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| | | | Joined: Sep 2006 Posts: 1,997 Big Bolt Forum Co-moderator | | Big Bolt Forum Co-moderator Joined: Sep 2006 Posts: 1,997 | Hello, I need to top up my master cylinder in 1948 two ton and before I add more fluid (looking for a leak) I want to know if I can use the synthetic dot 3 fluid. I didn't see anything else at the local automotive supply store, and I don't think I could trust asking the young lad behind the counter about the synthetic fluid. Is all brake fluid synthetic now and if the person who owned the truck before me put in non-synthetic can I mix them?
A day without laughter is a day wasted- Charlie Chaplin
When wrestling a grizzly bear, you have to keep at it until the bear gets tired, not when you get tired. 1948 Chevy 2-Ton | | | | | Joined: Jan 2003 Posts: 354 'Bolter | | 'Bolter Joined: Jan 2003 Posts: 354 | Most all brake fluids for at least the last 40 years or so are glycol ether based. The glycol ethers generally come from a vareity of petroleum sources including natural gas. Any DOT labeled brake fluid except DOT 5 is required to be compatible with any other DOT labeled brake fluid. Some of the DOT 5 fluids are silicone based and are not compatible.
Harold Wilson
41 Chevy 3/4 Ton
| | | | | Joined: Apr 2007 Posts: 38 Wrench Fetcher | | Wrench Fetcher Joined: Apr 2007 Posts: 38 | You cannot mix DOT 5 and other types. DOT 5 silcone is a purple color. Its good stuff but you need to do a all new brake system or at least flush the system well with a brake cleaner.
You can mix dot 4 and dot 3 | | | | | Joined: Jan 2003 Posts: 354 'Bolter | | 'Bolter Joined: Jan 2003 Posts: 354 | Any DOT 3 fluid should be OK unless the previous owner put in DOT 5.
Harold Wilson
41 Chevy 3/4 Ton
| | | | | Joined: Jan 2003 Posts: 354 'Bolter | | 'Bolter Joined: Jan 2003 Posts: 354 | There is no non-synthetic brake fluid. All brake fluid is synthetic. It's all "synthesized".
Harold Wilson
41 Chevy 3/4 Ton
| | | | | Joined: May 2006 Posts: 8,351 'Bolter | | 'Bolter Joined: May 2006 Posts: 8,351 | There is synthetic DOT3 and 4. I would be leary of mixing though. And stay away from Dot 5. I tried it with all new components, it made the system leak.
If you can't find regular DOT3 at the store you go to, try a different one. Regular DOT3 is still availible.
Bill Burmeister
| | | | | Joined: Sep 2006 Posts: 1,997 Big Bolt Forum Co-moderator | | Big Bolt Forum Co-moderator Joined: Sep 2006 Posts: 1,997 | Thanks all. I top it up, pumped the air out and now I have brakes. However, in the future before I take this beast out on the road I would like to inspect the brakes. Mine is a 48 two ton and you have to pull the hubs just to take the drums off. There doesn't appear to be a leak, that I can find, but where did the fluid go???????????.
A day without laughter is a day wasted- Charlie Chaplin
When wrestling a grizzly bear, you have to keep at it until the bear gets tired, not when you get tired. 1948 Chevy 2-Ton | | | | | Joined: Apr 2007 Posts: 1,038 'Bolter | | 'Bolter Joined: Apr 2007 Posts: 1,038 | Since you have a 2 ton, do you have a brake booster on your truck? If you have a Hydrovac brake booster, you can leak into the cannister and you won't see an external leak. Had that happen on my Diamond T. You can leak several pints of brake fluid into that vacuum chamber. If so, I recommend you get it rebuilt, as it can be difficult to keep the master cylinder topped off. | | | | | Joined: Sep 2006 Posts: 1,997 Big Bolt Forum Co-moderator | | Big Bolt Forum Co-moderator Joined: Sep 2006 Posts: 1,997 | Lightholder's Dad, I'll check that tomorrow.
A day without laughter is a day wasted- Charlie Chaplin
When wrestling a grizzly bear, you have to keep at it until the bear gets tired, not when you get tired. 1948 Chevy 2-Ton | | | | | Joined: Feb 2007 Posts: 33 Apprentice | | Apprentice Joined: Feb 2007 Posts: 33 | Good news about your brakes. Moisture reduction is the key. With a fresh can of your dot3 you can accomplish alot with a clean syringe or turkey baster. Remove the fluid from the master reservoir and refill it. Drive for awhile and repeat the step. Doing this several times will clean your system and get you closer to pure and fresh dot3. | | |
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