Leif Holmberg Posted August 17, 2018 Share Posted August 17, 2018 I have a 1956 76C,years ago (5-6 years) I changed the brake fluid in the hole system for the top pump and filled up with Dextron 3 ,the same as I have in my Dynaflow and power steering. But the much longer time it takes to have the the top up or down comparing when used brake fluid are frustrating,it takes 3-4 times longer now. Any idee what oil-fluid to use to have it go faster again,I don`t want to use the old type of brake fluid,but how about the newer type of brake fluid (water resisted ?silicon fluid) Leif in Sweden. Link to comment Share on other sites More sharing options...
JohnD1956 Posted August 17, 2018 Share Posted August 17, 2018 I do not have the answer you are looking for but I would suggest test mixing the fluids to see if they blend or separate over the period of a few days or weeks. I say this only because the advice I have heard with the silicone brake fluid is to only use it with all new parts, and I wonder how you'll clean out all the old fluids before installing a third type of fluid. I would suggest a brake fluid/ dexron mix, a dexron/silicone mix, and a mix with all three. Small glass jars on a shelf for a week ought to give you some idea how the fluids will, and have. blended inside your system already. I also assume you have looked for a kinked line in your hydraulics just to rule that out as the culprit in the extra time needed since the prior fluid change. But maybe some new flex lines are called for here? Link to comment Share on other sites More sharing options...
old-tank Posted August 17, 2018 Share Posted August 17, 2018 Check the fluid level again. Check pressure at pump (230-250 psi). Raise top to 1/2 up and stop. Now observe each cylinder for smooth and even bilateral operation. Cycle the top at least 5 times to purge any air. Report back. Link to comment Share on other sites More sharing options...
KongaMan Posted August 17, 2018 Share Posted August 17, 2018 Wouldn't suspect that the problem is the type of fluid, but the fluid level or a hydraulic issue. It sounds like you have air in the system (does the pump "grind"?) or a loss of pressure. Also, changing fluids is not as simply as draining the tank and refilling it with something else. You need to purge the pump, lines, and cylinders first. That can be a PITA. Don't discount the possibility of a leak (perhaps internal to a cylinder or the pump). You didn't say how old the components are (original?), but seals can go bad. It probably wouldn't hurt to rebuild the pump if that hasn't been done. Finally, you can do a quick sanity check on the system. With the top up, disconnect the cylinders from the top mechanism. Run them up and down a few times (but don't run them up all the way). Do the cylinders move at the same speed? Link to comment Share on other sites More sharing options...
Bhigdog Posted August 17, 2018 Share Posted August 17, 2018 Wondering how you purged the system of both old fluid and new unwanted air. Keep in mind the cylinders are double acting and fluid and/or air have to be purged from both sides of the piston. Very doubtful type of fluid changes the rate of travel as much as you say........Bob 1 Link to comment Share on other sites More sharing options...
Leif Holmberg Posted August 18, 2018 Author Share Posted August 18, 2018 Just remember that the speed was much slower from the first time when I changed the from brake fluid to Dextron 3. Everything is original parts when car was new ,exept the pump gear that was new made 20 years ago,pressure tested the pump after new gears and it was a pressure as showed in the Shop Manual. Leif in Sweden. Link to comment Share on other sites More sharing options...
1953mack Posted August 18, 2018 Share Posted August 18, 2018 (edited) There should be an air gap in your firewall pump's reservoir. Did you overfill it? Here are a few suggestions from Hydro-E-Lectric if you haven't seen these already. http://www.hydroe.com/Tips_-_Cylinders__amp__Pumps.html Al Malachowski BCA #8965 "500 Miles West of Flint" Edited August 18, 2018 by 1953mack (see edit history) Link to comment Share on other sites More sharing options...
KongaMan Posted August 19, 2018 Share Posted August 19, 2018 18 hours ago, Leif Holmberg said: Just remember that the speed was much slower from the first time when I changed the from brake fluid to Dextron 3. Which might suggest that the system was not completely purged of air. Have you checked the fluid level lately? 18 hours ago, Leif Holmberg said: Everything is original parts when car was new ,exept the pump gear that was new made 20 years ago, Which might suggest a problem in one or both cylinders. Remember, they're 60 years old. Again, try testing the system without the top: disconnect the cylinders from the top and run them up and down a few times with the plug removed from the reservoir. Do they move smoothly and at the same speed? Does the pump grind? What did you do to change fluid? What is the exact procedure you used to flush the brake fluid and fill with Dexron? Link to comment Share on other sites More sharing options...
Leif Holmberg Posted August 19, 2018 Author Share Posted August 19, 2018 I changed the fluid just becuse don`t want to damage the floor in my car if I got a leakage.I have seen after arond 10-15 years that the tubes are "breating" and left a thin surface of rust on the floor. Why I asked is that I don`t want to do a lot of test job on my car,to change the oil are the easiest to do if I can find an useful oil that are thinner the Dextron 3. Leif in Sweden. Link to comment Share on other sites More sharing options...
old-tank Posted August 19, 2018 Share Posted August 19, 2018 Follow the suggestions in the previous posts. ATF we know will work with new components; maybe your original components are not compatible with ATF... much like adding ATF to the brake master cylinder. If you still think ATF is too viscous, try DEXRON-VI which has a slightly lower viscosity. You may need to replace all components. Follow the suggestions in the previous posts. Link to comment Share on other sites More sharing options...
KongaMan Posted August 19, 2018 Share Posted August 19, 2018 6 hours ago, Leif Holmberg said: I changed the fluid just becuse don`t want to damage the floor in my car if I got a leakage. Perfectly sensible. 6 hours ago, Leif Holmberg said: Why I asked is that I don`t want to do a lot of test job on my car,to change the oil are the easiest to do if I can find an useful oil that are thinner the Dextron 3. Unfortunately, the only way you're going to conclusively identify the problem is by doing a bit of testing. OTOH, if you're convinced that the fluid is the problem and that the system is purged of air and all seals and components are functioning perfectly and you need a thinner fluid, then you could probably fill the system with Marvel Mystery Oil. I just went through this exercise: 55-year old components, working fine, but a slight leak. I opted to replace the hoses and cylinders, rebuild the pump, and switch to ATF. I switched to ATF because it's friendlier to the surroundings in the event of a leak. I replaced the hoses and cylinders because a) purging them of brake fluid is a time-consuming, potentially messy process, b) a blown hose or seal would be a disaster even with ATF (think you can clean ATF out of your trunk liner?), and c) relying on decades-old hoses and seals in a high-pressure system is a gamble wherein the odds are getting longer by the day. As a practical matter, installing new cylinders and hoses is probably faster and easier than doing a proper job of flushing the old ones, and using new components will put you in a better place. Yes, it stinks spending the $300 or so on the parts, but you'll likely spend more than that if one of your old parts blows. 2 Link to comment Share on other sites More sharing options...
NTX5467 Posted August 19, 2018 Share Posted August 19, 2018 The original system was configured for the brake fluids of the earlier 1950s, as that was something that ALL service facilities had "on the shelf". ATF was still not as prevalent back then, as there were still a bunch of manual transmissions still out there (which took the same lube as the rear axle, generally). Brake fluid, by necessity, has a very low viscosity number. ATF is more like 10W motor oil, i.e., thicker . . . which might be an issue in a convertible top fluid mechanism not designed for it. Then there's the issue of seals and hoses. Leaks of brake fluid can be major issues, even with a small leak. ATF not so much, but still issues. Silicon brake fluid will separate from normal brake fluid, over time, but was alleged to not cause any issues when it did, in the brake system. Seals in the system are designed from "brake fluid", which generally means a different rubber compound than to effectively seal ATF. Might work for a while, but long-term would be a different issue, to me. Modern brake fluid specs are generally related to heat tolerance and moisture absorption. There are two specs for DOT 5 fluids, one for normal fluid and another for synthetic fluid? The car looks nice, but the issue of the convertible top mechanism would be more of a "maintenance" issue, for ANY convertible. Changing the hydraulics to a more modern fluid would be a good move, typically. I concur that changing components can take less time than doing "the purges" your system might need. Time counts for something! Peace of mind in the future can be "priceless". Eventually, existing components will fail (age and deterioration of seals/lines, etc.), so getting it done now would be a plus, to me. Check with a local heavy-duty truck hydraulics shop to see if they can rebuild your hydraulic rams and make new lines to work with the fluids THEY use in your part of the world. This way, all of your contacts will be "local" rather than otherwise. Just some thoughts, NTX54676 1 Link to comment Share on other sites More sharing options...
Leif Holmberg Posted August 20, 2018 Author Share Posted August 20, 2018 Thanks for all replies. This`s what I red before I changed to ATF Dextron 3 on my 1956 convertible.http://www.hydroe.com/Tips_-_Cylinders__amp__Pumps.html Later this summer I will test the thinner type of oil at first,if it not will work properly (fast enough) I probebly have to change the cylinders,if remember right someone here in Sweden made new cylinders. Thanks from Leif in Sweden. Link to comment Share on other sites More sharing options...
Rosiesdad Posted August 22, 2018 Share Posted August 22, 2018 Well I'm afraid I have some bad news for you. The original seals in Buick hydraulic systems are most likely natural rubber. Brake fluid is not a hydrocarbon based fluid and works fine with rubber. ATF IS hydrocarbon based fluid. It DISSOLVES rubber seals. I switched from brake fluid to ATF also. Within a month all my window and top hydraulic seals needed replacement. The seals had turned to a goo like mush. With six new cylinders with non-rubber seals all works fine again. Cheers Phil Link to comment Share on other sites More sharing options...
Leif Holmberg Posted August 23, 2018 Author Share Posted August 23, 2018 (edited) Phil. Before I chanced the oil 5-6 years ago I looked at what this shop told,the top still work after all those years,but I want it to a little bit faster. http://redirect.viglink.com/?format=go&jsonp=vglnk_153500515259317&key=c81177253a52b296f324af540b3d8eea&libId=jl66b6yf010004qo000DAnnwhkvdm&loc=http%3A%2F%2Fforums.aaca.org%2Ftopic%2F314102-1956-convertible-oil-liquide%2F&v=1&out=http%3A%2F%2Fwww.hydroe.com%2FTips_-_Cylinders__amp__Pumps.html&ref=http%3A%2F%2Fforums.aaca.org%2Fforum%2F57-buick-post-war%2F&title=1956 Convertible oil-liquide%3F - Buick - Post War - Antique Automobile Club of America - Discussion Forums&txt=http%3A%2F%2Fwww.hydroe.com%2FTips_-_Cylinders__amp__Pumps.html Leif in Sweden Edited August 23, 2018 by Leif Holmberg (see edit history) Link to comment Share on other sites More sharing options...
Rosiesdad Posted August 30, 2018 Share Posted August 30, 2018 According to the link '53 appears to be when they went to synthetic rubber material. Good to know! 1 Link to comment Share on other sites More sharing options...
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