Ural 4320 brake problem- brakes on

[Abrs]

Thing is if it is the valve that's stuck it'll most likely be for one of two reasons, either the seal has become degraded and bonded itself outer part of the assembly, in which case a lubricant/solvent might work to free it up for now, or there is some corrosion present, in either instance it's probably safe to assume the assembly will want replacing before the truck goes on road. It is possible there is some contaminant causing it to stick open but not likely, the system is of course fed by the compressor on the engine, the only substance likely to be found in the system is small quantities of engine oil that has entered past the compressor piston rings, this is actually beneficial as it helps to keep things lubricated and acts as an anti-corrosive, which is why it's always important to drain the air down at the end of the day, as this helps remove some of the moisture that builds up as the air is compressed.

[paulob1]

yes it has a good write up AC90...slightly more sticky than wd40 so not sure how that would go in the air system...