ex750-5 over heating problem change water pump,theromsart,flush out raditor new air filters need help.
Did you clean out the space between the radiator and hydraulic oil cooler. That's the first place I go. Usually there is nowhere for the debris to drop out to.
yes i did even install light fan with more blades it will work for a couple of hours an then tempture goes up
What year is your machine and how many hours do you have on it?
it a 2000 an the hours 9372 the engine was change but dont tink d hour meter was,i woud say they replace d engine about three years ago.
Don't want to be the one that tells you this but if you have done all you say it sounds like a cracked head.
there is no colant lost once tempture reaches up in red leave the machine at a idle it goes down put it back to work it goes up again
Are you loosing water ? I don't mean a visable external leak. Is the water just vanishing mysteriously without a trace. What color is is the exhaust ? Whiteish gray. bad. Sorry I did not see your response. we 'cris crossed'
no the water stay in d system an d exhaust is black when d machine load up then it clears right up
I have fought the same problem with a 700 Hitachi. I also know several others who have. It is pretty common for them in high ambient conditions. Here are a couple of things. 1) Hydraulic thermostats. They are somewhere between the tank and the cooler. I don't remember exactly where, but I do remember they are no fun. 2) Fuel pump not calibrated right. If it overfuels, it will smoke and make heat. 3) there is limited airflow passages to let the hot air out of the engine area. They plug easily, and the air is trapped near the engine, so it will not cool. 4) Exhaust leaks can let hot exhaust gasses back into the intake air, raising the temperature. I checked all the things you said, as well as all the ones I listed, and probably some more. I even louvered the hood on advice from someone. The most frustrating part was that every thing we checked had a problem, but when we fixed the problem, it still overheated. Thermostats were faulty, they would not open even in boiling water. Thought we found it, put new thermostats in, and same result. Pulled new thermostats out, and they opened at 180* just like they were supposed to. Sent the radiator and hydraulic cooler out, and sure enough, they werre plugged. Puth them back in all cleaned and tested, machine still heated just like before. Went through the same thing with the hydraulic thermostats. No change. Fuel pump was tested and found to be out of spec. It was rebuilt and calibrated. The machine ran better, but still overheated. It didn't matter what I did, after a few hours, it would hit 240*, and then would not cool below 220*. 10 minutes later it was back to 240*+++ Seen as high as 265*, and never lost the head or the gasket. I finally got frustrated and took the hood and side panels off, and left them off. Temp immediately dropped to 190*, and would go up to 210*-215*, and it would run all day. It was very frustrating, and a large sum of money was spent, when in the end the low tech fix of taking the hood off ?solved? the problem. I left the hood off untill we sold the machine. It went to Oregon, and I heard it didn't have any trouble there. Of course it rarely gets over 80* in Oregon. Good luck with yours.
I have run into another issue that involves the pumps taking too much horsepower out of the engine. Basically the pump control circuits are based on leak off of main pressure inside the pump control valves. As the valve gets older the leak off gets higher and the pump puts out a little more oil all the time. Operators get used to the increased speed and don't notice the difference until the pumps are reset to factory specs. Check the cycle times on the boom up function against factory specifications. Typically on most excavators they should be between 4.0 to 4.5 seconds with the stick and bucket extended and sitting on the ground to top out height. You can also check your fully loaded engine speed. Most excavators that I have worked on were set up to not loose more than 150 RPM with the stick out over relief. Fuel consumption will also increase but excavator work is not always continuous enough to show big differences. Good Luck!
tanks guys i will check on that hyduralic thermostat an cycle time to see what i come up with
One thing common on all Hitachi's is the foam around the rad and the bottom belly pan being missing. With a low pressure in front of the rad and a high pressure on the engine side the air will actually circle around the rad if the foam is missing. So what you get is the same air circling and heating up. If you look at the rad from the out side there should be NO way the air can get around the outside of the rad. Top bottom and sides. Refoaming the rad/cooler is something I have done plenty of times on numerous Hitachi's. While this may not be the only problem, it was always my first step.
Check your hydraulic filters. Is the hyd system operating okay? if the flow is low, it could cause the system to heat up. Also, you may want to check your case drain lines to make sure they are not plugged. This could cause the hyd pumps to build heat.
I had the same problem on my PC-120. Took the hood off to work on it easier and it never got hot again. Someone told me the seel between the radiator shrouds might be loose and allowing air to bypass the radiator. I plan to look into it further in the future but for now just having the hood off fixes the problem.
With every reply it reminds me of things we tried to fix the problem. Most were things that needed fixing, but they still never solved the problem till the hood came off. The 700 I had was a twin pump machine, and one thing there was making sure both pumps were matched. I am pretty sure the 750 is a single pump though.
I know lots of time up here even our machines get hot we prop the hoods up and they run alot cooler just lets that air move faster.
the hood is vented an i check the cycle time ,it not to far of from the 4.5 even d drop of rpm under load was close but there was some of the corking from around the raditor was missing so i replace it will run machine tomorow an c what i come up with.
tank for the help guy the machine is runing much better