Clutch Hydraulic Problems

[bobinyelm]

Originally Posted by jhv48

So, just how long does it take to boil the hydraulic fluid?

Just sitting and idling with no air circulating in the engine compartment is more than enough time to boil the fluid. The headers can reach temps much greater than the boiling point of most brake fluids if not shielded from radiating their heat directly onto a metal hydraulic line. Shoot a laser temp gauge directly onto the line after the car has been idling for ten minutes and see what the exterior temp reads. You may be surprised.

I am sure you're right, and maybe having the hood open was not a better way to try to encourage airflow. Maybe hood down with the radiator fan on would have been better.

I repeated the experiment tonight (engine idling, hood open) and tonight no problem-clutch as smooth as butter.

I did notice that even with the two BDR shields in place, the vacuum brake booster and the short brake line runs from the brake master through the inner fender were too hot to touch in 5 minutes flat.

The shields were burning hot, and despite being silver (low emissivity), were radiating an amazing amount of heat up at the hydraulic cylinders. I may try to find some of the thin wool insulation with silver foil on on side (often sold for firewalls, transmission tunnels, or undersides of hoods) to mount foil-up on top of the shields to cut down on the radiation.

The idea of putting some kind of fan in there blowing cool air in (or hot air out of the side grill) makes more sense than ever to me as well.

And, once the fluid is boiling, your clutch becomes useless until the fan comes on and blows some air on the lines to reduce the temp or you take the car for a drive and the air circulating around the engine brings the temp down.

That's why so many of these cars have troubles when stuck in traffic but operate fine once on the hiway.

I didn't know that was a problem until these postings, actually.

Don't rule out the m/c just yet either.

Yep. Nothing's off the table. Strange that whatever happened last time didn't happen tonight, though the outside air temp was 15 degrees cooler than the last time.

Bob