Questions and Answers

Sierra 1500 Contaminated Clutch Fluid Q. Hi Vincent, I have a 1993 GMC Sierra 1500, 4.3 liter fuel injection, standard 5-speed transmission with 220,000 kilometers on it. I am having a problem with the hydraulic clutch. I've had it for about 1½ years and during this time a have replaced the clutch slave cylinder, bracket broke off, and the line rusted through, new line installed and bled, but the clutch has always worked perfectly.

The other morning I went to start it up and the clutch pedal went right to the floor with very little back pressure. I thought the line blew out again but there was no fluid on the ground. I removed the reservoir cover and it was full but the fluid looked very contaminated, looked like milky globs.

I used an eye dropper to remove all the old fluid and cleaned out the reservoir with a paper towel. It was very dirty and looked rusty on the bottom, plastic reservoir. I refilled the reservoir and retried but it didn't improve. I drove it around the block in second gear but it was very rough and didn't seem like it was engaging fully.

This happened out of the blue. I have had no problems up til now. Could the piston seals in the new slave cylinder be blown?

Thanks,
Chris
St. Catharines, ON

A. The fluid may have been contaminated with something other than brake fluid. Have you tried to bleed the unit at the slave cylinder? The master cylinder could also be allowing fluid past it's seals. Crack the bleeder valve and let it gravity bleed while someone watches the fluid level, making sure it doesn't go dry.