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brake resevoir overflow

4 May 2005
Has anyone ever experienced the leakage of brake fluid from the resevoir
-seems to be overflowing and there are no lights indicating a problem and no other side effects such as soft pedal or tcs or antilock issues. There is a big puddle under the NSX and it keeps coming - but the resevoir still full
....92 NSX 153000 km ...any ideas
Are you sure that it's brake fluid? Sounds like condensed water from the A/C. If it is really brake fluid the only explanation would be water in the fluid but that leads usualy to lower boiling point and all side effects like spongy brake pedal feeling etc... :confused:
yep, definitely brake fluid leaking all over the valve block - can see a possible pin hole in the resevoir top plastic - but does it run under pressure in there so that the fluid would be forced out thru it? - I thought the cap vents to atmospheric pressure - and why is the level not going down? - I have lost a good half pint a least now and it still shows full to the top
Maybe a stupid question, but is there any possibility that it is the reservoir for the clutch fluid leaking? They use the same fluid.
I seem to remember LarryB saying this was the classic symptom of a stuck ABS solenoid. Go out and exercise it. You can probably find more info with a search using ABS reservoir.
rbirling said:
I seem to remember LarryB saying this was the classic symptom of a stuck ABS solenoid. Go out and exercise it. You can probably find more info with a search using ABS reservoir.

I recently had this problem too. Brake fluid leaking all over my garage floor but my reservoir was still full. I waited for a rainy day, "exercised" the ABS and the problem went away. I also had to refill some brake fluid in the ABS reservoir. :wink:
I have the same problem when i first bougth my car,when ever i brake on un even surface the brake comes up. i did know at first, it happen same place everytime i brake before stop light . so i see puddle of brake fluid under my car in the morning ,hose brake fluid. And now anti lock light and pump up some time goes out in few minutes, sometimes it take awhile.A service manager told me to flush the system because piston binds in abs,or just go drive on empty parking lot and lock your brake while turning and free the piston.I wish this give you some idea. :biggrin:
Hi, I had this problem today where the abs is making noise and a lot of brake fluid came/leak off from the top of the abs reservoir cap, what do you guys mean by "exercise" the brake when it's raining?

what are the steps I should do do "exercise" when raining? thanks for your help.
"Exercise" means to drive in a way to engage the ABS to free-up a potentially stuck abs piston. Since our cars have great traction - and many of us avoid rain and snow, the ABS is seldom if ever used. So, to engage the ABS [one or more tires without traction under braking] , some like braking in rain [ reduced traction] - snow will do it to - gravel/dirt roads will do it, or driving on uneven surfaces, like two tires off the pavement - and you do not need to do it fast - 20-25 mph should be fine. And jam on the brakes, the idea is to lock up - and you'll hear the ABS kick in [ and feel it in your foot ].
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Never fill to the fill line. Just above min is fine. Remember, the accumulator has fluid in it an is under high pressure. The old ABS system tends to foam the brake fluid and then overflow.. If you have a stuck solenoid, it will continue to foam even more. Get that stuck solenoid free, change/flush out your fluid and it will be much better. Don't fill the reservoir.
If it is a 91 or 92, I offer all the o-rings and grease to rebuild the modulator, but remember, you need to get the solenoid un-stuck.

PS>> this is a 10 year old posting.
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that link is invalid Larry. Thanks for your help. As I reset the fuse, I stopped hearing the abs noise and back to normal. I also filled up the dot 3 fluid. Hopefully it will go away as I have to wait another 2 weeks or so in order to "exercise" in the rain, as the weather is sunny for the next week or so in SoCal :(.