Front master cylinder leak

[PA Chopper]

Hey guys,
I've searched the forums and didn't find much about this. I do see that it happens to others though. My front master cylinder leaks fluid around the cover. Fluid is coming out between the cover and gasket. Everything looks fine with the gasket and the cover seems flat but then fluid is coming out to cover the entire master cylinder. I even had it fly back on to my jacket sleeve yesterday and had it drip on to my rocker box cover once I parked. I got lever still but if it keeps leaking I may end up with no brakes while I'm riding it. Whats you fellas think?

Dan

 

[lee]

if its leaking that bad you need to nail down exactly what the problem is and get it sorted. I know you already know that,

 

[jsub]

It not overfilled is it?

 

[PA Chopper]

It not overfilled is it?

I don't believe so...but it could have been. It lost enough to make a hell of a mess so the level should be down now. I still have a good lever so maybe it pushed out the excess. I plan on cutting out of worl early and riding so I'll see if it keeps leaking. I talked with my dealer and he says sometimes the chrome on the lid can cause an edge that prevents it from sealing. I sanded down the underneath and removed some off the edge but it still leaked this morning. :angry:

 

[07bigdog]

I had a slight sweat from mine after i took the cover off to check the fluid level. Once i wiped it off after riding it was okay. Make sure and torque down the bolts evenly. You don't want to get brake fluid blowing onto your paint, never mind just loosing your brakes. I also had problems getting air in the system. Last year in Sturgis a lost my front brake. I finally got all the air out of the system when i got back home. Has been good since.

 

[Gas Man]

Mine use to leak ever slightly around the bolts. But you can order a rebuild kit and it will come with the lid gasket. The rebuild is cheap.

 

[RAW Blue Rider]

I know!!


See The attached (I hope) BigDog Service Bulletin!

Happy Motoring!

RAW

 

[mrthick71]

I have an 07 mastiff that keeps leaking as well. I thought it was coming from the lid too, but upon further investigations, I found out later that it was really coming from the plunger itself. The wind blows the fluid up through the mirror mount and all over the top of the cover. I did the rebuild thing and it worked for about a week. My dealer said sometimes the aluminum housing gets out of round and it just needs to be replaced. Very conveniently for Big Dog I was just out of warranty when I started having the problem. I guess I have no choice but to fork over some major ching for a new set of controls. I wonder if the chrome ones are any tougher?

 

[Ridgeback05]

Check and see if the rubber gasket is torn

 

[PA Chopper]

Thanks for all the sugestions. I'm going to take the cover off again and clean the gasket real good and check for tears or holes. Wipe up and dry all the fluid around the reservoir, cover and bolts and put it back together and go from there. It's a brand new bike so I would hope the master cylinder wouldn't need rebuilt already. Always the possibilty that something is out of whack though. Thanks again.

 

[Trainguy]

My 08 K-9 did the same thing.:bang: Lower the level in the reservoir to about 2/3 full and as a added measure i put small fiber washers on the two hold down screws. No more leak :2thumbs:


RAW Blue Rider Good catch

 

[whatever01]

I don't believe so...but it could have been. It lost enough to make a hell of a mess so the level should be down now. I still have a good lever so maybe it pushed out the excess. I plan on cutting out of worl early and riding so I'll see if it keeps leaking. I talked with my dealer and he says sometimes the chrome on the lid can cause an edge that prevents it from sealing. I sanded down the underneath and removed some off the edge but it still leaked this morning. :angry:

Sounds like your dealer may be Full House Cycle....

 

[Analog]

Cylinder Leak

Dan
I have had the same problem with my 08 K-9. I have replaced the cover gasket multiple times, checked the chrome for bad areas, well not over full, made sure gasket is seated correctly, hardware tighted down correctly, and still every once and awhile I will see an oil streak running up the outer chrome housing. It's very agravating!! :angry: I have talked with the dealer, Full House, and all they can say is, "bring it in and we will have to look at it". Just when I think I have it under control, it will sweat again on me. I know you have to be very carfull to wipe out around the sealing edge of the cover gasket. Oil will lay in there you can't see and will wick out between the cover and base running down the road. I juat had 4k worth of paint done on my tank so I have my eye on that sucker all the time. I carry a rag with me just in case and when it's parked I have a heavy paper towel clipped around the cylinder just in case! Don't want my paint messed up because of a drop of brake fluid. I will be keeping my eye on this thread for other information and ideas. I'm about at the end of my rope on this one. :bang:

 

[07bigdog]

The Dot 5 brake fluid is not supposed to harm the paint, but i would still be careful.

 

[Beerdrinkinhellraiser]

Has anyone tried a thin rubber flat gasket, cut to fit?

 

[07bigdog]

I just use the stock gasket.

 

[rasdes]

Mine also leaked, I cut a flat thin gasket, oil resistant material, the same size as the top cover and placed it on top of the regular gasket, the extra pressure when tightenibg the screws will caused it to push the rubber seal deeper and tighter into the groove...this stopped my leak. The kit was -/+ 76.00 if I remember, all I needed out of the kit was the gasket....after doing this I canceled my order for the kit. Someone else on this forum previously suggested the same thing...this is not my original idea but I tried it and it worked!!

 

[GDOG_PITBULL]

I had to deal with this on the Pitbull but it was a leaking piston. Rebuild kit worked for a while then the problem returned. Cylinder wall felt smooth but who knows. Had a guy at the local shop tell me the rebuild works about 50% of the time. Not sure what the issue is and maybe I did something wrong on the installation. Worst case is pick up another MC off Ebay.
G