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Contributor
Location: Prescott, AZ | Been fairly quiet in this corner so thought I would bring up a discussion I haven't seen in here and didn't see it in Yahoo either. The pitfalls/danger of DOT 5 and the Hydro Vac system if there is a failure and fluid leaks back into engine (small annoyances to major problems). My neighbor, who has 4 antique trucks, mentioned this to me a few months back. He says it is why he won't use DOT 5. I have since searched the interwebs and have found quite a few discussions on various old car/truck forums. So is it not a concern with FMC systems? Very rare chance of it happening? Anyone heard this before? Just asking... |
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Veteran
Location: Canton, (Sixes) GA | Mighty 890 has had DOT-5 for eight years and over 35,000 miles with zero issues. About everything was replaced and the system flushed with alcohol at that time. The infamous MCR drum brake upgrade. A couple of years ago I pretty much flushed the system and replaced the DOT-5 again when bleeding (and bleeding, and bleeding) to get a decent pedal. Next project is replacing the hydravac's, suspect a rear ruptured diaphragm. I did Google DOT-5 issues and found several. Over the years I have considering converting my 71 Malibu and 93 deVille to DOT-5, doubt I will now since I'm not going to replace the master and wheel cylinders, will just stay with DOT-3 on my classics. I do need to at least bleed them both. Hope we get some chatter on this subject. DOT on...
Edited by denshew 2015-06-01 8:19 PM
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Extreme Veteran
Location: Ignacio Colorado | I went with a friend to pick up an old international truck he was buying. The seller was trying to get the brakes to work, adding fluid and pumping the pedal ect. We are standing by the truck checking it out when all of a sudden the thing starts to blow bluish smoke out the exhaust. Big cloud. My friend did buy the truck and limped it to his mom's house close by. I had him pull the booster and I took it home. It was full of dot 3. I pulled the booster apart and cleaned everything up. It did not appear to be rusted or pitted and the seals looked intact. Bunch of crud in it but the pieces were intact. Cleaned it out and assembled with dot 3. It went back on the truck and has not been an issue since as far as I know.
No idea how it affects the engine but you would have to go through about 1-2 gallons of dot 5 before you have enough fluid in the booster to have it try to get to the engine. Please tell me that a gallon consumption would light a bulb that says you have a problem. Oh it does, that red one in the middle if the cluster that says BRAKE. I think I would be more concerned about the damage dot 3 could cause than dot 5 but I missed out on chemistry class.
Now Denny, can you install a vacuum gauge inline with your booster and have someone step on and hold the pedal while you watch the gauge. It will drop when the pedal is pushed but should regain the vacuum reading you had to start in a few seconds. If you have a ruptured diaphragm the gauge should drop and stay low with the brake applied. Denny has a diesel engine and a vacuum pump. No need to worry about engine damage running a diesel as an external vacuum pump is used. Bill |
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Contributor
Location: Prescott, AZ | Well your experience seems to be the norm, tons of miles- no issues. I can't determine if the cautions that I hear and read are from real problems that people have experienced or just 'alarmists' who are freaked out by the thought of silicone fluid getting in their engine. It just doesn't burn off.
denshew - 2015-06-01 8:16 PM
Mighty 890 has had DOT-5 for eight years and over 35,000 miles with zero issues. About everything was replaced and the system flushed with alcohol at that time. The infamous MCR drum brake upgrade. A couple of years ago I pretty much flushed the system and replaced the DOT-5 again when bleeding (and bleeding, and bleeding) to get a decent pedal. Next project is replacing the hydravac's, suspect a rear ruptured diaphragm. I did Google DOT-5 issues and found several. Over the years I have considering converting my 71 Malibu and 93 deVille to DOT-5, doubt I will now since I'm not going to replace the master and wheel cylinders, will just stay with DOT-3 on my classics. I do need to at least bleed them both. Hope we get some chatter on this subject. DOT on... |
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DOT 5 and Hydrovac
