Location: Near Toronto, ON
Posts: 1,211
My VIN: Previous Owner of 5875
Club(s): (DOI)
My car is currently up on a rack getting new coolant hoses installed. After removing the fuel tank cover, it's been discovered that something has eaten away the epoxy on the hidden side of the cover. It's all bubbled and eaten away. Has anyone else experienced this? I'm thinking the master cylinder is leaking, but I didn't have time to really look into it. Would this diagnosis make sense?
Previous Owner of 5875 - 1981/Grey/5-Speed/Grooved Hood
Location: Purmerend, Netherlands
Posts: 747
My VIN: 06513
Club(s): (DCN)
Don't start thinking of the worst possible.Originally Posted by pezzonovante88
A PO or his service shop may have been spilling fluid while changing or filling up.
That happened on my car too.
If the bottom of the brake main cylinder is dry, suspect spilling.
Welmoed
Black D 1981-11 sold
Toyota Prius III 2009-07 (sold)
Mazda MX-30 (BEV) 2020-09
Location: Stevens Point,WI
Posts: 2,471
My VIN: 6125
My car had both clutch and brake master leaks at one point in time and the brake fluid dripped down the side of the frame and pooled on the fuel tank closing plate. I discovered it far too late and the epoxy was shot in a pretty large area and the steel started to rust.
The most important thing is figuring out where the brake fluid came from. If something is indeed leaking it should be pretty obvious. Check for wetness on the brake master and servo/booster, and check your clutch reservoir line to see if it's in good condition. As the hose that connects the reservoir to the clutch master cyl ages the hose will 'sweat' and eventually start leaking.
Or as Welmoed noted, someone could have done a poor job of topping off the fluids and spilled some brake fluid.
I suffered some epoxy damage on the frame too. This pic is after some cleanup and rust removal
Last edited by Mark D; 05-08-2013 at 04:30 PM.
Location: Northern NJ
Posts: 8,582
My VIN: 10757 1st place Concourse 1998
If you are not losing fluid, ie, the level is not going down and you have to add brake fluid, this damage could be from an old leak and the cylinder was replaced already. If you do not see any brake fluid and you aren't leaking any, just remove all of the loose epoxy and repaint the frame and plate.
David Teitelbaum
Location: Sacramento-ish
Posts: 4,408
My VIN: 02100
Club(s): (NCDMC) (DCUK)
It's so funny how all these cars have the same exact issues. On mine the only spot of rust the whole frame long is right in this exact spot, and it was clearly from an old leaking master as the vacuum booster has drip damage on it as well (under the brand new shiny master). One day I'll get around to cleaning this up too!
Jon
1981 DMC-12 #02100. July 1981. 5-speed, black, grooved w/flap.
restoration log, March 2011 to present
full and detailed photo restoration log
Posts: 6
Spent some time under the car today. Discovered the brake leak same way, dropped the gas tank to clean, saw the destruction below. On mine it appears to be a resivoir leak. Res sits inside of 2 rubber grommets in the master. Only evident current leaking seems to have come from the front one of these. Res. slid in and out of the grommets much too easily for my taste. Just startin to research if and how these are replaceable, or does it require a new MC. Meantime- tommorrow its under the car again, this time with a putty knife to scrap off the bubbled frame paint. Anybody replaced these grommets before, and are they even avail.?---- Thanks.
Location: Northern NJ
Posts: 8,582
My VIN: 10757 1st place Concourse 1998
Rare for them to fail, they usually leak because they got damaged during installation. They can be replaced without replacing the master if you can get just the seals.
David Teitelbaum
Posts: 6
Only visible leakage was from below the res. at the front grommet. Resivoir pulled out much too easy, Should have been at least a bit of resistance. Car has been sitting inside garage for a long time. South Texas sun gets temps well over 100 almost every day in the summer in the garage. Guessing-- hoping, they shrunk or hardened from the climate. As I said drip pattern was directly under, any dampness remaining was right under the res. Now to try to find the replacements-- no luck so far.
Location: Stevens Point,WI
Posts: 2,471
My VIN: 6125
DeLorTex, I've got two reservoir seals that I could remove from my old brake master and ship to you. I bought one of the new units from DMCH so my original master cyl is sitting on a shelf. I can't promise their condition is in much better shape than yours though. The master itself was pretty rusty and pitted inside which is why I replaced it. It didn't appear to be leaking from the connection points to the reservoir though. If you're interested the seals are yours at no charge.
Otherwise I always seem to have luck calling DMCMW for parts like this that aren't normally sold separately.
Last edited by Mark D; 05-09-2013 at 01:04 PM.
Location: Parker, TX
Posts: 731
My VIN: #1283
Club(s): (SCDC) (DCUK)
This is so commonplace that the question should almost be "has anyone NOT experienced this?" I had my fair share of it from a PO but it's been cleaned up since. Last month when I did a brake job, every drop I spilled tried to find its way back to this very spot...
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