I am having trouble with a 1999 komatsu PC 400 with a Lebounty cutting head on it.The machine has a brand new engine installed by komatsu dealer,and a new radiator. The machine runs ok at first but will over heat after about 15 mins of hard use.Also when it starts getting hot the hydraulics start moving slower and slower.We have a manual gauge that reads around 185 degrees Fahrenheit,but o the actual monitor of the machine it reads between 7-9 bars on the temperature.when the bars go up the controls get slower and slower.Could this be a sensor? oil over fill on a component? crossed or backwards hoses? i am an operator and my mechanic hasn't been much help.Any feedback greatly appreciated.
My first impression/thought, is this set up for a cutting head. A friend of mine put a cutting head on his PC300 and it ran hot, after about 1 hr of work. Then the hydraulics would start working slow He replaced a bunch of parts and he finally installed an external hydraulic radiator, with a coolant fan. It was a big unit and he mounted it on the outside, with a guard. This was a while back, but I think he got this cooler and fan off of a bigger excavator and plumbed it in line with the original cooler. I dont know bars, but 185 degrees is not hot, get a temp gun and check the temp of the engine and hydraulic fluid, if everything is working normal they should be about the same. Remember, if the hydraulics are working to hard, it will cause the temps to go up, which sends a signal to the computer "Hey, slow me down, Im dieing here" Have you cleaned the radiator and hydraulic cooler? The mulching machine I used to have, required cleaning out at least twice a day. I used air pressure. It was a Fecon machine and Fecon, had installed and external coolant package, when they used the mulching head (external cooler, with a hyd driven fan)
Thanks,and good point i think i will use a temp gun and make sure it is hot when the bars say it is hot so i know if it is in fact over heating or not.
Komatsu excavators monitor the engine coolant temperature and derate the pumps when that temperature reaches a certain point. As I recall it was somewhere in the area of 210 degrees F. but I could be wrong easy enough. The system will put the engine back at idle if it get hot enough. I have seen hoses hooked up wrong from the valve to the pump. You don't mention the Dash series of your machine but I'm guessing that it is a Dash 6. I don't remember for sure but there might be two jet sensor hoses coming from each valve and hooking into each pump. I've seen those hooked up backwards or even on the wrong pump. That might be loading the pumps all the time. You might also check the oil level in the damper case to make sure it isn't completely full of oil. Finally I've found more plugged radiators causing heating problems than anything else. An infrared thermometer is a must now days. You should have at least 15 degrees difference between the thermostat housing and the water pump inlet. Good Luck!
Komatsu excavators have an intelligent hydraulic system that is so complicated it requires a real good dealer mechanic for troubleshooting. These things are not simple, there are numerous valves in the control valve that can cause heat buildup. Attachments can cause issues if the machine is not setup for them. If you are top-notch in hydraulics and have a manual, check the system carefully to make sure everything meets specs. Trust me in this, we have 3 Komatsu's and the older machines will develop overheating issues and 9 times out of 10, it's caused by the worn components in the hydraulic valving. If you aren't well versed in hydraulics, call Komatsu and get a guy out there before something gets damaged, those control valves are huge dollars, about the same price as an engine. Hopefully it will be something simple, but ya just never know these days. Good luck! Mike
ok guys thanks for all of the help,now we have confirmed it is actually over heating. The hydraulic pump was tested and pumped perfect on the high and low pressure test.with the hood in the up position, this machine will run fine, as soon as you shut the hood and continue using it, the temp will go right back up.
Is the fan OK Have you cleaned out the hyd cooler and radiator, with air pressure. Im not sure on the 400, but sometimes you can pull the coolers off the front of the radiator, so you can clean them out separately, without disconnecting lines/hoses I did have a PC300, that I had to pull the radiator and have it cleaned out, it wasnt flowing enough water I think its time to call Komastu and have them come out and check the machine Good Luck, keep us poasted
This machine has a brand new radiator and we frequently clean the hydro cooler with air pressure.And we have even had a local komatsu dealer come out several times,the guy just gives us a list of things he thinks it could be,we replace the small sensors and such he tells us but, the problem continues.
One commonly overlooked item is the sponge rubber inside the hood, its located to sit down on top of the radiator area. It's there to stop the airwash from the fan recirculating the hot air back to the inlet side of the radiator. We have had several machines lose this from steam cleaning etc. Seems like a small item, but can cause overheating if it's not in place. There is all kinds of ventilation for air to reach the radiator, but if you look you'll notice not alot of places for it to go after it comes through. Belly pans have small vents, usually not a lot of room between the engine and pumps for air flow, all this can cause a bit of backpressure, and if theres nothing to prevent the hot air from getting back to the inlet side of the radiator, it can cause heat buildup. Hopefully it'll be something minor.
Just to make sure here, is it only the hyd system that is overheating? what temp? Those sponge baffels MJR mentioned are critical to get airflow going to the right places. Depending who installed this attachment, it may not have been done right. Newer machines are capable of producing reduced flow to dedicated attachments when they are selected. This protects the machine and the attachment. Who installed this on your machine. Hope this helps. Later Bob