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brake fluid in fuel lines...
The no-pressure gravity feed lines from the brake reservoir to the master cylinders weep brake fluid.
Wouldn't call it a LEAK, never add fluid, but the lines are wet and slippery...its not moisture. The original lines are SAE spec 30R6KX. Three are original lines, about 7 years old and on one of the brake master cylinders about 3 years old. Doing a lot of r&r for other odds and ends, thought I would change out the lines, but only if the new hose will not WEEP through the wall. OK, is there a SAE spec fuel line that is less permeable to brake fluid? I have some replacement hose, labeled SAE 30R7. One piece is labeled "fuel vapor" "not for fuel injection systems" the other SAE 30R7 and is labeled "50 PSI Fuel/Emission". OK, I guess both new pieces meet the SAE 30R7 spec as labeled, ie: they are good to 50 psi with gas, but what SAE spec line may be more resistant to having brake fluid weep through the side? Thanks |
Fuel resistance has nothing to do with resistance to brake fluid. Here's an example of a hose designed to handle brake fluid. I'm sure there are others.
http://www.pegasusautoracing.com/pro...p?Product=3260 |
After doing a lot of reading about rubber hose that is OK for brake fluid i settled on regular old rubber air hose. I forget the type of rubber liner that it has but it was cheap and the expensive SS braided fuel hose I wanted to use was not as good- the brake fluid would break it down and it would weep. My hose is red on the outside to match the car.
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The Teflon (PTFE) inner hose IS impervious to brake fluid but its inner (-4) diameter is 1/4" not large enough unless you are able to convert to male/female AN fittings.
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thanks
Guys,
I have hard steel or steel/braid lines on all hydraulic lines that are pressurized. The NO pressure lines from the brake reservoir are the concern. The brake reservoir is a BMW plastic piece with three outlets to the clutch master and the front/rear masters. There is no way to run braided steel ptfe? teflon core? type lines unless I switch to the "original type" metal canisters. Will take a look at the Pegasus catalogue. They have a lot of good stuff. I just want a easy change of material to a rubber type hose that is less likely to weep than the 30R6KX type. Again, there is no pressure, I just don't want the lines weeping fluid...no dripping they are just wet on the surface. Brake fluid is pretty unique/devious ! stuff...I think it was originally developed as paint remover... I am familiar with a red rubber type line I usually think of for air compresors. Thanks, Pete |
Pete I understand exactly what you are up against. If you want to retain the fuel "type" 3/8" hose you might look at the Gates or Goodyear hose website and then visit a rubber or hose distributor in your are. The fuel injection hose has much more reinforcement and cording to make it withstand the pressures common for fuel injection applications, the rubber may be a little different too?
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Rick,
I am guessing that the difference between brake fluid and gas surface tension? is the issue, not the pressure involved. In this case, other than gravity, there is no head of pressure. That said, at a HIGHER pressure fuel injection gas line would need to be more impermeable to GASOLINE, but I am guessing that brake fluid is a different animal. Could be the ticket, lets look into that! I was thinking about something like "TYGON" clear plastic tubing, but it may be too stiff compared to rubber type line. In another day or so I will button this thing up, and use what I have. Worst case it weeps... Thanks again to all |
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