[R68GTO]

I noticed a leak on my driver side cylinder coming from the seal so it looks like its time for a replacement cylinder. While I'm at it, I am going to replace the aftermarket 4 foot pump with a correct 3 foot pump. What is the best way to flush out the whole system and replace the fluid? I am not sure what is in there now, but it looks like brake fluid so I would like to switch to tranny fluid.

[R68GTO]

Anyone do this? Is there a fluid that would be good to run through to clean out what is in there or should I just keep run tranny fluid through until all the contaminated stuff is out?

[mgoblue]

Unless the good cylinder is brand new, I advise replacing the whole set-up. You really only want to mess with that system once.

[rohrt]

I replace one cylinder just to have the other cylinder go bad the next year. Then the lines after that. It all started with replacing my pump.

To flush I would disconnect your lines from the pump and manually articulate the frame up and down.

I used ATF in my system. The red fluid shows up pretty well in the lines and make it a bit easier to check for air bubbles.

[Hunter98TA]

Originally Posted by rohrt

I replace one cylinder just to have the other cylinder go bad the next year. Then the lines after that. It all started with replacing my pump.

To flush I would disconnect your lines from the pump and manually articulate the frame up and down.

I used ATF in my system. The red fluid shows up pretty well in the lines and make it a bit easier to check for air bubbles.

I can see how a new pump could ruin the rest of the old system. I'm sure they're putting out a slightly higher pressure, causing the older, weaker parts to fail. I'll be getting around to this project in about a month. Not looking forward to it.

[rohrt]

Originally Posted by Hunter98TA

I can see how a new pump could ruin the rest of the old system. I'm sure they're putting out a slightly higher pressure, causing the older, weaker parts to fail. I'll be getting around to this project in about a month. Not looking forward to it.

YEP.

It was all 50 year old stuff. I tried to cheap my way out it by replacing a cylinder seal but it didnt last.

[Peter Serio]

I would say on any older 1950s or 1960s GM car they used to put brake fluid in the power top cars. If your planning on switching your fluid over to ATF it would be wise to replace both lift cylinders and the hoses plus the pump.

As an alternative if the motor and pump still work, I would take apart the pump clean each piece that touches fluid and replace ALL of the seals and O-rings with new. (You can buy a re-seal kit on ebay for not much $.) That way you make sure to remove all traces of the old brake fluid before you put back in fresh ATF.

Just FYI: In working on power tops the parts places that specialize in convertible parts always recommend replacing the lift cylinders in pairs.

[R68GTO]

I figured out that my system has hydraulic oil in it. Went to pull the plug on my used pump/motor and the plug broke off in the reservoir Now I have to take the reservoir off the pump to get that sucker out of there. Set it down on the bench for the night, was not in the right frame of mind to keep going. Will clean everything out and re-install with ATF.

[vidguy]

A long while back (17-20 years) I flushed mine and had the cylinders rebuilt by Hydro-E-lectric ,as one cylinder was leaking..
I bought their fluid. He described it as more of a Gear Oil. It is the color of oil not ATF. I still have the jug half full and it is still full of that. I think I flushed it once and refilled it since then a long while back when it stopped working. Turned out to be the electrical connector being fussy but I took it out to figure it out.