943 transmission problem after filter change

I have a 4Z 943 that is new to me. We ran it about 5 hours and evrything was functioning fine. It appeared it had not been serviced in a while so i had some of my help service all of the filters and fluids. Upon restarting we have what seems to be a major transmission issue. When the travel lever is in neutral the machine runs fine but just as soon as you attempt to shift to forward the engine stalls abruptly almost like the transmission is locked down but when we shift to reverse it does not react at all.... no travel, no stallining or anything. I quizzed my guys about everything they did while they were servicing the transmission filter. Here is the rundown below...
..As they were raising the cab something happened and they accidently broke the front cast iron lever on the transmission that connects the linkage to one of the steering pedals. I couldn't get to upset because they were having to use a forklift and straps to raise the cab since the hand jack wouldn't work. I brazed it back together and reinstalled the control lever. The lever appears to be back to it's original shape but if it is not I can see where this would possibly put that pedal linkage out of adjustment.
My guys said that aside from that mistake everything else was straightforward with the filter change and lowering the cab back down. I looked at the travel lever linkage and all 3 pedal linkages and they all appear to be connected correctly. I really dont see anyway to reconnect them incorrectly. I am going to raise the cab again in the morning but I'm just hoping one of you guys can shed some light on what we've done wrong. I saw a link Nige posted about manuals and I am about to order the OM download from Cat's site in hopes that it has some descent pics of the linkage positions and adjustments so we have something to start with in the morning. In the mean time any help is greatly appreciated. Thanks again guys!

Does your help know anything about working on machines? Did they remove old seals and put new seals in correctly ?

Thanks for the reply BLS Repair. Yes they are very experienced in equipment repair and maintenance. We manufacture asphalt paving equipment as well as refurbish and repair a lot of what is mostly asphalt related equipment... pavers, rollers and graders.
However; this is my personal 943.

Does the engine stall in FWD at all engine RPMs?
When the transmission filter was changed, was the filter housing drained first? Not doing this allows oil from the dirty side get into the clean side.

Yes, it stalls at all rpm's idle to detent. Yes they drained the housing oil before pulling the old filter. I failed to mention in the previous post that we also changed the fluid along with the filter. What is strange to me is that the condition started pretty much as soon as we restarted the machine after the service. It literally stalled in less than 10 seconds after restart just as soon as I start out of neutral to forward. Because of this I would think it is a linkage issue but I just don't see where anything is out of place. I should also say that I have owned a 943 in the past and we serviced the trans filter in it multiple times without issue. Not sure what went wrong this time. Either my abilities are diminishing or my luck is running out! I just downloaded the OM and about to try to find a few photos for linkage reference for in the morning.Thanks for the reply Cmark.

One of these?

Yes, thanks Heymccall. The download from Cat did not work out. Apparently they sub that service to a third party and instead of a download we got a notice that our download was "on hold". Really! If I wanted to wait I would have bought a book or cd. Hopefully we can spot something obvious in the morning and in the meantime I'm going to round up more manuals via ebay for it. If any other thoughts come to mind please share them. Thanks!

So the cab was lifted without disconnecting the steering pedal linkages, correct?

There's nothing in the external linkages that can cause your symptoms. I sounds like something's got damaged internally. You will have to remove the lid and take a look inside. It should be fairly obvious what the problem is.

Cmark. Yes. I am pretty sure that is how they broke the lever and I am thinking that before the lever on the outside broke something on the inside of the case, opposite end of the shaft, jammed, slipped out of adjustment, bent or broke. I just don't see anything else they did causing these symptoms. I am actually hoping this is the case since it appears that the internal linkage parts are readily accessible under the lid based on the drawings I've seen. It has been several years back but I have been under the cover of one of these transmissions on my last 943 to replace the common seal failure there so we can handle getting in there with out much trouble. I just hope that if that is the issue, it will be something we can either repair or still get replacement parts for. I will let you guys know what we find. If anything else comes to mind please let me know. Thanks!

That's called an HPCU. Some pics on page 3 and beyond, here.
https://www.heavyequipmentforums.com/threads/cat-hydrostatic-transmission-overhaul.41449/

Thank you sharing that post heymccall. I enjoyed reading the thread and I am very impressed with Cmarks level of expertise!

Ok fellows, I think we found the problem. A clevis pin on one of the internal control arms also broke off when they snapped the external control lever. Looks like the pins are pressed into the arm so I think my best bet is to try to find a salvage machine and get another complete control arm. See pics. I will post results when I locate a new control arm and get it installed.

The complete lever assembly is available for under $100, and there appears to be plenty for sale used.

Or you can just get the pin for under $30.

Perfect! Thanks! I would prefer just getting the pin. I will be calling our Cat dealer to see what our fastest options are as soon as they open in the morning.

I assume that it's #20. My login shows it available in York, PA distribution center.

Thanks heymccall! That is exactly what I needed to know!

Great news guys! The old girl is running again! The replacement pin ($23.62)arrived yesterday and we got it installed today. Unfortunately we still have a small issue. It seemed that at least one of the pumps always whined a little in neutral like it was trying to pull but the machine would sit still. Now after our mistake with the linkage and subsequent repairs, the right track is noticeably pulling forwards when the machine is in neutral. I am wondering if anyone has the instruction information for readjusting the linkage assemblies. I assume the issue is under the transmission cover because both external transmission steering pedal levers are resting against their stops when pedals are up. Any help is greatly appreciated.

I am glad you reported the repair. Also happy for you that it worked. I have a 943 and I'm interested in how others are using and maintaining them , they are great little machines. Easy on fuel as well. I recently did an inframe on mine that cost me about 4000$. That included a new cylinder head as well. It starts so much better now in cold weather. I'll never understand why they went away from the 43 to the 939 either. I guess it was the bean counters.

The adjustment is on the screw in the part you broke in your earlier picture. You're meant to set it up with pressure gauges but the quick and dirty method is turn it one way until the pump starts to whine, turn it the other way until it whines again then split the difference. Should be good enough unless something else got tweaked.

Cmark said:

The adjustment is on the screw in the part you broke in your earlier picture. You're meant to set it up with pressure gauges but the quick and dirty method is turn it one way until the pump starts to whine, turn it the other way until it whines again then split the difference. Should be good enough unless something else got tweaked.

Click to expand...

Thanks Cmark! I'm afraid something else may be tweaked. We have tried the quick and dirty adjustment but could not ever got the pump (pumps) to calm down when adjusting. One thing that concerned me during the attempted adjustment on the control with the broken pin is that it sounded like the pump was cycling in and out of stroke instead of a gradual increase or decrease as we made adjustments. That has me worried that something else in the linkage is floating from excessive play (possibly other broken parts or wear). [I did fail to mention that the loader already had some pump whine when I bought it. I figured it was either out of adjustment or needed a filter change and looking back I'm pretty sure it was a pump trying to come on stroke against the parking brake while in neutral.] We have raised the cab again and we are about to remove the cover again and thoroughly inspect the linkage once more. Can the adjustments be made with the cover off? Also, I assume that the control we broke and the one like it are for pump centering. If that is correct, can you explain what the other 2 are for and do I adjust them for any reason or just leave them alone? We do have the brakes capped and plugged by the way. I did remember that from my last 943 with leaking seals. Thanks guys!