Lately I have noticed that my left front wheel gets very hot, and there is a more pronounced warp in the disc while braking.

Recently, I installed a new master brake cylinder and blead the system from farthest wheel to closest wheel, in that order.

Is it possible I still have air in the left front caliper brake line and cylinder that could cause the pads to extend a bit while driving without braking?

My anti-lock light has been coming on every once in a while lately too.

Any suggestions? ...........BB

Wheel bearings possibly dragging causing friction and heat?

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Adam Lumsden
(83) 300D
Vice-President of the MBCA International Stars Section

Does the wheel turn free? Maybe the pads are draging. If your calipars are not releasing the brake pressure them it would make plenty of heat. Air in the system will not make the brakes drag.

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82 Rabbit diesel (first d), 84 Jetta turbo d (300k when sold), 83 240d (305k when sold), 84 F250 6.9d w/Banks turbo(parts truck), 86 F250 6 cyl.gasser(waiting for 6.9d), 84 300d ( 347k Sold 8/04), Y2k New Bettle TDI (185k miles), 95 740IL (wifes), 87 300TD (206k Sold 7/05), 05 Passat TDI Wagon

My money is on a sticking caliper. If you jack the car up and spin the offending wheel by hand, you will be able to easily determine if that is the case. Did you do any brake maintenance besides the master cylinder?

I agree. Press the brake pedal firmly and then release. Spin the offending wheel by hand and then spin the opposite wheel by hand. They should be about the same. My guess is that you won't be able to spin the offending wheel. This indicates a bad caliper or a bad brake hose. Crack the bleeder screw and let off any pressure. If you can now turn the wheel, the brake hose is bad. If nothing changed, the caliper is the most likely culprit.

BTW, my rear brakes have failed for the third time. I have to get out there and rebuild the LR caliper due to a pretty severe leak from the piston seal.

Perhaps a sticky caliper, perhaps an internally-collapsed brake hose that is slowing the return flow of brake fluid, thus keeping the pressure on the caliper (and thereby pads).

Thank you all for your responses.

Tomorrow I will get under there and investigate. The pads were changed last summer, but nothing has ever been done on wheel brake hydraulic cylinders to my knowledge. Also the anti-lock light is coming on now, but I'm not sure the two issues are related. .BB

For those interested, I found my left front caliper hydraulic piston had a little rust around it, so I pumped up the brakes so the piston would extend outward, but not enough to pop it out, then peeled back the rubber boot and cleaned it up of what appeared to be sticky grease with spots of rust then coated it with mystery oil, slipped the boot back on then worked the piston in and out several times. Now it's fine and is not draging anymore. No wonder why my MPG's were off a little lately!

Thanks for all your suggestions and thoughts..........BB

Petroleum products should never be used on brake components. The sticky grease was likely brake fluid that had leaked past the caliper seal. I would keep close tabs on the caliper. Chances are slim that you problems are over.

Buy yourself a rebuild kit(contains new seals and rings for the piston) pull the pistons out and clean everything up then reasemble it and call it rebuilt.
As stated above do not use any petroleum products during reassembly use brake fluid or even better silcone grease. Until they are taken apart the sticking condition will keep coming back.

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82 Rabbit diesel (first d), 84 Jetta turbo d (300k when sold), 83 240d (305k when sold), 84 F250 6.9d w/Banks turbo(parts truck), 86 F250 6 cyl.gasser(waiting for 6.9d), 84 300d ( 347k Sold 8/04), Y2k New Bettle TDI (185k miles), 95 740IL (wifes), 87 300TD (206k Sold 7/05), 05 Passat TDI Wagon

If there was "grease" and rust in there, the piston seal is bad and so is the dust boot (probably from running the brake pads down to nothing at some point).

Get TWO caliper rebuild kits, do both front calipers (this is really very easy if the pistons aren't stuck), and change the brake fluid.

I would also recommend new rotors and pads while you are at it, unless the pads are nearly new. If the rotor is warped, it's junk (can't be turned). Likely under thickness anyway -- is there a distinct "lip" at the outer edge?

Do this as soon as you can, that caliper has dirt in the piston bore, and will surely stick again, or worse, the seal will start leaking enough to prevent the brakes working.

Do the rear calipers next pad change or when you get some $ ahead. Brakes are rather critical to driving.....

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I just found kits available that include seal and rubber boots. Didn't think they would be available, but they are, and cheap too!

Thanks guys................BB