50 Hr SVC can not get hydraulic pump to prime

[RJFEJF]

I just did my 1st 50 hr svc. changed external filter, drained all fluid and refilled to spec capacity and appears correct on dipstick on Transmission and Aux tank dipstick, breather is clean. This is a Foton/lovol TE354, 35HP/4WD, koyker 160 FEL, power steering, in addition to the 3pt lift. This is an open center system. The filter is at the lowest point and I cracked the line on both the tank side and pump side of the filter and clean oil seeps out both sides. I made sure all suction line clamps are tight. I can't seem to get the pump to suck the oil from the filter up about 1ft to the pump. I have run the tractor at idle, while periodicly operating the 3pt control for about 1/2hr at a time till when the pump warms up. Then I shut It down let her cool and try again. I have put about 2hrs on the tractor total attempting to get a prime to the pump,without getting any operation on the 3pt, fel, and steering. I listened to the pump using a screw driver, pump internals sound like they are spinning and nothing sounds broken. A svc tech said it must be seriously airlocked and if there is fluid at the lowest point between the filter and pump. All that can be done is let it run, operate 3pt and only 3pt till air is purged, then operate the fel and steering after the 3pt functions. Shutting down tractor when pump or hoses need to cool down. I asked if it would be ok to charge the aux tank fill port with about 5-10 psi of compressed air to lift the fluid to the pump, while all the controls are in the neutral position? The svc tech advised against compressed air. Any suggestions to get this system to prime? Thanks.

 

[J_J]

If you can easily get to the suction inlet of the pump, you might be able to feed fluid down a hose and fill the IN port of the pump.

Once the primes is secured, remove the hose and reconnect the suction tube.

 

[puckgrinder85]

Yea, the pump wont pump air, you'll have to get some fluid in there somehow if you can.

 

[xring100]

Have you tried blipping the throttle to max rpm a couple of times in succession this sometimes works when trying to prime water pumps in cars. Not sure if it works on hydraulics

Dave

 

[RJFEJF]

The inlet is on the bottom of the pump, and must pump up from the filter. Would a low psi boost of commpresed air to the fill port on the aux tank push the fluid up to the pump safely, a distance of about 1ft , till it catches prime? I have heard of this method used by others, however I do not want to damage any parts. I tryed raising rpm momentarly while operating 3pt. That did not work.

 

[puckgrinder85]

We've had this issue on our sportbikes but they are not a suction filter, its an engine pressure fed filter like any engine would have, we would have to start the bike and spin off the filter slightly to get the air purged before we could get oil pressure, really strange and only happened on that style bike. Have you tried maybe filling the filter before spinning it on?

 

[J_J]

5 to 15 lbs of air might help.

You need to get some fluid on the gears to have suction. The gears are probably spinning in air.

 

[SSdoxie]

A little bit of air pressure in the tank won't hurt and IMO is best way to prime it. Use a blow nozzle on the air hose wrapped with a rag to hold some air pressure in the tank while cranking the engine. Any excess pressure that could cause a seal to fail will escape around the rag. Could also hoo a sho vac hose to the discharge,blowing side of the shop vac and use that.

 

[RJFEJF]

I think I will try the air with 5 to 15 psi. JJ should I add the air with all controls in neutral at first ( open center system ), then work the control on the 3pt first, then Fel and then steering or is the order umimportant? thanks for your input.

 

[puckgrinder85]

Shouldnt have to open anything if you're going to try it, if its open center fluid flows no matter what. Remeber to go easy, you dont want to pressurize the **** out of the case. You're just trying to get oil up to the pump is all.