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Brake fluid overflow....anyone experienced this problem...
Three times now after getting the brake fluid flushed on 2 different 993s at two different shops I've had brake fluid backing up over the reservoir lip and dripping out of the drain hole in the frunk after driving home. It's happened two times in a row on my 1997 turbo and just recently on my 1997 c4 cab. The second time on the turbo the dealer looked at the car and said the problem was a malfunctioning brake booster that needed replaced for $3k. Now I'm wondering if there really isn't anything wrong with either car but mechanic/technician error? It all seems too coincidental. Each time this happens it's a godaweful mess to clean up. Does anyone have thoughts? Is this a chronic problem/known problem?
You have to make sure you fill when car is on so the pump is running. I think the reservoir is easy to overfill a bit. I had this happen to me couple of times where some sipped back, I leave a crumbled paper towel on top of the reservoir around the cap to absorb any overflow.
Next time maybe don't fill it quite as full.
I seem to remember there is a place for an overflow drain tube to be attached to the top of the reservoir. It is usually capped and not used. To avoid the consequences of overfill in the future one could always remove the cap, replace it with a hose, and route hose out one of the drain grommets in the bottom of the frunk..
Yes - mine has an overflow drain tube connected and it overflowed the first time I did it because I didn't have the car running and the booster pump wasn't on.
You have to make sure you fill when car is on so the pump is running. I think the reservoir is easy to overfill a bit. I had this happen to me couple of times where some sipped back, I leave a crumbled paper towel on top of the reservoir around the cap to absorb any overflow.
Ahhh....okay thanks for the input. I don't see anything there that could be an overflow drain. But could it be possible that the technicians didn't have the car running when they refilled the brake fluid? I don't change my own brake fluid so I wouldn't know. Is this something that isn't done on most other cars? Could it couldn't be that simple? NY993...this is no mess that a crumpled paper towel can absorb. My guess....8-12 ounces overflow at least.
I'm very sensitive to this brake fluid thing now because the second time it happened with my turbo...brought the car home...parked it on a lift...pulled another car underneath and left town for a week. When I got back I had to repaint the hood, fender, and bumper of the car underneath the leaking fluid/993. Dealer said it wasn't their fault even though they'd been told it happened the previous time they changed the fluid. Blamed it on the brake booster and a malfunctioning car....
The overflow hose/venting hose has been omitted as from October 1995.
The Porsche Maintenance manual for changing the brake fluid for cars (Turbo, C4S and C4) with hydraulic brake booster calls for a second step in the procedure after bleeding at the wheels. It says to drain 200 cc brake fluid at the pressure accumulator.
Wonder if they aren't doing that and that is where the extra brake fluid is coming from?
the reservoir is stamped with instructions to 'fill level with charged accumulator.'
the 'max' line is hard to see and there is a ton of space above the max fill line that somebody might feel the need to fill.
if the car has been sitting for a few hours, check the fluid level, then turn the ignition key, don't bother to start the car.
the pump should start and you can watch the fluid level decrease as the accumulator is pressurized.
after sitting for a while the pressure will be released and the fluid will flow back into the reservoir.
what might be happening is the shop is filling the fluid to above the max fill line while the accumulator is pressurized.
they might just fill the reservoir to the top because that is where the max fill line is on many cars.
the problem doesn't show up until after you are home and the car has been parked long enough for the pressure to be released.
then the fluid flows back into the reservoir and overflows.
all that space above the max fill line is supposed to accommodate somebody filling the fluid to the max fill line while the accumulator is charged.
but there isn't any need to be much over the min fill line while the accumulator is charged.
then when the pressure is released the level will rise to the max fill line.
here's a pic of what I'm pointing out, the carrera reservoir max fill line is almost at the top.
some idiot even overfilled this carrera reservoir, but no overflow or spillage.
this is a pic of your turbo reservoir
the max fill line is a solid 20mm below the top of the reservoir.
if someone were to fill up that space(as above) with the accumulator pressurized it would overflow after the car has been parked long enough for the pressure to be released.
so kind of an easy mistake to make by an inattentive shop monkey.
I'm not suggesting you go easy on the shop, they messed up and should pay for the paint damage and refund what they charged for the brake bleed.
you should also never go there again after being told to spend 3 grand on a pump that doesn't need replacing.
Great description! I hope it is something that simple. The first 2 times occurred at the Porsche dealership with my turbo and they insist (at the time) they did nothing wrong and followed the procedure. Last week the most recent time the overflow happened at my independent shop on the c4. I just can't believe they are all making the same mistake on such a routine service! But it sure does seem suspicious. I'm afraid it's been almost 2 years since I've had the fluid changed in the turbo and the head Porsche mechanic has since left; the same service manager is still there though. I'm going to the independent shop tomorrow on my way home...they are very forthcoming and I've known them for 15 years. If a mistake wa made they'll let me know what happened. I'll fill you guys in on what happened....
06-20-2017, 03:21 AM
Brake fluid overflow....anyone experienced this problem...
