I had a 310L come to me pouring hydgard out the bell housing. Assumed it was the front pump seal. Pulled trans replaced front seal although no damage found chewed up o ring under plug in bell housing with a piston behind it. What I’m assuming is a pressure relief valve or some sort. I also replaced o ring on pump. After reinstalling trans. I can’t get the parking brake to release. I have no fluid pressure in the line that goes to the parking break drum. Ive tested the solenoid itself its working properly I don’t think I’ve crossed any lines as they are all different sizes. Any one got any ideas maybe a plumbing diagram for the hoses.
Welcome to HEF Jason ! Serial number? Did it move before the repair? Does the PB release if you rev the engine up? Unfortunately the most likely reason for the leak would have been a bushing issue within the trans charge pump. Did you give that a good look? Was the nose of the torque converter scored? Did you check any pressures? Look into the transmission filter to see if it is coming apart? Cut open the transmission filter to look for debris?
Yes, I replaced the pump with a new one as one of the ears where the torque converter lip sat was cracked. Replaced torque converter and replaced filter with a brand new ZF oem filter. Also should note that after replacing charge pump it would blow the filter o rings. And yes I drove I released the brake and drove it in the shop lost a couple gallons of oil in less than a minute the leak was so bad but it released and drove prior to repair. I didn’t check actual pressure but I cracked filter at housing to check for pressure plenty of pressure there I also removed the park brake solenoid and have plenty of fluid there. Just none coming out of the port that goes to the drum to release the brakes. Also the two individual foot brakes work fine
That is why the system pressure needs to be checked with a gauge. If it drove into the shop and now it won't move it begs the question: what changed? Serial number?
new pump new torque converter and I had to tear transmission down to remove charge pump to replace. Where do I check the pressure and what should it be. I’ll get the SN in the morning.
Spec is 290-305 psi with the engine @ 2000 rpm and the oil temp @ 167-185*F. I will double check that once I have a serial.
Talk about different. Comparing this transmission to my 310E transmission is crazy. I don't even see how pressure is controlled here?
This is the exact transmission I’m working with. After checking pressure with guage by removing the plugs he posted I had over 700lbs at operating temp of 126f I manually tested the solenoid one more time with my power probe plunger opened just fine. After reinstalling solenoid i crunk machine and pushed parking break and miraculously had plenty of fluid in the line now. The solenoid must be going out.
From what I can tell. This is my first time in one of these now. But pressure seems to be controlled by a relief valve. Inside the trans if you look at the picture he posted it is almost directly behind the first arrow pointing down closest to the filter housing. There is a plug inside the bell housing in that upper corner. If you remove it there is a piston with a relief hole a spring and 2 shims. I believe it is regulated here. There was also a check ball that relieves pressure in the case.
The specs I gave are correct for that S/N. Looks like the trans is coming back out. Also inspect item # 6 for debris as well since it will be apart. Do you have the original filter yet to cut open?
So the root cause of this problem might be that the tinniest particle caused #5 (piston) to lock itself in a position that allowed unregulated pressure to blow out the o-ring OP found. So transmission has to be pulled and housing removed to access that valve/piston?
yeah that valve is inside the bell housing behind the bell housing cover actually.
Original filter was clean. Number 6 in that photo had a check ball in it that I don’t see listed in that photo. Tore everything down cleaned meticulously with solvent. Replaced pressure regulator assembly as well as parking brake solenoid. Still have too much pressure?
As far as I can tell the o ring #4 was blown which was the initial cause of the massive leak as it’s under pressure. However after taking care of the leak the other issues arose.
Jason, did you take that regulating valve apart and clean it? How many hours are on this machine? I suspect your original problem was the 700 psi. Not that it cropped up after you reassembled machine.
I agree. Do you have the old filter? Was it a black filter? I ask because those black filters have a habit of coming apart internally sending shrapnel into the system causing the relief valve to stick one way or the other. The black filter was a carry over from the ZF model that is in JL's machine to the model ZF that is in your machine as well as the "J" and "K"'s. Those older transmissions run at lower pressure and yours at a higher pressure. They discovered that the black filter can't handle the higher pressures so the change to the white ones. The white ZF filter is a heavier duty filter designed to handle higher pressures. I'm curious, was the bushing in your old transmission pump in place and completely grey in color? Any brass showing? Nose of the torque converter blemish free? Reason why, to doll out a little education, is those transmission pumps are another week spot on the serial number transmission you have. The PTFE coating was inadequate and the bushing moves towards the seal affecting it's ability to seal causing a leak. It can do this without any visible damage to the seal, however there is usually visible damage to the bushing and the torque converter. . Fortunately the new pump you bought has had the issue fixed.
The original filter was a car quest branded hydraulic made by clarcor. Bushing didn’t appear to have any brass showing. Torque converter was replaced so there was no damage to the nose of it. I replaced the filter with white ZF oem filter.