Author Topic: Clark 28000 in TJ Skidder Problems. (Read 2728 times)

Spartan · « **on:** June 04, 2016, 02:36:40 PM »

So I have been trying to hammer out the issues in my TJ 450a. Got a few of them solved. One that is tough to track down is the transmission issues. I thought that I had a bad trans pump, but now I am thinking that it may be a different issue.

I put a new filter in and changed the oil. (suction screen is clean) I can feel and hear the pump as if is is cavitating (power surges a little) and the machine has a higher stall and less power. Oil is aerated (Sometimes) especially when cold, Not so much when hot. I thought it may be the pump originally but then I had a couple days where everything was right in it and it performed flawlessly, never had that much power before. But then it went away and back to higher stall and sounds like cavitating at high rpm. Especially at high load.
Performs better when hot than cold.
Pressure on the dash reads good for all clutch pressures in all gears. Gauge is plumbed to top of pump.
Oil was discolored from before, but did not smell burned. but looked as though it might have been.

Does that sound like Trans Pump to anyone? Or, do I have a suction tube issue?
Don't want to throw a pump at it just to have a different problem. It is not the same all the time, fluctuates, in degree of severity.

If it is the suction tube, any way to tell without breaking the trans apart from the engine?
Is there a way to check it with the pump removed?

Thanks, Brian

treeslayer2003 · « **Reply #1 on:** June 04, 2016, 04:07:04 PM »

oldseabee?

Spartan · « **Reply #2 on:** June 04, 2016, 04:25:43 PM »

I was hoping he would chime in.

I remember I had asked some questions when I first got the machine, but there are further developments, so I thought I would bring it up again.

oldseabee · « **Reply #3 on:** June 04, 2016, 11:47:58 PM »

Could be sucking air where pump mounts to trans case, pull the pump and smear some gasket maker on the mating faces, there is no way that I can think of to check the supply tube internally without seperating the case, just had a thought, if you can remove the suction screen and plug the hole then take the pump off and force a short hose in the supply tube and hook it up to a hand vaccuum pump and see if you can suck air, that would tell you that there was a leak but not where.

Spartan · « **Reply #4 on:** June 05, 2016, 09:10:28 AM »

Thanks

There's also O rings in between the pump and the trans too, right?

oldseabee · « **Reply #5 on:** June 06, 2016, 06:14:22 AM »

I guessed that you would have checked them first.

Spartan · « **Reply #6 on:** June 06, 2016, 11:54:46 PM »

So I pulled the pump and regulator block off today. All the mating surfaces were siliconed very heavily and one mounting bolt was not that tight. I do not think it is the original pump.
My guess by the way things look is that they replaced the pump but nothing else and just slapped it back together. (about normal for the guys who had it before me)
It has the same pump number I see for all the aftermarket ones online. 235045 is the number stamped on it. bearings and everything feel tight in it, no play at all.
Anyways, the o-rings are pretty hard and collapsed, got new ones to install. One of them was even out of round in the slot (bottom port of regulator block) and that was the one near the loose bolt. going to clean all the surfaces, don't have a new gasket so I will reuse the old one, and put some small amounts of silicone on it.

One thing I noticed is that the pump drive shaft oil seal is not in good shape.
Is it just a oil separator from the converter housing oil?
It's the one in the regulator block that goes around the pump shaft. Doesn't look like a high pressure area.

I'll have it together tomorrow and we'll see if it makes a difference.
I did stick my finger in the suction tube and tried to wiggle it, seemed like there was no play and solid. Probably can't tell by that anyway.

What does the bottom port in the regulator block go to? I see where the suction tube is, and the valve oil supply tube, they are the top tubes. can't find a description that tells where the bottom port goes to (o-ringed port, converter side of regulator block)

oldseabee · « **Reply #7 on:** June 07, 2016, 06:48:57 AM »

Oil flow as follows: first oil from charge pump goes to trans control valve and one of the speed clutches, (one of them is always engaged,could be any speed). Once clutch pressure is achieved the regulator valve shifts to send charge pump flow to convertor, that way you are always have clutch pressure before the convertor gets any oil to transfer to send any power from engine to the transmission except for that one speed clutch, you have to have a speed clutch and a directional clutch engaged to go any where. All that said, there is a convertor pressure relief valve that will dump excess convertor oil into convertor case to drain back to transmission, this in case there is a blockage in the convertor or down stream to the cooler, filter, or transmission lube circuit.

Spartan · « **Reply #8 on:** June 07, 2016, 07:03:53 AM »

Thanks

Spartan · « **Reply #9 on:** June 07, 2016, 08:25:45 PM »

Didn't fix it. But, I think I know the problem. Part will be here in a day or two and I will follow up.

Spartan · « **Reply #10 on:** June 09, 2016, 10:13:49 PM »

If anyone cares, It was the charge pump driveshaft oil seal in the regulator block. It was allowing air by.
Converter starts to hook up about 500 rpm lower now.

kiko · « **Reply #11 on:** June 10, 2016, 12:24:17 AM »

I for one always like to hear the solution.

oldseabee · « **Reply #12 on:** June 10, 2016, 10:09:01 AM »

Great, always like to hear solutions to file away for future reference.

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