KOMATSU D20A-5 ADVICE AND INFO.

[Thumbs Up Farm]

Yes once "My Komatsu" account was set up I was able to copy and paste all available illustrated parts list for the entire machine. It took a while but I got every section.

From what I understand the only places that fluid can leak into is either the outside of the machine (under the seat is a likely place) OR worse the steering clutch / break cases one on the left, one on the right. I do not see a way the clutch pump fluid could get into the final drive transmission.
The Steering clutch / break cases should be completely dry, the final drive transmission is in the center and divides the two halves. Under the final drive there are three drain plugs, the center is the final drive, the left and right are for the steering clutch / break cases. If you remove the left and right drain plugs for the steering clutch cases there should be no fluid in there. Maybe a bunch of rust and dust.

Thanks, again!

I am still trying to get "My Komatsu" set-up. They promised to at least let me know something today. They seem like really nice helpful folks but so far I am making no progress in getting set-up.

I will remove the drain plugs for the steering clutches first and see what comes out. I don't think there will be any fluid because neither track slips when I push against something immovable. They both spin at the same rate. I will also remove the brake band covers, adjust the brakes, and vacuum whatever dust and debris I can out of the clutch drains at the same time, prior to putting the brake band adjustment covers back on.

I suspect you are right about the clutch pump leaking under the seat. Based on your picture above, it looks like a pressure tube from the pump sealed by o-ring 26. Which, I assume, feeds the steering clutches valve. But, how does the oil return from the steering valve to the clutch pump? Is there perhaps a low pressure return hose? Any speculation on where the leak might be under the seat or how to repair it? The seat brackets and adjusting mechanism is virtually gone due to rust. So, I will probably try to remove the entire seat plate/platform with seat attached if that is possible. Maybe then I can locate the leak.

The rear trans is obviously over-filled. So, maybe I should drain and refill it or at least drain off the excess?

 

[GuglioLS]

But, how does the oil return from the steering valve to the clutch pump?

It is an open loop system, meaning there is no return except back the way it came. The "Main Clutch" pump inside the clutch bell housing has a built in pressure relief valve. When the steering levers are pulled back a valve opens allowing pressure against a large Cup piston that pushes a yolk releasing the steering clutch. When the Steering lever is returned to normal, the springs on the steering clutch push the fluid back through the piston.

The rear trans is obviously over-filled. So, maybe I should drain and refill it or at least drain off the excess?

Yes drain it to the correct level, collect the overfill into a clean container to check the fluid condition.

 

[Thumbs Up Farm]

It is an open loop system, meaning there is no return except back the way it came. The "Main Clutch" pump inside the clutch bell housing has a built in pressure relief valve. When the steering levers are pulled back a valve opens allowing pressure against a large Cup piston that pushes a yolk releasing the steering clutch. When the Steering lever is returned to normal, the springs on the steering clutch push the fluid back through the piston.

I am a bit confused. I was looking at my CD and I saw the attached diagram that shows a connection from the steering valve to the "transmission case". Is this a mistake in labeling/terms or is this some sort of bypass/dump from the steering control valve to the transmission case??

It is beginning to look like there could be an issue with the steering control valve leaking/bypassing fluid??

 

[Thumbs Up Farm]

Today I drained the excess oil from the rear transmission. I am not sure how much it is supposed to hold but I drained out about 1 1/2 gallons. The oil that came out was darkened but had no signs of water in it. There were some metal particles but none were any size, more like fine glitter. Is this a major cause for concern or is this to be expected for a dozer?

I also removed the drain plugs under both clutches while I was under the dozer. There was no oil to come out but there was a cup or so of water in each side.:shocked: Also, both drain plugs had a hole through them which was plugged with dirt and crud. I assume this was done by the previous owner to let out the water. So, I cleared both holes. There was a foreign object in the LH clutch housing. It felt like a flat piece, maybe a brake pad?? Not sure what it is. I plan to use a smart phone endoscope to try to get a look at it and the brake.

I refilled the transmission to the lower mark on the dipstick. As best I could tell, it had about 2 qts. excess which roughly equals the amount I had added to the main clutch reservoir. This may have just been a coincidence. I really don't know because the transmission was overfull from the beginning. However, I will keep a close watch on the fluid levels and see if the transmission fills up more as the main clutch goes down. If so, I think it safe to say there is cross leakage somewhere, probably through the steering control valve.

I also looked at the steering valve under the seat and there is definitely some leakage to the outside there. How much trouble/cost is involve in repair of the steering control valve?

 

[Thumbs Up Farm]

If anyone is still reading this thread I would like to know what brand/type oil you used in the main clutch. The book calls for SAE 10W-CD. I have been unable to find this oil or a "for-sure" equivalent. The Komatsu dealer service techs said I could use a Hydraulic/Trans type fluid from TSC. I am wondering what brand/type you or others are using in the main clutch. My concern is that some of the post I have read warn of the clutch pads breaking down if the wrong oil is used.

BTW so far I have run the machine 3-4 hrs. with no change in the oil levels from the main clutch to the transmission. Oddly enough the main clutch fluid level has not been dropping like it did the first few hours. Is it possible that the seals stopped leaking after being used a while?

I should have access to "My Komatsu" by Wed of this week. According to the service guys, it took longer because these are grey market machines.

I am in the process of gathering all the needed fluids, filters, and parts to change the fluids, filters, clean screens, and make clutch/brake adjustments. Working full time doesn't leave much time for my new toy.

Any feedback/info on brands and results is appreciated.

 

[John White]

You might ask Komatsu, but on some wet clutch types you don't want to use any 10wt detergent oil. It will soak into the discs or pads and become slick and will give you a lot of headaches. Usually the cheap hydraulic oil is non-detergent. I think they go by a ISO # like 32.

 

[Thumbs Up Farm]

You might ask Komatsu, but on some wet clutch types you don't want to use any 10wt detergent oil. It will soak into the discs or pads and become slick and will give you a lot of headaches. Usually the cheap hydraulic oil is non-detergent. I think they go by a ISO # like 32.

This is exactly what I decided to do. Komatsu had the correct oil for the clutch in stock so I just bought it from them. It is a straight 10w engine oil. But, the 10w engine oil at TSC was mineral oil based, which was not recommended. None of the oil standards called out on the containers were equivalent to the "CD" callout in the manual. The dealer oil cost more initially but, perhaps not, if this prevents damage. The piece of mind is worth the extra cost.

The dealer also got "My Komatsu" set up so I can see the parts break down images and part numbers. So far, I am liking this machine and have got a lot of work done with it.:thumbsup:

 

[ultrarunner]

A reliable small dozer is very handy to have around.

It was hard for me to part with mine even though I had reached the point where I could maintain the firetrails in a less than a day's seat time in a year.

I did start and run it through the motions about every 6 weeks... which helped a lot to keep everything tip top... put the front blade down and the rear rippers and I could run the forward and reverse not going anywhere.

 

[skyhook]

Don't know if this will help, but JCB sells a 10W trans oil.