57 power top fluid?

[Dan H.]

I have been helping a friend with a 57 power top unit, we installed a new pump unit, rebuilt the valves, and flushed and installed ATF fluid instead of the brake fluid. Is ATF the best choice as a replacement fluid? Seems thicker and the motor runs slower than you would expect. Any suggestions?
Dan

[Edward S.]

Re: 57 power top fluid?

In early 90's I bought a 58 that was missing the entire power top unit - after much searching I found a complete unit on the west coast - bought it and had it installed ( using ATF ) never had a bit of trouble before I sold it 4 year's later. I was pleased with how it worked but I can't tell you anything about speed since ATF was the only thing I used. I remember how much better I slept at night knowing any type of leak was not going to lead to alot of damage, since I met some people who were using brake fluid in their units.

[Alexander C.]

Re: 57 power top fluid?

I would rather use silicone brake fluid

[John H.]

Re: 57 power top fluid?

I would rather use silicone brake fluid

Alex -

Probably not a good idea - DOT5 fluid doesn't like being agitated by a pump; it breaks up any entrained air into smaller and smaller bubbles and makes it almost impossible to bleed out. That's why you can't use it with ABS brake systems.

[Alexander C.]

Re: 57 power top fluid?

Alex -

Probably not a good idea - DOT5 fluid doesn't like being agitated by a pump; it breaks up any entrained air into smaller and smaller bubbles and makes it almost impossible to bleed out. That's why you can't use it with ABS brake systems.

Great to know, I had no idea! Thanks for the correction!

[Duke W.]

Re: 57 power top fluid?

If the system was originally designed for brake fluid, then ATF or any petroleum based hydraulic fluid may swell/soften/disintegrate the seals resulting in leaks as would happen if you installed petroleum based fluid in a brake system.

If it's already done, just wait and see what happens, but if everything starts leaking you will probably have to rebuild it again with all new rubber components. and use DOT 4 brake fluid.

BTW, we called Rob's cell phone at Coronado last weekend, but just got the message center. I guess you guys didn't make it. There were only four C2s, but, interestingly, two were running FI. Of course, a couple of FIA Cobras ran away from everyone.

Duke

[Loren L.]

Re: 57 power top fluid?

I believe I would use silicone brake fluid for startup and leak protection, ie, no loss of paint until you KNOW the system doesn't leak and it does work, followed by purging the system and installing regular brake fluid.

[Don H.]

Re: 57 power top fluid?

Great question. When I install my rebuilt unit in the early 90's I used silicone brake fluid. It work perfect for about 10 years then would not lift the top (but would the deck lid). I am ashamed to say I have never got it working again (& haven't spent any time on it). I have thought about switching to ATF when I fix it . . . soon I hope. Don H.

[Richard G.]

Re: 57 power top fluid?

I am rebuilding a PT pump and solenoid units and did a preliminary test on my workbench. On the bench I am using WD40 to clean and test the system. My pump output pressure is low, only 125 psi, so I called HYDRO-E-LECTRIC about the low pressure. I believe it should be 240-280 psi. They advise me they use mineral hydraulic pump oil
Richard (Driver 61)