850j

I have an 850j that keeps overheating. SN T0850JX143077, we have fixed the exhaust leak it had, changed out the thermostats, verified that the radiator is not clogged. Preformed the fan motor test and it passed. Have verified solenoids are within range, verified no exhaust in the coolant, water pump is working properly, no coolant in oil. What else I’m I missing? We are going to perform the fan speed test in the morning, and we have no way of performing the flow test on the pump. Before I order the pump just wanted to make sure I am not missing anything. Thanks in advance

Is it overheating on the display or with a temperature gun taking temperatures. Could a engine oil cooler be partially plugged and causing it to get warmer. Could the transmission cooler be partially blocked and causing more heat.
Is there foam seals missing around the radiator, have you checked the temperature in versus out on the radiator hoses.
What kind of oil is in the transmission, hydraulics and engine. Is something stuck over relief and causing the heat, like a by-passing cylinder.
How hot is it on the day it is getting too hot.
Have you temperature gun checked things to see if you find something else that is hot.
Simon C

Robert Rdz said:

What else I’m I missing? We are going to perform the fan speed test in the morning,

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Verified with a temp gun to eliminate a bad sensor? If the radiator core is clean, then a fan speed test is. Make sure the test is performed as stated in the Operation and Test manual (1450 rpm minimum with the transmission oil temp at 135*-150*F ).

Ok we verified the sensor, fan speed was at 1600 rpms. Verified temperature in radiator and no cold spots so we are thinking that’s not clogged. Going to replace the water pump to see if that helps it. Anything else we might be missing?

How's the condition of the coolant? Strong mix can hold heat adding a gallon water to thin it out may help.

Check the radiator core again. If you had an exhaust leak the fins could have a film of soot on them that could cause the coolant to overheat. I've had a couple I could see through core and had air flow but still wouldn't cool. If that's the case you'll have to clean it with a hot water pressure washer, blowing through it with compressed air won't remove the soot.

Measuring temperature drop across the radiator can help determine if the issue is air flow or coolant flow.

Robert Rdz said:

Ok we verified the sensor, fan speed was at 1600 rpms. Verified temperature in radiator and no cold spots so we are thinking that’s not clogged.

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What was the temp at the top versus the bottom? You just say "no cold spots", that doesn't mean anything. I'm going to assume that you saw a small difference, since you didn't notice anything out of the ordinary. That could be a coolant flow issue, but it also could very well be the radiator is clogged internally or externally. You need to retest your temps, several times from soon after startup until it gets hot, and post the results.