Section for komatsu d20,21 and similar grey market dozers

[Iron@Dirt]

dont know about d21 but our d39 heated up right away. found the torque convertor housing full of oil. the ring gear really heats things up. torque convertor seals were leaking trans oil into housing.

 

[tool_king]

I'm running straight water right now, still flushing it out some. The belt is tight, It was a little loose before but its tight now with no improvement. Fan blows outward. Radiator is clean on the outside. Seems clean enough on the inside, when I drain it, the cores drain too, no visible crud. With the cap off when its hot, the pump seems to be moving a lot of water. I don't know what normal is but its sloshing around a lot.

Temp wise, my gauge is faded so I don't know exactly, but its past the green into the white. Sometimes at the very edge of the green into the hot zone. It stays up there. I've not had it boil over yet but its hot. Higher RPMs drop the temp down a little but once its under a load it gets hot again. Not to the point of pegging the gauge but I don't feel comfortable running it.

I need to get an infrared thermometer and see what everything is actually at. I hate to spend the time and money on a water pump without knowing if thats actually the problem or not.

How is the hydraulic cooler is it clean ? Because that will make temp go up .Whats your email ?I will email the service manual so you have it .

 

[fireman9731]

The hydraulic cooler looks good. This machine really is in good shape for its age. Doesn’t look abused at all. The hydraulic cooler does seem to warm up pretty quick just sitting there. Is that normal? Fluid is right at top of full mark. I think I’m going to check the trans screen next to see if that helps the steering issue. I crossed a creek and on the uphill the left steering worked perfect for once. On flat ground it was back to not unlocking the clutch. I know I need to adjust the brakes too. The overheating still has me worried though.

 

[fireman9731]

This is the torque converter right? Should it be empty? By looking at it, I would guess there is some oil in there. There’s seepage around the lower bolt holes. No way for trans oil to get in there but I’m sure engine oil could end up in it. Would that contribute to overheating?

 

[epirbalex]

https://en.av-gk.ru/catalog/komatsu/d21p-5c/060020/
this could be what you are looking at , two plugs would suggest there is fluid in there #'s 8 and 9 are the plugs . You need a service manual .

 

[77Ford]

I thought my JD450C was running hot after I took my IR heat probe home from work (on advice from others) I determined my gauge is reading between 15 and 20 degrees warmer than actual.

 

[fireman9731]

Just got my service manual emailed from Tool King. You are correct, they call it a damper case and it should contain 1.5 liters of oil. I'll try to pickup a temp gun and go from there.

 

[epirbalex]

Just got my service manual emailed from Tool King. You are correct, they call it a damper case and it should contain 1.5 liters of oil. I'll try to pickup a temp gun and go from there.

Cleaning out the rubbish from the bottom will help , won't heat the dozer up but won't let it cool either . If you have the damper out I wouldn't mind seeing some photos of it close enough to see how it works .

 

[fireman9731]

No luck on the over heating issue. It will stay at the top of the green just sitting but as soon as its under load its hot. If it let it sit and run at about 1/3 to 1/2 throttle it will slowly cool down. I guess a water pump is the next thing to change. Its circulating coolant but I guess not enough. The fan has a slight wobble/tick to it also once its heated up. Anyone have any insight before I dive into it? Whats the chances the impeller is corroded and I'm not looking at a head gasket issue?

 

[Don Shilling]

I would be more inclined to suspect a dirty radiator, either external and/or internal.

 

[fireman9731]

I would be more inclined to suspect a dirty radiator, either external and/or internal.

Its clean as a pin on the outside. The inside looks pretty good to me. There is a little rust on the filler neck but everything else is clean and if I drain it, the cores empty as fast as the rest of it. The coolant that was in it was pretty crudy. It took several flushes to get clear water out of it.

 

[Don Shilling]

Before you pull the water pump maybe remove and test the thermostat. It may not be opening up properly.

 

[luckybull7]

Guys is there a complete Seal kit available to RE-SEAL the hydraulic control valve?

 

[Don Shilling]

When I rebuilt mine I didn't see a kit offered in the parts list. I had to purchase all the individual pieces.

 

[Mechaman]

Howdy everybody, new member here.
I'm in the market for a D20 or D21 in loader config. I plan on setting it up with a skid steer coupler so I can quickly swap between pallet forks and a bucket. This thread has been an amazing resource of knowledge about these machines! I have a few questions I couldn't find the answers to:

1) are there any particular concerns or known issues with the loader models to be aware of when I do my pre-purchase inspections?
2) I want to install rubber tracks on my machine. Does this require any other part changes other than just the tracks? In other words, I assume I could re-use my existing rollers and sprockets if they are in good condition?
3) I have seen pictures of these machines with winches. Has anyone had any luck sourcing a factory winch? I have plenty of fab experience so I could mount a 3rd party hydraulic winch and plumb in a control valve for it but I'd like to consider the factory option too.

 

[fireman9731]

Well the saga continues... Got the new water pump put on, pulled the radiator and gave it a thorough washout, got everything put back together, and it still runs a little hot but it never gets to boiling over. Every once in a while the temp gauge will spike then cool back down (which might be a symptom of my next problem)...

While dozing I noticed a spark down by my foot where a wire runs down between the floor board. That quickly turned into a few puffs of smoke from behind the dash. Gauges went dead. I parked it and pulled the dash. A few wires burnt in two from the shorted wire by my feet. I cant tell exactly which wires went to what to fix them.
Does anyone happen to have a wiring diagram? for a D21P-5. The repair manual and parts book I have were useless.
Thanks!

 

[Mechaman]

Well the saga continues... Got the new water pump put on, pulled the radiator and gave it a thorough washout, got everything put back together, and it still runs a little hot but it never gets to boiling over. Every once in a while the temp gauge will spike then cool back down (which might be a symptom of my next problem)..........

I can't help with the wiring diagram, but whenever I've had a piece of older machinery with overheating concerns and there were no obvious leaks or failed parts (water pump, thermostat, radiator, rad cap) I've had good luck doing a couple flushes with radiator cleaner from the auto parts store. Read the bottle of the radiator flush product to find out how much to use for the machine's cooling system capacity and mix it on the strong side. It's amazing what kind of gunk this can remove. I drain out the coolant, fill up with just water and the radiator flush product, run it good and hot for a while, then let it sit overnight. Next day drain the system then repeat a second time with new water, rad flush, and a good hot run. Drain, rinse it out with clean water to remove any traces of the flush, then refill with new coolant with Red Line Water Wetter added. This has never failed to work for me.

The temp spikes you saw on the gauges could easily have been caused by the wiring short, or could also be the result of air bubbles working their way out of the system after you replaced the water pump.

 

[fireman9731]

I’ll try another flush for a longer time. Couldn’t hurt anything.

 

[fireman9731]

Luckily I was able to figure out the wiring today without a diagram and now I’m back in action. I also found a worn spot in wire going to the temp sending unit, I’d say that is the culprit for the random temp gauge pegging. I’m also working on another flush. I plan to run it most of the day tomorrow working on clearing a new fence line through some tough brush. Thanks for everyone’s input. I’d be lost without all the knowledge here.

 

[Krackerjack9]

On the overheating issue im sort of in the same situation, have tried it all, but the temp here in the summer close to 100 most of the time and the needle gets with in one or 2 needle widths from going into the red, I put in some additive that makes the transfer of heat more efficent and that does work i say it stays a good 2 needle widths cooler but if im using the dozer pretty stead /hard the temp still goes up close but never over. most of the time its due to debri in the fins and a quick power wash always helps . but temp now in the low 80s so not much issue with it getting to warm now