Live in Peru, bought my truck new. Have a 1998 2500 12v Cummins, 4x4, manual trans, 202K miles. Somehow the brakes work fine yet the brake fluid level continually drops to the point of emptying the deposit. But there are no visible leaks anywhere....... Any ideas?

 

Pull your drums and see if your wheel cylinders are leaking. Otherwise, it's going somewhere. Between the gas tank and frame is a common place for the brake lines to rust out. Or it's leaking into the booster, but I imagine it should be appearing somewhere.

 

Thank you for your input. No, there are no leaks by the wheels/hubs nor over the fuel tank (just had it out for cleaning). You mean some sort of internal leaking? Where is the fluid going? I must have re-filled the deposit 3 times in the last 6 weeks.....

 

The brake fluid is going somewhere. If you cannot see it leaking at the master/booster, and you don't see it along the lines, where is it going? Pull your drums off and check for leaks inside. If not there, it's got to be going out the back of the master - into the booster, down the firewall, or inside the truck.