Jim Grant's Tech Tips
‘94 Toyota Pickup 4x4, Disappearing Clutch
Q: I own a ‘94 Toyota Pickup 4x4 and have been having problems with my clutch. When I press the clutch, I lose pressure. However, if I let off the clutch, pressure is restored. The other day I was backing up and I was riding the clutch and lost pressure to where I was not able to shift out of reverse. I had to shut off my truck depress the clutch and start it again. I had a mechanic look at it, someone I know and trust, and he could not find anything wrong.
A: Your truck is equipped with a hydraulic clutch and it sounds as if the clutch master cylinder has an internal leak. When you step on the clutch pedal you’re pushing on a hydraulic piston that in turn pushes fluid to the clutch slave cylinder. The clutch slave cylinder pushes on an arm that releases the clutch. The clutch master cylinder has a reservoir of fluid that is most often brake fluid. If the fluid level is correct and no loss of fluid is noted, but the clutch loses pressure (fades away) it is likely that the seal on the clutch master cylinder’s piston is damaged and allowing fluid to leak by while under pressure. If you’re not losing fluid but you’re losing your clutch pedal my bet is that the clutch master cylinder needs to be replaced.