D4D powershift

[BradleySherrell]

I’m having issues with my D4d dozer, not sure on the year model I’m thinking late 60s early 70s. Serial is 83j839, 1st gear fwd, and rev always work good. Second gear forward and reverse it will pull its self when cold but will not push dirt. And barely loads the engine. When transmission warms up it won’t even pull itself in second gear fwd or reverse and doesn’t load the engine at all. 3rd gear forward and reverse works cold and hot will pull it’s self but doesn’t have much power either way. Won’t spin tracks to steer in 2nd or 3rd. I’m new to this dozer as my grandpa had it and it sat for 10 plus years. Only gears it will spin tracks in is first gear. And after you work it 4-5 hours the trans temp gets on the line between red and green. Appreciate any help or pointers I can get

 

[Nige]

How mechanically-minded are you..? Diagnosing the problem might need a bit of wrench-twirling.

Does the tractor put out a good puff of black smoke from the chimney when you change direction from fwd to rev and vice versa..?

To be pushing a blade full of dirt the tractor really should be in first gear. Fine finishing work with minimum material on the blade could probably be done in 2nd.

 

[BradleySherrell]

I’m aware of How transmissions and hydraulic valves etc work just not this exact transmission, and turn wrenches for a living and run equipment on the side. But it blows a good amount of black smoke when you go from first fwd to first rev, like I think it’s supposed to but the other two gears do not load the engine. Shouldn’t it atleast pull its self in second gear at operating temp?

 

[Nige]

Sorry about the questions but it's always good to have an idea how mechanically-capable a poster is before starting to offer suggestions that may or may not be fully understood. Here are a couple to start with: -

1. Lift up the floor plate and with the machine up to full operating temperature watch the drive shaft between the converter and the transmission. It will spin in neutral but should stop dead as soon as you engage any gear. Try shifting N->1F->2F->3F, then the same back to neutral. Repeat in reverse and back to neutral. The shaft might turn a few degrees when you shift from one gear to another but generally speaking once you shift out of neutral to any gear the shaft shouldn't turn. A slipping clutch and the shaft will most likely creep in that gear both forward and reverse.

2. Take a look at the illustration below. This is looking at the transmission from the right side of the machine. Item 15 in the illustration is a screen. To get at it will need the transmission oil to be drained, but if you have a clutch starting to let go the first indication should be in that screen. If you find any material in it take a photo with something like a ruler alongside to give an idea of scale and post it here.

 

[BradleySherrell]

Ok Nige, thanks I will drop the belly pan drain the oil, and pull the screen. Just to be clear if you’re setting on the machine, it’s the right side, front, of the transmission on the bottom correct? And the drive shaft between the TC and transmission can’t be seen from the top of the transmission with the floor plate removed I don’t think, I’ve had the floor plate off and all I can remember seeing is the flex drive coupling between the TC and the engine. I work second shift mechanic, I’ll be at the dozer tomorrow to take another look when I drop the pan and take the screen. I’ll let you know what I find

 

[Nige]

I think you'll find the screen is on the left side lower front corner of the transmission as you sit on the machine. You may be able to access it from above with the floor plate up. It's behind a circular cover with 6 bolts. Here's a view of the complete transmission from the RH Side of the tractor.


This machine doesn't have a drive shaft between the TC and the transmission like the larger machines I'm used to. Unless there is some way of seeing the output side of the TC that idea's probably a non-starter.

 

[Bluox]

If you pull that screen you will drain all your oil. I would pull filter under your right foot first.
Bob

 

[Nige]

When you drain the oil have a good look at it. Is it clear or dark, does it appear to be dirty, and more importantly, does it smell burnt..? Do you have any idea what type and grade of oil is in it right now..?

 

[BradleySherrell]

Bob, I changed the oil and the filter at your foot about a month ago and helped the machine quite a bit until it got back in its same old ways, I still have that filter I may cut it open tomorow to see if there’s anything in there.

Nige, I also changed the transmission oil when I changed the filter I mentioned above, the fluid didn’t really have a burnt smell that I could recall but it was in fact dark rather then clear. And It has sae 30 oil in it right now, it’s what the service manual said it took.

 

[Nige]

Ah, you never mentioned that you the oil had been changed recently. Specifically what type of SAE 30 oil does the service manual recommend and what did you put in it..?
If you still have the old filter cutting it open and taking a peek at the bottom of the pleats might shed some light on the subject.

 

[Dave Neubert]

pull the magnetic strainer and see if you have any aluminium in it sounds like a bad torque convertor

 

[epirbalex]

Bob, I changed the oil and the filter at your foot about a month ago and helped the machine quite a bit until it got back in its same old ways, I still have that filter I may cut it open tomorow to see if there’s anything in there.

Nige, I also changed the transmission oil when I changed the filter I mentioned above, the fluid didn’t really have a burnt smell that I could recall but it was in fact dark rather then clear. And It has sae 30 oil in it right now, it’s what the service manual said it took.

Has the problem shown up since the oil change ? It does sound more like a torque converter on the way out rather than the transmission . Too many in the box out at once while only one choice with the inverter covers the lot

 

[BradleySherrell]

Hello guys I have been on vacation since Thursday and haven’t got to dig any deeper into the dozer but will dig deeper tomorrow to let you know what’s in the old filter and in the suction screen.

Nige, the oil it specified was sae-30 cd/to-2 oil, and I just used regular sae 30 oil. Maybe that’s an issue as well?

Epirbalex, no the problem was existent before the oil change, the problem did get better for a few days and started doing the same thing again.

I did do some pressure checks this evening under the top cover of the transmission, my manual said the direction clutch should be 50 +/- 8 lbs In all gears forward and reverse, and the speed clutch should read 275psi in all gears and 75 psi in neutral. The speed clutch specs were right on, but the directional clutches were off really bad. Each gear was over 200lb. 1 fwd - 210psi 2 fwd - 250psi 3 fwd - 275psi. 1 rev - 175psi 2 rev- 225psi 3 rev - 250psi. I don’t think this is right. Maybe a relief valve is stuck closed somewhere? But I didn’t check the machine at operating temp, but even at operating temp I don’t think the psi should vary that much. Also on the overheating I’m gonna pull the cooler off tomorrow while I’m into it to check for blockage.

 

[Mark250]

Hi ,I think you have misunderstood the test spec's. the direction clutch's are 50 psi LESS than the speed clutch's in all forward and reverse ranges
did you do these checks at high idle and at operating temperature ?
the low side spec is 275 psi and high idle is 305 psi
yours seem a bit low
Can you also check the lube pressures and the torque convertor outlet pressure as well?
Mark

 

[Nige]

Echo what Mark said above regarding direction clutch pressure is supposed to be 50psi less than the measured speed clutch pressure in any particular gear. Also the importance of having the whole machine (not just the engine coolant) at normal operating temperature before making these checks. They are not supposed to be done cool/cold.

Regarding the oil, a regular SAE30 is not the oil for this transmission. The TO-2 specification oil called out in the book has now been replaced by TO-4, so you should be looking for an oil that meets TO-4 spec. These oils have friction modifiers in them designed to work with mulitplate clutches and brakes where straight oils don't. Although I would love to say it so I don't think the oil is the root cause of your problem. Something is wrong somewhere, just need to find out what.

 

[Bluox]

Have you checked the shift linkage for wore out parts and checked the adjustment specs ?
Bob

 

[Dave Neubert]

Check the converter inlet pressure I don't know the specs should be around 50 psi. I would think

 

[Nige]

TC outlet pressure spec.......
Test with ALL machine systems at normal operating temperature, transmission lever in 3rd Speed Forward, Brakes applied, and torque converter in a stalled condtion.
Governor Control at minimum position - 4psi minimum
Governor Control at maximum position - 40+/-10psi.

 

[BradleySherrell]

Mark 250, yes I will check the lube pressures and TC inlet pressures as well. But I did mis understand the manual about the 50 psi less then speed clutch.

Nige, I will run the machine until it gets to operating temperature next go around. And regarding the oil, I will try to find some to-4 oil at the local parts house and put that in next time with a new pressure filter.

Bluox, I have checked the linkages, the linkages are good and make firm shifts at the shift lever and at the transmission.

Dave Neubert, I will check the inlet pressures as well, the book says it should be 110 psi +/- 10 psi.

 

[Nige]

Check the converter inlet pressure I don't know the specs should be around 50 psi. I would think

Spec for converter Inlet pressure P3 (bench test spec for correct operation - no adjustment) 110+/-10psi.