I have a 28 hp Komatsu min excavator and it runs fine until about 30-40 minutes of using the front bucket the coolant temperature rises to 240. Under no load it does not overheat. I just purchased it, and previous owner did not use it as much. It sounds like a hydraulic issue. I have not done much troubleshooting other than flushing the radiator and removing the thermostat as well as replacing the hydraulic oil filter. Temperature still gradually rises when using the hydraulics after 40 minutes or so of use. My next check will be the hydraulic oil cooler and possibly replace the water pump. Anyone has any other idea on what else to check? Any feedback is much appreciated.
-
Thank you for visiting HeavyEquipmentForums.com! Our objective is to provide industry professionals a place to gather to exchange questions, answers and ideas. We welcome you to register using the "Register" icon at the top of the page. We'd appreciate any help you can offer in spreading the word of our new site. The more members that join, the bigger resource for all to enjoy. Thank you!
PC27R-8 Komatsu overheats when using bucket/hydraulics
- Thread starter Samborosy
- Start date
Simon C
Senior Member
- Joined
- Jul 1, 2015
- Messages
- 3,008
- Location
- Rocky Mountain House , AB., Canada
- Occupation
- Heavy Equipment Mechanic
You need to do a little more diagnostics before buying any more parts. Has the outside of rad been totally cleaned. Have you checked to make sure there is a good difference between the top and bottom rad hose temperature. Did you remove the thermostat and leave it out.?
Is there any foam missing around the rad for sealing. Is there some 60/40 antifreeze mix in it?
Not there so just asking.
Simon C
Is there any foam missing around the rad for sealing. Is there some 60/40 antifreeze mix in it?
Not there so just asking.
Simon C
Gary Layton
Senior Member
See post #49 here...my CAT 320C had overheat problems, too.
Going to do more troubleshootig this weekend. I did remove the thermostat but will reinstall it.It looks new and is working. Radiator looks clean on the outside. It seems like when i pull the cap off the radiator i do not see much water movement even with the thermostat removed when i start it. Water pump looks new but machine has been sitting for a good while according to the previous owner. Engine sounds good and can run it without a load and will not overheat. Once i start using the bucket it takes about 40 min then tempature starts to rise to 230-240 and hydraulic filter housing is hot. Thanks for all the feedback. I will keep troubleshooting. Upper rad hose is pretty warm and bottom is just slightly cooler. I will get a temp gun this weekend.
Simon C
Senior Member
- Joined
- Jul 1, 2015
- Messages
- 3,008
- Location
- Rocky Mountain House , AB., Canada
- Occupation
- Heavy Equipment Mechanic
Water does not have even close to the same boiling point as antifreeze. That rad has to be clean all the way into the corners with day light going through everywhere. Need to do accurate test of temperature of top to bottom rad hose. Does the unit make any smoke that is different.Does it have some good engine oil. Is the hydraulic tank full.
Simon C
DustAndRay
Active Member
That's a really big clue when you say you don't see much water moving in the radiator, even with the thermostat out. I think you're getting real close to finding the problem. That points right to the water pump, just like you were thinking. Sometimes, even if a pump looks new on the outside, the little spinner part inside can break or get corroded from sitting for a long time. So the belt will turn the pump, but it's not actually pushing any water. That temp gun you're getting is a great idea. It will tell you for sure if the water is getting cooled by the radiator. Good luck this weekend! Hope you get it figured out.
Thanks, I did verify that the water pump is working.
I reinstalled the thermostat and refilled with antifreeze. Rinsed out the radiator and hydraulic oil cooler from the outside. Ran it and used the bucket and never got hot. Was staying at around 160-180ish. However, when I started to use the hydraulic thumb, the temperature started rising. I can actually move (push)the thumb by hand in the open position. I believe it may have a leaking cylinder ram on the thumb which is causing it to overheat. I should not be able to push the ram in is my guess. It's hard to actually grab anything with the thumb and bucket since the thumb is weak on pressure. Will look into rebuilding the ram since the O-ring/seal kit is not too high. It could also be a relief valve. I will keep troubleshooting but at least we can use the bucket without it overheating.
Thanks for all the feedback!
Simon C
Senior Member
- Joined
- Jul 1, 2015
- Messages
- 3,008
- Location
- Rocky Mountain House , AB., Canada
- Occupation
- Heavy Equipment Mechanic
Thumb cylinder is easy to test in case there is nothing wrong with it, and test costs nothing.
Make the rod extend and when it gets to the end of stroke disconnect the hose at the packing end. If you try to extend more with the hose disconnected, any oil coming out the packing end fitting is by-passing oil. Do it with it revved up some and hold for 5 sec., or until you confirm if packing is gone or not. If it is not leaking you most likely have a valve problem or relief problem causing oil to heat.
Try that simple test first.
Simon C
farrellapparel
Member
Did you get your overheating problem resolved?
Simon C
Senior Member
- Joined
- Jul 1, 2015
- Messages
- 3,008
- Location
- Rocky Mountain House , AB., Canada
- Occupation
- Heavy Equipment Mechanic
Have you checked with a heat gun, that hot would be too hot to touch pipe from thermostat out to radiator.
Simon C