We just put a rebuilt injector pump and injectors on the machine to cure a rough running condition. It now runs great but I noticed after about 2 hours of pretty hard running the temperature was really high. Just below where the alarm would go off. The motor was noticeably warm and the engine cover was hot. It cooled down some after idling for a bit but went back to the very upper end of the temp range pretty quickly. So drove it to the shop and let it cool down overnight. The next am I figured would blow out the radiator and figure it out. Noticed the coolant overflow tank was black and has black oily substance in it. Took cap off the radiator and black stuff floating around in there. So my question is how to diagnose from here? My thinking is that the oil cooler has failed and is putting oil in the coolant. So we could change that somewhat easily but would that cause the running warm situation? How would you guys proceed on this one?
Did you confirm temperature with an infrared temperature gun at the thermostat housing? Shoot top and bottom of radiator for a temperature difference? Are there bubbles in the coolant overflow when the engine is running? Maybe run the overflow hose into a bottle of water to watch for bubbles. If it is oil and not soot in the coolant, then yes it could be the cooler. Could also be liner pitting or head gasket as well. Is there any coolant in the oil? Let sit overnight and crack the engine oil drain plug to see what comes out. Perform an oil sample? Does the engine have a lot of hours? What coolant are you using? So many questions and so little time.....
Thanks for the reply. Did not check temperature but I couldn't hold my hand on the hood prop and that isn't normal. Smelled warmer than usual when I got out and poked around too. There were no bubbles in the coolant with the radiator cap off after about 2 or 3 minutes but may not have let run long enough. We didn't see any coolant in the oil but may need to let it sit longer and try again. Engine has about 5,200 hours. We do get oil samples on it when we change it and have not had anything out of the ordinary but only run enough hours to change about once a year so it may have been several months since changed. We generally use Oreilly universal coolant. I've about made up my mind to take off the oil cooler. Seems like it won't be "too" bad to get off. Nothing is really easy to work on the engine here though. Not sure where else to start.
I just did a jd 210 with the same oily residue in the recovery tank. Mine was the head gasket but you should eliminate other causes before you go that route
That would be the incorrect coolant. Does not have the additives to prevent liner cavitation.
If you take off the cooler, the cooler itself will most likely be OK. Still pressure test it to be sure (while the whole thing is still assembled). Concentrate on the O-rings that seal the cooler to the housing. Also check the machining of the O-ring grooves. We have had some issues there. If you decide to replace any parts buy the whole cooler assembly. The new housing will be cast iron instead of aluminum.