TA300 ... continually transferring hydraulic tank oil onto transmission. Replaced main pump. Any other locations where the oils can migrate from hyd to trans? I'm thinking DCV seals. Am I missing any other locations? TA30 ... road brake doesn't consistently apply when park brake is set, with engine running. Replaced treadle valve, park brake switch, and park brake solenoid. I'm also thinking DCV plunger sticking. Issue was exacerbated by worn out park brake pads (now fully repaired). DCV (Directional Control Valve) The other guy here, along with me, are running out of ideas. Any help would be greatly appreciated.
On a TA30 there should be two pumps. They are next to each other. Both have seals that keep oil out of the trans. Should have the other rebuild. We had that same issue on our TA30 and that fixed it. Good luck
This TA30 is closer to my TA300, only one hydraulic pump on the back of the transmission.
Maybe different for years. Ours had one for hydraulics and one for power steering function. Both driven by the trans. We also had a TA40, but I think both were the same.
Did you find a solution to your problem or is the problem still there?
Both are still an issue. TA30 doesn't always set road brakes, when park is activated, engine running. Park brake is 7 brakes holding with engine on. Park caliper only with engine off. This one doesn't always set the road brakes @ Engine on, Park engaged, like the other 5 here. As for the TA300, waiting on a DCV to try on it.
TA30 make sure that the transmission oil level is at the required level, because if the transmission oil level is lower than the required level, the DCV will remain closed because the 16 bars required to make it open will not open, and thus the park break will remain applied ، Transmission pressure must be constant 16 bar. At the same time,I advise you to check VALVE-PARK BRAKE This is the valve that the electric coil is mounted on,
When you start the engine, Where is it on the oil dipstick?
TA30 Parking caliper works as designed. Other tech here changed pressure switch, park solenoid and cartridge, and dashboard button. I repaired park caliper and resealed treadle valve. On my TA30 trucks, working properly, do the following. 1)Parked and off>park caliper holds. 2)Parked & started>foot brake applies as accumulator #2 becomes charged (All 7 brakes applied) 3)Parked brake knob pulled out>park caliper releases and foot pedal becomes operational. 4)Shutdown> all 7 brakes apply until Accumulator #2 bleeds down, then only park caliper holds. On this TA30, sometimes the road brakes apply when the park brake is set, other times, they don't apply. Sometimes they apply late. Park brake always releases when requested.
The problem you have starts from the oil line that comes out of the transmission and goes to the hydraulic valve on the TS port and then goes to the DCV As for the DCV, I advise you to change its seal kit first before changing it because it is not easy for it to break down.