeo or Jack, get REPCO or ABS to look in their PBR book for the two listings and see if they have the same numbers for the rebuild kit. If not, make sure they have both on the shelf and when you are ready to go ripp it down and then take the parts into them to make sure which kit matches!
Goodluck and let us know how you go!
Matt.
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Post by topgun on Jul 16, 2004 11:02:57 GMT 11
I've been asking around and the mechanics and all point out the leaky seal in master cylinder.... Good news though this morning the problem went away... Perhaps some bit of dirt was stuck in the seal and now is gone ...So I'll wait a bit and research in the mean time about the rebuild kit type... Will let everyone know once I'll find out the part number... Thanks all for your input ...  |
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