Here's the scenario on a recent repair job for your consideration; Cat 365C, ELC prefix. Had the same operator for three years. Machine has always run with an ECT of around 85°C. Suddenly the temp jumps up to 102°C and almost puts the alarm on. Operator reports nothing out of the ordinary when he did his morning checks but machine now also seems a little down on power. Ambient temp is cooler than average for our area. Hyd temp is OK. Air filter is clean. Hydraulically driven fan speed is on spec. Delta temp across the radiator is around 8°C - acceptable. Radiator has recently been replaced and is clean externally. Has always had Cat ELC in it. Replaced ECT sensor - no change. Replaced thermostats - no change. Despite the lower power complaint, cycle times were on spec and main relief pressure was OK. Checked pilot pressure, a little low so adjusted to spec. Calibrated powershift PPC valve - no change. So it's now the end of the day and everyone goes home scratching their heads at the puzzle. However, go back to site the next day to continue working on it and the cause becomes immediately obvious. So, would anyone like to guess what the problem turned out to be?
Loose fan belt?
Fuel?
muffler blocked?
Yair . . . Spotted a bit of plastic/paper blocking radiator or vents? Cheers.
Some foreign object caught between the cabin and frame?
My first thought but it has a hydraulic fan.
That is about the best idea I can come up with or a kink in the exhaust stack out of muffler. Or dead bird in the intake!
Some joker reversed a couple of fan blades?
High temp + loss of power : something blocking the air intake ?
Oiler put gasoline in it? LOL
You mean "former oiler?"
Charge air cooler had something going on, or wastegate on turbo was stuck open/not functioning properly causing smoke (the "obvious" part)?
We arrived at the conclusion that the cooling system was working properly but something was causing the engine to make excess heat. In line with mark250's comment, we were all set the next day to check the muffler with a temp gun to check for big temperature differences indicating possibly a broken baffle blocking the exhaust. So what does every good mechanic do each morning before he starts working on a machine? He checks the fluid levels, that's what. And what does he find? He finds the engine oil level WAY overfull! We had to drain about 50L to get it down to the mark. The main hydraulic pump shaft seal had failed and filled the sump up with hydraulic oil. Now every engine I've come across with too much oil in the sump has symptoms like smoking, blowing oil out of the breather and even sometimes shooting the dipstick out of the tube. This one was running perfectly except, obviously, the crank was running in the oil, overheating it, getting rid of the heat via the oil cooler and pulling the ECT up. Also interesting to note that the extra effort of running the crank in the oil was sapping enough power to be noticeable in the cab.
Lucky really... I've seen engines begin to pull oil or oil/fuel mix through the crankcase breather into the intake... can't be shut down, clouds of smoke and screaming rpm's until she breaks or seizes....
Agreed. I was pretty surprised myself.
Komatsu had a problem with oil from the engine or a pump seal filling up the damper case box and basically making a hydraulic retarder. Those would get so hot it would burn the paint off the back of the engine and the damper case. Komatsu uses what looks like a clutch disk with no friction surfaces to drive their pumps instead of the elastic biscuit. They usually have about a pint of oil in the case to lube the springs in the drive disk. I recently saw a 345 Cat that was using the same system for driving the pumps. It might be something to look for in all the larger Cat excavators now days. Good heads up!
Years ago I was working for a bloke operating an excavator 7 days a week up to 4 months straight. So the boss got a relief operator in to give me a break. The first day back I was having lunch when the boss pulls up and roars at me for running the engine low on oil. So roared back that he better get up on the ***KN thing and check the oil now which he did. He then roars down to me that Iv'e over filled it. No ***kn way I says, thats what it was like when I checked on prestart this morning. He got the fitter out and we drained 10 litres of oil to get it back to the full mark on a sump that held 20 litres. The dipstick on that machine had to be pulled twice as the first reading was always incorrect. I figured the top of the stick would seal on the tube and not allow the oil back up. The boss and I became very good mates after that.