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my 1953 hydraulic convertible top has brake fluid in it. can I replace it with atf. is there a problem if I cant get it all out and the new atf mixes with brake fluid????


Thanks
Ken

ATF was recommended by some at one Packard club many years ago and a flush was required. I don't know if it is still being done. There is a thread on the AACA Buick forum which also mentions itforums.aaca.org/f162/hydraulic-window-pr ... -buick-super-305467.html#post897937 and also suggests getting in touch with Hydro-E-Lectric for more detailed instructions.

OE fill was brake fluid (DOT3). What are you trying to accomplish by switching to something else?

Flush or no, I doubt if the original hose material will hold up to ATF. Even brand new fuel hose won't hold up to that. There is a special type of hose material made specifically for use with ATF, which should be available, in bulk, at any good parts store.

However, I can't say whether or not you could have new hose assemblies fabricated, locally, with this material to replace the originals.

ATF, hands down, is the fluid to use. The hydraulic rebuilders won't warranty their rams and hydraulic components for nearly as long if you use brake fluid. Brake fluid absorbs moisture from the atmosphere when exposed to the air, and even in a closed system, like the brake system, it still absorbs enough moisture in two years to lower the boiling point sufficient to require a change in fluid every two years.

BUT the Packard hydroelectric system is open to the atmosphere. Which means that brake fluid is deteriorating from the moment you pour it in. ATF, on the other hand, doesn't do that.

The only issue, as BH alluded to, is that hydraulic hoses prior to about 1953 don't hold up well to ATF (they tend to swell). The easy test is to remove any older hoses and soak them in ATF for a day or so. If there's no change, you're good to go. If there is, any convertible top shop can make you a hose, or you can buy new hoses from the specialty vendors.

The flush to convert from brake fluid to ATF isn't difficult-- do it just as you would a normal fluid change. To speed things up, I'll exhaust most of the fluid from the system by removing the hose at the farthest hydraulic cylinder and running the pump. Then fill the system with ATF and repeat, cycling all hydraulic components to their most collapsed state, back to fully extended. Empty the system again, fill with ATF, bleed it per the service manual, and you should be good to go.