Case 621C ZF trans problem

[FastYZFR1]

Hi I have had an old 621 for a few years now and put about 500 hours on it. The transmission has been behaving very good with the exception of transmission overheating according to the gauge after a few hours of working it hard digging in dirt. I am near Chicago and use the loader to push a 16ft snow box. Today I went to use it and it moved a few hundred feet then slowed to a stop. The day before it was working great moving snow for 4 hours or more.

I put the 15w40 motor oil in the trans when I bought it, was getting ready to change it to HD30 the overnight temp was in the 1-3 degree range overnight. I started it and let it warm up about 15 min and went to move it and it moved a bit then stopped. Letting it sit and idle for an hour or so it moved another few hundred ft then stopped again. I changed the filter (oil looked fine) still didn't want to move. I let it run for another 4 hours now it would move but after just driving it 1/8 of a mile in 1-3rd gears different directions the gauge would indicate trans overheating but it didn't seem to get too sluggish Though I didn't run it with the trans overheated I didn't want to do any more damage to it, any ideas?

it's a 621C with 8200 hours on it, I tried to do the trans calibrate and it seems to only get through doing 1st then stops in 2nd gear, I was able to get it to go a lil further if I increased engine RPM but it still wouldn't complete the process. I am thinking either it lost the converter or blew a seal in a clutch pack or maybe even an issue with the charge pump.

Thanks for any help
James

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[Tenwheeler]

Look at my last post on JCB 436? I know it is a bit different but I thank they are both ZF's. Some other people on this forum really helped me out with this. Also had a 621 trans problem years ago. It had a broken spring in the valve body.
Maybe someone can get you some trouble shooting info to narrow it down.

 

[GaryHoff]

Sounds likely that your transmission pump is weak. I would recommend to flow test the transmission pump. Your Case dealer will have a flow adaptor that will screw onto the filter head. Other ZF dealers will likely have a similar tool.

You could also check your transmission pressure, it will likely be low.

Low pump flow would cause the transmission to overheat. It would also cause the calibration to fail, and cause low transmission pressure. Higher engine rpm would give more pump flow, and help the calibration continue.

 

[FastYZFR1]

I sorta am thinking it may have blown a seal in the pump, I am worried it may have blown a seal in a clutch pack but it dose seem to work in first through 3rd (haven't tried 4th but I am sure it's fine) just acts like it's got low pressure over all after it was well warmed up it did seem to go in gear nice and firm from forward to reverse and would turn the tires over easily in the snow pushing against something but I haven't done much more with it not wanting to cause any more damage. I have used the crap out of this lil loader once I got the issues it had when I first got it somewhat resolved
Not sure if draining the 15w40 and putting in HD 30 trans oil would help for checking pressures. I should have done this months ago like I was planing but I got lazy and it worked fine with the 15w40. I can't help but blame myself although with the previous overheating issues it may have had somewhat weak pressure to begin with the trans oil looks pretty clean so I don't think I did any major damage to clutch plates yet. Thanks for you help Gary

 

[FastYZFR1]

I have talked to a few people that have had these transmissions appart they said there is a tube in the case that feeds oil to the converter from the pump, sounds like mine might have cracked. Trans has to come out and be torn down completely to get the tube replaced

 

[William Schuda]

Does any one know what size make or style the trans pressure test connection are? I need to build me a test gauge to test mine. I am looking for a female quick connector that will fit the male test fittings.

 

[alrman]

Google - Parker PD fitting

 

[Rihpper]

We have a 621b, I’m not sure if the transmissions are the same or not. It had a intermittent issue of the trans not going in gear at all, wouldn’t even try. It ended up being a electric solenoid on the top of the trans. I think there are a couple there. You can change them pretty easy. Yours is a little different issue but maybe worth a look.