Good MorningI service a pair of Cat 3512 generators 1,250Kw 277/480Vac 1,880 Max Amps capacity. One overheated during a power outage. We replaced the drive belts, tested the radiator pressure, installed a new water pump, new thermostats and added new coolant. The radiator was pressure washed and is not damaged or corroded, we also inspected the turbos and the cylinders with a heat gun (no problems detected). The generator now works with loads of up to 1,000amps; when loads are increased to 1,200amp it overheats in minutes. We tested both generators and the air flow from the radiator does not feel as strong as the hard as the not overheating. What do you suggest I inspect? Thanks you.
Make: Cat 3512 Generator
Engine: Cat 3512
Hi. Thanks for using JA! I will try and help you out.I suspect you have an internal restriction in the radiator. I have seen this before. Your condition is known as overheating at high loads. Basically at 1000 amps the radiator is sufficient. But when you go up to 1200, the load is too much. To test for an internal restriction, you should check the temp at the top and bottom of the radiator. I'd there is a big diffeerence in temperatures, it is internally restricted.Please reply back if you need more help or have more questions.
Thank youWe also inspected and the temp is 185 on top 170 in the bottom.
You are very welcome. Was that the temperatures when the engine was overheating?
That was the temp when not over heating, with the loads at 1,000amps. The max engine temp at 1,200amp was 195 and we shut down a chiller hand stabilized it again at 1,000Amps and 185 degrees. I will test it again with the entire load up and test the radiator temp. By your experience what temp difference do you think I might have.
Thanks for the information.Its best to check the temp when it is overheating. Checking the temps when it is not overheating will not show anything. The temp difference when not over heating can be a lot,, like around 15 degrees.When under full load, the temp difference from top to bottom should be 8 to 11 degrees. If it is greater, there is a flow problem in the system. Since you have replaced the thermostat and wp, I would suspect the rad is restricted.
23 Years Caterpillar Engine experience.