Komatsu D155A-1 Dozer wont move

[epirbalex]

After taking almost everything apart in the transmission and steering, replacing a lot of o-rings, and waiting several months for back ordered parts (that didn't make a lot of difference), I am starting to think that the original advice of replacing the transmission pump ($3500) is correct. This is contrary to the advice given by the guy I hired to help me take things apart; He used a flow meter and said the pump was ok. Here are some related data points. I have only been using the dozer for about a week.

I over filled the transmission to see if there were any leaks that could account for air being sucked in. After 40 gallons of over fill, I stopped, and the dozer ran fine. However after about 45 minutes, the converter temperature started heading in the red zone. I drained 20 gallons, and the dozer could run for 2 hours without the converter temperature getting hot. 2 hours is about all I can handle in a single stretch, so I was fairly happy until yesterday, for the 1st time, I pointed the dozer with the rear end down hill. Right after that, the dozer wouldn't move. I bled the air out of the transmission filter test port (the oil was filled with a lot of air) and haven't pointed the dozer in that direction since.

So, it sounds like when the dozer's rear end is pointed downhill, the pump may have to do more work and can't handle it. But I want to make sure there isn't something else I can try before handing over $3500 for a new pump. I am still wondering how much oil I would have to add to get it to overflow and if that would show signs of leakage anywhere.

Sounds like it stoped working once the oil got hot . Overfilling won't make any difference unless its operated on steep ground , there is a requirement to overfill by 20 % if the dozer is operated in that manner . Sooner you take the pump off and get it checked the sooner the dozer will e working again .

 

[nicky 68a]

Will have to change pump then.

 

[chriskarnaze]

I changed the transmission pump, and now it shifts when the dozer is pointing up hill, so the new pump made a difference. However, the loss of steering after pointing up hill remains. I didn't mention this earlier, because I thought it was related to the trasmission pump. I guess I need to replace the steering pump also.

 

[chriskarnaze]

I won't be replacing the steering pump any time soon. Komatsu wants $5900 for a pump that is the same size as the transmission pump ($3400). Can these pumps be rebuilt?

 

[epirbalex]

Its odd that you would have two pumps fail at the same time . There is a test port for the steering pump , 12.5 kg a cm .

 

[chriskarnaze]

They didn't just fail. I haven't been able to use the dozer since I bought it a year ago. It has probably taken the pumps 6 decades to wear to the point where they can only pump downhill.

 

[epirbalex]

They didn't just fail. I haven't been able to use the dozer since I bought it a year ago. It has probably taken the pumps 6 decades to wear to the point where they can only pump downhill.

re post 25 , thats a relief valve setting .Brakes work from off the same pump , their setting is 25 kg a cm .

 

[chriskarnaze]

I got the steering pump re-sealed and now the steering works pointing up hill. What a pain removing that pump. I was also able to remove the extra 10 gallons of trans oil. But the converter temperature gauge moves close to the red zone after 3 hours of heavy use. I have seen posts that say to check the oil cooler and that the brakes are not constantly engaged. Any other suggestions would be appreciated.

 

[epirbalex]

I got the steering pump re-sealed and now the steering works pointing up hill. What a pain removing that pump. I was also able to remove the extra 10 gallons of trans oil. But the converter temperature gauge moves close to the red zone after 3 hours of heavy use. I have seen posts that say to check the oil cooler and that the brakes are not constantly engaged. Any other suggestions would be appreciated.

Does it have a water temperature guage as well ? Both guages should track each other or close enough . When there is a difference showing between my temp guages there is a problem with too many small leaves in the radiator . Puff out or high flow water and all is well . Untill your radiator is clean it could be the problem , it looks like a small gain in cooling capicity might get hold of the issue , 3 hours is quite a long time . Good to see you are clocking up some hours with it .

 

[Simon C]

I got the steering pump re-sealed and now the steering works pointing up hill. What a pain removing that pump. I was also able to remove the extra 10 gallons of trans oil. But the converter temperature gauge moves close to the red zone after 3 hours of heavy use. I have seen posts that say to check the oil cooler and that the brakes are not constantly engaged. Any other suggestions would be appreciated.

Built 6 of those engines along with torque converters and transmissions. Its been a few years but the pumps if they were as old as you say were probably worn right out. When ever you want to restart those units make a rag ball and put it over the Transmission Filler pipe hole. You get someone else to put a 1/4 inch blow pipe into the filler neck with the rag ball on top. They can put steady air supply( About 1-2 PSI) into the tansmission sump . Make sure they don't go wild with the air and wear safety glasses. If they are putting too much air in they will feel it on the rag ball. So steady air pushes the oil up to the pump very quickly, but a worn out pump by-passes so much that nothing works. This technique also protects new pumps every time you change filters or change the oil. if the pump has oil pushed towards it at 1 psi it will pump instantly versus trying to suck oil. I have used this technique too many times to count. It will also, if all the oil is hot sometimes tell you with unit off where air is being sucked in as the pressurized oil will go to the escape hole on the suction side of any Pump. Hope this helps

 

[Simon C]

Built 6 of those engines along with torque converters and transmissions. Its been a few years but the pumps if they were as old as you say were probably worn right out. When ever you want to restart those units make a rag ball and put it over the Transmission Filler pipe hole. You get someone else to put a 1/4 inch blow pipe into the filler neck with the rag ball on top. They can put steady air supply( About 1-2 PSI) into the tansmission sump . Make sure they don't go wild with the air and wear safety glasses. If they are putting too much air in they will feel it on the rag ball. So steady air pushes the oil up to the pump very quickly, but a worn out pump by-passes so much that nothing works. This technique also protects new pumps every time you change filters or change the oil. if the pump has oil pushed towards it at 1 psi it will pump instantly versus trying to suck oil. I have used this technique too many times to count. It will also, if all the oil is hot sometimes tell you with unit off where air is being sucked in as the pressurized oil will go to the escape hole on the suction side of any Pump. Hope this helps

As Epirbalex said if your radiator is lime coated inside you will eventually get everything hot and need to have it cleaned or re-cored. If it lasted 3 hours you are not too far off from getting it perfect. Make sure your belts are good and that the rad is not oil soaked and 1/2 plugged up as I have often seen. Here is a picture of the last one I did complete. Hope this helps. Simon

 

[chriskarnaze]

The radiator temp gauge reads ok, so the converter temp gauge is not in line with it. I'll check the points raised above about the radiator. Thanks.

 

[epirbalex]

As Epirbalex said if your radiator is lime coated inside you will eventually get everything hot and need to have it cleaned or re-cored. If it lasted 3 hours you are not too far off from getting it perfect. Make sure your belts are good and that the rad is not oil soaked and 1/2 plugged up as I have often seen. Here is a picture of the last one I did complete. Hope this helps. Simon

Is that a S6D155 ? I can't make out the three heads on it along with the 3 tappit covers , nasty little place betwee them for all the twigs to sit and catch fire

 

[Simon C]

Is that a S6D155 ? I can't make out the three heads on it along with the 3 tappit covers , nasty little place betwee them for all the twigs to sit and catch fire

Yes it is a S6D155 Engine. They have way too many small pipes and lots of components to rebuild. Have seen every problem imaginable on them. They can push all day if done right.

 

[Horace Mace]

I had same problems in my 85a-18. In regards to not moving I resealed tranny and steering pumps and replaced all o rings and hoses on suction side of pumps. In hindsight I think tranny oil was aerated on the dipstick.
I have found slipping water pump belts and dirty radiator the most common causes of my heating.