Cold Weather Hydraulic Clutch Problems

[mechtech2]

At only 30F, you seem to have mechanical problems, not hydraulic ones.
The fluid should behave perfectly.
Some parts are not mating up right.

 

[TallPaul]

I have the original master cylinder (1995 F150), so perhaps it is just worn out enough to work but when it's cold the tolerances in the throwout, pp, etc put it over the edge. The other thought is the hydraulic line is also original and could possibly have some give, that is, maybe it is bulging a little resulting in less stroke at the slave. Again the cold weather being the tipping point. If so, replacement of the master cylinder and line, should result in a higher engagement point, so that when the engagement point gets lower in cold weather, it is still above the floor.

 

[mechtech2]

Good thinking. Sounds like a plan.

BTW, I stated that poorly - I did not mean that the hydraulic system could not be at fault, just that the fluid was not the problem at those temps.

 

[TallPaul]

Well my hope is that it is a mechanical problem caused by a hydraulic problem. There is no leak and if there is air it is not much because pumping the pedal does not help. It goes in next Thursday but I may bump it to Monday if possible.

 

[TallPaul]

Stopped by the shop on the way home today. Mechanic said he did not think the master cylinder was the problem, that it needed a thin shim behind the flywheel to account for wear because with the flywheel wear, the slave cylinder has to reach just a tad farther. The easy way to deal with it is to adjust the stroke in the pedal linkage. There are many tricks, the first of which is to rip the 5/32" rubber pad off the pedal stop, so he did. Definitely more stroke in the master cylinder. Tomorrow morning at about 30F will tell if it helped much. If it works tomorrow and there seems to be a little leeway, might make it through winter. Not sure what the colder weather will do, but if shrinkage due to temperature is linear, it will get a lot worse at 0F.

 

[TallPaul]

Problem resolved. It was the master cylinder. Had it replaced last thursday and this morning at 10F it performed flawlessly. Slipped right into gear. Mechanic showed me that the old MC piston was not coming all the way back but stopping about half inch short, effectively reducing the stroke.

 

[jc1990]

sounds like exact same problem had with my 94 ranger it needed a slave cylinder problem solved

 

[TallPaul]

Nobody seems to think that the master cylinder is bad unless it is leaking. To be fair, the shop that was advocating a shim behind the flywheel never got to inspect it, and hopefully woudl have done the MC. I was going to do the MC a couple months ago but they didn't think it would be the problem.

Next clutch better shim it though as the pedal is lower than ever before. I am amazed that sucn minimal differnce can make such a difference in the clutch pedal. Also, instead of shimming the flywheel, would make more sense to put some thin washers behind the slave when mounting it to the front of the tranny. It needs a big inspection plate that can be removed, then the slave could be shimmed wihtout dropping the tranny.

New clutch, new brake lines, a lot of other new stuff, this truck is ready for another 100,000 miles if the leak above the windshield is not the kiss of death! I don't ever want to give up this truck, wife hates it and it will be a battle to get another manual tranny as she won't/can't drive it. Funny thing she drove her brother's 3 on the column station wagon many years ago in teh snow Wisconsin winter and got from point A to B.