3-Series (E21, E30)Chat relating to the BMW 3-Series from 1975-1983 and 1984-1991 line. Specific models: BMW 315, BMW 316, BMW 318, BMW 318i, BMW 320/4, BMW 320i, BMW 320/6, BMW 323i, BMW 320i. E30 Family models include: BMW 325e, BMW 325i, BMW 325is, BMW 325ix.
My duaghters car, an 87 325 with ABS has developed a taste for DOT 4.
About every two weeks of so the low brake fluid light comes on and demands a shot of juice. There are no visible leakages at the wheels or under the car and no tell-tale smoke. The little car still stops on a dime! Pad and rotors ( 4 wheel disc) are nealy new.
I really proud of my 25 year old daughter/student living in Savannah georgia. (pictured in my 325ic below) Last week her 325 overheated and had to have a new thermostat. Taking Dad's advice, see aquired the parts, bought a small set of hand tools and did the job herself! The offending thermostat now hangs from her rear view mirror. She recommends the use of neo sporin to lube the new thermostat o-ring!!!
Ok, 2 things here. First, I suspect the brake master or clutch master cylinder is leaking into the car by where the pedals are. Take a feel aginst the firewall and see if it feels damp or you hands smell like brake fluild after pressing on the carpet. If it does take out the lower kick panel and pull the carpet back to see which one is leaking. Another posibality is the clutch slave cylinder leaking into the bellhousing.
Second, the thermostat o-ring on the M20 does not need to be lubricated but if for some reason you feel the need to put something on it use silicone paste, nothing else otherwise you run the risk of contanimating the rubber and having it swell up and leak. Any rubber o-ring or seal that you feel the need to lubricate should be lubricated with something silicone based. Petrolium baised lubricants will damage rubber causing them to get soft and weak which will lead to premature failure. Do an experment sometime, get two identical rubber o-rings. Lubricate one with regular white grease, the other in something silicone based. Let them sit for a couple days and go back and look at what happend to the one with the petrlium based lubricant on it.
I can say for sure that there are no leaks from the clutch or master cylinder. Just had the carpet up for cleaning. As to the effects of
vasoline on rubber, you are of course correct, however there are no petrolium based compounds in neo sporin ointment. I'ts chemicaly inert. The only reason she put a compound on the gasket was to help retain it during assembly. It kept falling out. Anyway, Dad can always fix any leaks that develop around the thermostat. Still I'm puzzled...perhaps a internal leak in the power brake booster?
I'll check the slave cylinder...good thought!
It could be leaking into the booster but I would think that it would seep out and leave a trail either down the front of the booster or down the firewall. I know there is no petrolium in neosporin, otherwise I doubt it would work as an ointment. I was just making a statement because a lot of people don't know you shouldn't put petrolium baised products on rubber.
A power brake booster can hold up to a half quart of fluid before it'll leak. But the brakes would feel hard. I'd check the ABS unit, if it leaks the fluid could run into the frame chanel and get soaked up by the dirt in there.
Hello my name is Chuck, I work for a independent BMW service and repair shop in the west ATL. area. On the early E30 cars I have found that they like to leak brake fluid from the brake proportioning valve under the brake master. I am quite sure you can not see this part from the top side of the car but if you get under it and look below the booster you will notice a small brake distribution block which will leak fluid all over the frame and take most of the paint off if not addressed. This is usually the cause of the disappearing brake fluid.
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