99 FG Brake fluid leak

[kerry]

Dealer installed the used tank today and it seems to be holding fluid. But when test driving it to resolve the pulling problem they determined the front brakes weren't working right. They couldn't lock them up. They did more bleeding and the service manager told me the mechanic discovered there was a proportioning valve which split the braking pressure between the two front wheels. It needed to be bled and they think they have all the problems resolved but want to let the tank sit overnight to make sure the tank is not leaking. So, my question is, can anyone confirm there is a proportioning valve between the front wheels? Part of the ABS?

I thought when I first got the truck back after they replaced the front brakes because the front cylinders were seized up, that the front brakes did not seem to be functioning well. Were the cylinders seized because they weren't being properly activated by the system? I know people complain about inadequate braking on these trucks.

 

[kerry]

Got the truck back from the dealer and it seems to be braking in a straight line and no leaks from the reservoir. I'm attaching some pictures of the reservoir so you can see both how it is attached under the dash (two screws accessible from the filling hatch in the dash) and the source of the leak--the rubber plug which holds the level sensor wires. I had planned to removed the plug, pull out the sensor and plastic weld the hole shut so I can use it for a spare. But closer inspection reveals the top of the level sensor inside the tank is considerable larger than the hole which holds the rubber plug. They must have installed the sensor from the top before welding on the top portion of the tank with the fill hole. Since the fill hole itself is not just an open space, there's no easy way to remove the sensor assembly. I'll have to give it some thought. A person could probably retrofit a generic small reservoir tank in place of the OE tank with some effort. It does need three hoses. I assume two for the brake master cylinder and one for the clutch.

 

[kerry]

Ok, maybe have a solution. Cut the wires off and plastic weld the lid off a soda or water bottle over the top of the rubber plug.

 

[SkiFreak]

Have you identified exactly where the leak is?
Is it all around the rubber grommet, a specific spot on the grommet or around the wire?
I would have thought that if you cleaned the leak area thoroughly with a solvent then you may be able to use a suitable adhesive to seal the leak. Something like Sika 252 maybe?

Not having the tank in front of me I can only go by your photos, but if you were to push the rubber grommet into the tank, could you then reseat it back into the hole? If you can do that then you could clean all around the grommet and hole with a solvent then use a suitable glue to secure it back in place.
I am pretty sure there would be a suitable 3M cyanoacrylate glue that would adhere to both the rubber and the plastic. Something like Scotch-Weld PR40 maybe, which is specifically designed for bonding plastics and rubber.

Just my 2c worth...

 

[kerry]

The shop did the analysis both while the tank was in the truck and on the bench and said it was leaking around that grommet. Not sure exactly where. The shop was convinced that no glue or resin would seal it. I'm not familiar with the glues you mention but I think plastic welding would do the trick. I have a plastic welder. The mouth of the tank has a plate across the bottom so if I pushed the sensor in, I wouldn't have enough access to reset it in the hole. I'm pretty sure the sensor was installed before the top and bottom of the tank were welded together. It's a poor design. Perhaps it was superceded by another design and that's why this tank/sensor is NLA. Has anyone looked at a recent FG manual brake fluid reservoir? Is it like this or different?

 

[SkiFreak]

I just took a look at my truck (2010 FG84) and the tank design is definitely different from yours.
It still has three fluid outlets and the rubber grommet for the sensor wires in the base, but the position of the outlets is different, as are the mounting brackets, which on mine are at the bottom.

 

[kerry]

Thanks. So newer model tanks are unlikely to fit a 99. I'm looking for a good sized bottle cap to weld over the grommet.

 

[kerry]

Got around to welding up the old tank. Water bottle cap was too big. Too close to the center outlet tube so I settled on a toothpaste tube cap. Not a pretty weld but leakproof. Had some trouble using the hot air welder so I used my old soldering iron type welder to finish the job. It's not leaking now.

 

[kerry]

This is the plastic welder I ended up using. I like the 'push the rod thru' option. Don't see them for sale anymore but Harbor Freight as a similar model witout the push thru feature.