Cat 973 track loader won't travel or move but Engineeing and everything else works

We started and moved this machine and upon reversing, machine stopped moving. We noticed oil in the back and a busted hose. Replaced hose and filled the associated transmission oil. Which was totally empty. Machine still won't move. We couldn't figure out where to bleed the pump from but we tried to bleed through the hydraulic filter still no movement. I don't have a manual here where this machine is on project in Africa. Somebody help me. I'm not a Cat mechanic and know little about this thing.

What series and serial number.
Later Bob

Cat 973 Track loader movement issues

Bob/Ont said:

What series and serial number.
Later Bob

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Bob

The Serial number is 86G03028
This machine is the first 973 trak loader. No letters after 973. Itis just Cat 973 plain.

Okay that machine I know something about. Fill the oil to the sight glass, start machine and if you have no leaks try moving it at half throttle. If it moved you might have a clogged filter. Come back with what you find.
Later Bob

Bob

We have filled NE gauged oil to the sight glass. The only thing is that we noticed oil leaking from where the main pump connects to the movement pump. I m assuming this leak may have been there before this problem started yesterday. Thank you so much. Could this leak cause the machine not to move. Mind you ths machine was moving before the hose busted.

with cold oil and or a partially plugged trans filter it will go into bypass at full throttle and the machine will stop.

How much and what type of oil did you add?

We added 30 wt. hydraulic oil up to full on sight glass on one of the fill caps whie the on next to it was overfilled on the dip stick. We removed some oil tidy from that. Now both levels are within normal. What bothers me is that machine won't even move an inch. I'm new to this sight and unaware of any restrictions. Is there anyway I can peak with you.

10w is recommended but 30w wont stop the machine moving.

How cold is it? below freezing?

Make sure the center pedal is not stuck down.

Does the machine growl or do anything when you try to move it. Did you try at 1/2 throttle?

What hose blew?

Serial number is 86G03028

It is really hot here. The machine is in Africa now. We couldn't find 10 wt oil yesterday so we used 30wt. We also have checked and confirm that the middle break is not stuck. All the linkage joints are moving well for all the pedals and levers. Thank you. The hose that blew is under the rear of the machine which a mechanic here traced to a transmission valve. That's what we traced to realize that the oil tank was totally empty before we added oil. Please keep thinking since you are making all the points my USA mechanic is suggesting. thank you. We have tried both middle and fll throttle still no movement.

Oh, i hope the operator shut it off before it totally ran out of oil. The HPCU (trans) doesn't like to be ran dry.

Was the cab lifted to replace the hose? Maybe forgot to reconnect a linkage?

What noise is it making when you try to move it?

I have seen hoses made wrong and the crimps were crimped too much blocking any flow.

The gauges were really empty and of course with hose bust, the machine stopped totally empty although there was oil in the main hydraulic tank. The trans was empty. The cab was not jacked up. We replaced the hose from under the machine. It is not making any sounds if we want to travel. The operator told me he heard a little undescribed sound when he stepped on the stearing pedal.

My guess is they ran it long enough to ruin the HPCU. Tell them to check for charge pump pressure by the filter housing and come back with what they get.
Later Bob

If you get any pressure I want you to check pressures at the 3 fittings on the front center of the HPCU, not on the top, on the front half way down in the center. Need 600 to 800 psi gauges.
Later Bob

The machine has not worked for 18 months since exported from USA. It only sit and started once every two weeks to keep battery charged and oil flow for 10 minutes. It is moved forward 5 feet and back. Hasn't travelled more than 100 feet in 10 18 months. Hasn't worked for 1 minute.

I guess you mean the allyn key screw on the filter housing. We got pressure but but not gauged sincewe have limited tools. We also bled two screw nuts on the side of a valve on the trans again pressure but not sure what the psi is. Thanks.

Exodus said:

I guess you mean the allyn key screw on the filter housing. We got pressure but but not gauged sincewe have limited tools. We also bled two screw nuts on the side of a valve on the trans again pressure but not sure what the psi is. Thanks.

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Well that tells me the charge pump is working and with an oil change to 10W you should get some action. However, the machines condition is suspect to me since you have recently acquired it and never had a chance to work it for a day. The fittings I ask you to check pressure at should all have pressure taps(nipples) to snap a gauge line quick connector onto. This might seem like a big request but you will need to get about a dozen of these connectors some test hoses, two 8,000 psi, five 6 or 800 psi and two vacume to 30 psi gauges. One of these connectors for the RH drive pressure needs a very close 90 deg elbow to fit between the fuel tank and the end of the nipple. Lee on here can likely post a pressure test sheet for you to follow while testing. The pressure test needs to be done with the oil at 175 Deg with a tach on the engine and a flow meter on the cooler line . I doubt your people out there have an inline flow meter so the amount the charge pressure drops to should give us an good indication.
Later Bob

Forgive me since it's been some time since I've been around an A model 973 but some things sound weird here. When you're filling the hyd tank are you filling the hyd oil tank for the loader or for the HPCU?

I have seen the hydrostat oil tank run dry a few times, it's bad but you've gotta let her crank for awhile before it craps the bed. You'd also hear some awful noises out of the HPCU before it happens. Pull the HPCU filter and check it out because it will have all sorts of shavings in it if you've done any damage to it.

To bleed the system fill the HPCU tank to the top of the sight glass, start the loader and loosen the cap on the tank you'll hear air rushing out and the levels will stabilize. Most 973A's won't move at half throttle once they have a few thousand hours on them, try at 3/4 throttle and slowly move the lever and see what happens. Don't bother steering since it will just bypass. Bob/Ont is correct you should have 10wt oil in there, we use a 10wt Spirax oil in our 973's and we've had good results.

The little dipstick, that's the pump drive. Leave it alone it doesn't hold much oil and you'll be having all sorts of problems if you start messing around in there. That's a check only kind of thing and it will rarely be down unless you're having bigger problems with the machine.

When you changed hoses to the drive motor...did you remove any of the little service plates? The 30wt oil in the HPCU probably isn't a big issue in Africa, it's warm and you don't really need the thin oil for cold weather. We run 10 because in the winter/fall you tend to blow hoses right off the pumps as soon as you start the machine.

If you changed a hose to one of the drive motors you will need to bleed air from the motor circuit.

To my dear helpful friends. I wish you all a happy thanksgiving weekend. As of today the machie have not moved an inch yet. I left Africa to celebrate thanksgiving. I will update once I hear from a new mechanic I got before leaving. Thanks again for all your help. I believe with your help, we'll getting going. Ken