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Discussion Starter #1
Well I have been driving the car around in the very hot Virginia Summer (~103 degrees and 90% humidity most days). This has revealed an issue the other day where I all of a sudden started losing pressure when depressing my clutch pedal. I found it odd as clutch line is braided stainless steel, my slave cylinder is brand new, and I just replaced my master cylinder and put a new bushing in the clutch pedal assembly. So I was scratching my head when it hit me, it is only happening on occasion when the car is at full operating temp, and it's extremely hot outside.
I went to the beach today and checked the clutch fluid level when I got there, it was at the same perfect level and no fluid was lost, but the fluid and reservoir were VERY hot. This led me to.......

Conclusion: My theory is that my clutch line is running too close to my catalytic converter and the rear of my engine block. At full operating temperatures, augmented by the extreme temperatures of the catalytic converter, I believe the DOT 3 brake fluid in my clutch line is effectively BOILING in my clutch system producing air pockets and bubbles which are reducing my pedal feel and effectiveness.

Question: I am going to attempt to fix the situation by clipping the line to an area away from any extreme heat sources, but I am additionally wondering if maybe I could run some ATE DOT 4 Super Blue fluid in the clutch system because it has a MUCH higher boiling point, just to put the ultimate fix in the system. Can the clutch system handle it? I would assume so, but any input would be valued. :)
 

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Yes, DOT4 will be fine. DOT 3 and 4 can mix without any issues, so just drain out what you can of the DOT3 and refill it with 4 and bleed it. DOT5 is where it becomes a problem where everything would have to be replaced and brand new before switching over.
 

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Discussion Starter #4
It has the factory SC heat wrap on the line, but it's marginally helpful, it's only 1 ft in length for the CAT area lol.
 

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I agree DOT5 would be a problem. However if you can find it I would go with DOT 5.1, it's fully compatible and more heat resistant than DOT4.
 

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Discussion Starter #6
I agree DOT5 would be a problem. However if you can find it I would go with DOT 5.1, it's fully compatible and more heat resistant than DOT4.
I can get my hands on 5.1, however if I can run DOT 4 in the system, I think it will have more than enough boiling resistance for what I need. :D
 

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Discussion Starter #7
Well I changed out the fluid today for the ATE DOT 4 and I secured the line away from the exhaust, cats, and back of the engine. When I first got under the car the line was bare up against the block, and part of it was resting on the exhaust near the manifold. The clutch pressure is more consistent now, even though I still have some bubbles left in the lines that will bleed themselves out, it feels good. So if anyone loses pressure when in hot weather, just check where your clutch line is! :cool:
 
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