Hey Fellas,

 Basically very late last year i started my Dozer ready for a delightful day of earthmoving and it wouldn't go into gear. Forced out on the low pressure spring.

Got a new pump from Tilly's (ITR brand), installed it and went back to dozing away.

I've probably put 20 hours on the machine this year and last week (after i picked up my ACMOC magazine from the post office that reminds me my membership is due) went to start it and it's springing out of gear again.

When you first start it it's fine, after a few minutes it looses pressure. When you rev it up you can hear the pump kick in and it makes the correct pressures at the test ports on top of the trans (350psi and 250psi or 300 and 250 from memory but we checked it against the book and it was good), drop the revs with the decellerator and the pressure drops away. When you remove the pressure guage line the oil is really air-rated.

When the machine is cold The Converter oil pressure guage shows High in the red, once it warms up it sits in the upper green area. When it's having this issue while cold the converter pressure guage reads in the middle of the green, when you rev it and get trans pressure it goes up in the high area, once you lose the pressure it drops back to sitting in the middle of the green or low green) Not sure if this is related but just something i noticed.

Removed the pump and it's making all the right squelching noises, no movement, drive gear is on ect.

Pickup Hose between the trans and the pump is only 5 years old, plenty flexible and Cat hose clamps that are nice and tight. Replaced the O-ring on the trans side as it had a minor damage to it but no difference. O-ring on the pump side of the pipe is good.

Filter after the pump is clean (one very minor piece of what looked like silicone), there isn't a pre-screen installed on that side, it was a bit of an inbetween S/N where they started going to the magnetic screens up by the engine, and they are on the clutch/steering side.

Put an extra 10l of oil in and no difference, no major leaks to loose that much oil quickly anyway. Oil level comes up the stick in the low pressure state and well above the add line when it's got pressure.

Anything else i can check? O-rings on the tubes that run inside the trans were replaced when we rebuilt it 5 years ago. I don't want to go in there again. Is there something i can spray or put on the pickup line to see if it's sucking air through a crack or somthing?

www.acmoc.org/bb/discussion-d72/32122-ca...g-in-gear-at-low-rpm

This bloke had a very simular problem but i was expecting more then 20 hours of out of a pump that cost me over $1000...

66A01872

 

Thanks

Did you taper back the splined drive shaft of the new pump so that it didn't bottom out on the worn drive spline. Maybe if it bottomed out the gear has been driven into the pump face and badly scored it. This is a very common problem and mistake when fitting a new pump to an old machine.

Wombat

I like Wombats theory, not an uncommon occurrence. Other possibility is a broken load piston spring.

I got a mechanic to install the pump as I was out of town.

Picture of the old pump. The gear goes on the taper where the keyway is and held on with a nut and a split pin, and the transmission hole where it bolts in. 

Is there a procedure for this wombat? I guess I can take the pump off and check the distance between the face and the gear and compare it to the old pump. I'll check if there are measurements are in the book

If the pump was scored inside wouldn't the filter after it be full of metal?

 

The splined pump shaft concern does not apply here as the transmission pump is gear driven.

If you had the bottom of the suction hose off and didn't lose all the oil in the transmission the suction screen in the transmission is plugged.
if the screen is plugged the pump seal may past air.
The hose needs 4 clamps on it.
If it's not a secret a serial number would help .
There are some real masters of the obvious on here.
Bob

No screen on this side. The D9G has 2 pumps, one for steering and brakes and one for direction and lube. The screen is on the Steering circuit.

The suction hose elbow bolts onto the front of the trans and there is 2 tubes that run all the way to the back and the pickup is in the bevel case 

   

SN 66A01872

I'll see if i've got any more of the right hose clamps in the shed. Thanks

What you describe seems pretty normal for those early units except for the aerated oil. I would recommend using real gauges to do you testing rather than relay on iffy gauges. Yes there is no pre-screen protection for those early transmission pumps something that was added in the next series.
The only way I know to check a suspect hose is to remove and blank flange and pull or attempt to pull a vacuum.

OM is there an update to retro fit a screen for the pump? just a thought, (maybe it was in progress and only for the later model)

I don't see an update called out in the parts books but both suction tubes through the transmission are the same part number and either side used the same part number screen so I don't see any reason why you couldn't add the second screen.