CAT 312 B excavator question

wally b · Jul 1, 2018

I have CAT 312 B excavator that I recently got. It is an awesome machine but a day or so ago I was digging out some stumps and the engine high temp light came on. All the coolant levels are good and the cooling fan is working good on the motor. I am wondering if I got it a bit warm because I was using the machine at lower RPM's (like at 1/4-1/3 full throttle) while doing heavier work as I am just learning on the machine. Does anyone have any suggestions as to the ideal RPMs for this work and any thoughts on the over temp issue? I used it for about 3 hrs this morning doing heavy digging of stumps without problems.

AJ. · Jul 1, 2018

All the operators that I come across usually run the excavator at full throttle but you should be able to use it at any RPM without it overheating,first thing to check is the radiator plugged up with dust,sometime the rads get plugged up with fine dust in between the fins,usually a good blow out from a site compressor will clear it out,stop the engine while you do it as you don't want to damage the rad or fan and make sure there is no debris that could get in the air stream and damage the rad,wishing you good luck with your investment.
AJ

newhollandnut · Jul 5, 2018

Blow out the radiator and if you can wash out the fins with a garden hose. You should really run it full throttle all the time. That is the rpm the the hydraulic are most efficient. Once cleaned out keep an eye on it. The thermostat might be sticking a little bit. My farm truck overheated pretty good this winter on the way to town. Ran by the parts store before going home and picked up a new thermostat and it is still sitting on the dash. Hasn?t even gotten warm since

NCWayne · Jul 5, 2018

Definitely run the engine at full throttle. If you think about it, the engine/fan speed is going to determine how much air is passing over both the radiator, as well as the hydraulic oil cooler. Too little air, and you'll create the conditions necessary for exactly what you're seeing.

That said, running the engine at low throttle actually doesn't gain you much of anything. Engine speed simply gives you the ability for x amount of HP, but you're only going to use as much HP as the pump calls for, regardless of speed/HP the engine is capable of. Kind of hard to describe how it all works, but I'm hoping you understand what I'm saying.

IanC · Jul 6, 2018

Cat (at least Michigan Cat) has excellent customer service for older machines. Go to your states Cat dealer with your serial number and they should be able to supply you with the access you need for the online parts books, and be able to get you an operators manual for your lube points and schedules. May even give you the history of your particular machine.

AJ. · Jul 6, 2018

That is very good advise IanC has given you,while I agree that excavators would be more productive working on full throttle the engine fitted is a variable speed engine and can be used at any RPM the operator desires,(that's why it's got a variable speed throttle) without it over heating,say for example you have to do a lot of lifting like placing steel or the like and would need to slow down the RPM of the engine to be able to go more gently you should be able to do it without it getting hot,that machine either has the Cat 3064 or 3054 engine which should have a plastic fan see that it is intact and the belts are good.
AJ

CAT 312 B excavator question

wally b

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AJ.

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newhollandnut

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NCWayne

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IanC

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AJ.

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