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noticed a nice puddle of brake fluid on garage floor just behind drivers rear wheel. upon inspection,
reservoir was empty. at the bottom is a good deal of debris. took off resv and sprayed with brake
cleaner, but still a good deal of crud at the bottom
is there a "safe" chemical I can use to soak the reservoir in to get that stuff out? I have denatured alcohol,
lacquer thinner, acetone,..?? any suggestions?
pretty sure that the resv is not leaking, but not sure where it is leaking from. it could be from the hose
with the banjo fitting, leaking at the banjo? it appears to be coming from below the pressure accumulator,
and more towards the passenger side, below the pump.
is there a more "common" point of leak on these systems?
Never heard of these things leaking fluid before. As with anything that contains liquids and leaks there has to be a leak path and inspection should have suggested where it is coming from but if you have removed the reservoir then that has been compromised to some extent. Presumably the reservoir has a grommet problem and/or maybe a crack in the plastic? I understand those things are difficult or impossible to get hold of these days- doubtless Roger can shed some light on that one.
I have heard of these things having to be rebuilt and some chap in Germany does this apparently. I seem to remember a thread with a video link not that long ago not that you would want to do such.
The DOT 3 fluid is a PEG [polyethylene glycol] and as I understand it dissolves in alcohol- do not try to use gasoline or diesel to dissolve.
thank you fred.
to be clear, the reservoir does not appear to be the source of the leak. it may well be the banjo fitting
and/or corresponding hose. since it was empty, it must be at a lower point?
so from your perspective, there is not a "common" leak issue.
still wondering what might be the best fluid to soak the reservoir in
I've used brake kleen to clean some pretty nasty PSD reservoirs after removing the internal filter. Takes a lot of scrubbing and unless you split the reservoir at the seam you'll never get it completely clean due to how it is plumbed.
thank you fred.
to be clear, the reservoir does not appear to be the source of the leak. it may well be the banjo fitting
and/or corresponding hose. since it was empty, it must be at a lower point?
so from your perspective, there is not a "common" leak issue.
still wondering what might be the best fluid to soak the reservoir in
I've used brake kleen to clean some pretty nasty PSD reservoirs after removing the internal filter. Takes a lot of scrubbing and unless you split the reservoir at the seam you'll never get it completely clean due to how it is plumbed
kevin, can you let me know how to split the seam and how to remove the filter?? and
how to reseal properly
I always have White Spirit in the workshop
Ake, I have some mineral spirits, but I am not certain this is strong enough to
dissolve the debris?
I hope it does not come to this but we sell rebuilt PSD units.
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission? George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
I did not mean to imply I had split it, but you will note that the return route to the reservoir goes to a part of the reservoir that cannot be reached for easy cleaning. Having said that using a box cutter or similar tool you should be able to separate the reservoirs at the seam.
As for leaks - I would examine the place the motor and pump meet. There is rubber gasket/o-ring that separates them. And a good look at the supply and return hoses, too.
thank you fred.
to be clear, the reservoir does not appear to be the source of the leak. it may well be the banjo fitting
and/or corresponding hose. since it was empty, it must be at a lower point?
so from your perspective, there is not a "common" leak issue.
still wondering what might be the best fluid to soak the reservoir in
Without wishing to be alarmist my concern would be what that crud in the reservoir is signifying. Brake fluid is hygroscopic, i.e. it absorbs moisture from air and thus why brake systems and the PSD need to be flushed regularly [every two years ideally]. If this does not happen then corrosion sets in and presumably how the crud forms. When I flushed my PSD system a couple of years ago I was surprised at the condition of the liquid that was bled out of the slave cylinder and mine was changed previously. Did not see any crud in the bottom of my reservoir.
As for leaks - I would examine the place the motor and pump meet. There is rubber gasket/o-ring that separates them. And a good look at the supply and return hoses, too.
kevin, have you had a pump apart? my leak is either as you have mentioned, between pump and motor, or possibly
the plastic elbow for the lower hose on the reservoir. behind that is an O ring as well??
Paul, do remove the filter out of the reservoir and you can clean it properly
Ake, can't figure out how to do that...???? have sent PM
Brake fluid is water soluble. Don't use any cleaner that is oil based. Alcohol or just plain water works the best.
If the pump runs, fill up the reservoir, turn on the key, and allow the system to pressurize.
The most common leak is from the high pressure accumulator splitting a seam and spraying fluid out at very high pressures (they usually will not leak until the pressures are very high.)
Don't stick your fingers in there to "feel" for the leak.....there's enough pressure involved to cut your fingers right off (if you are lucky). If you are unlucky, the fluid gets injected under your skin. (In the military, they say this will kill you, before you can reach the hospital.)
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
06-04-2018, 07:27 AM
PSD reservoir overnight soak? PSD leak
George Layton March 2014
