My question is my engine is getting hot then cools down then heats up again. I changed the water pump, thermostat, same

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Customer: My question is my engine is getting hot then cools down then heats up again. I changed the water pump, thermostat, same problem. Water is being pumped into the overflow bottle. Checked for exhuast in the coolent, came out negative. Having the radiator rodded, but the shop says the radiator was only 25 percent clogged and doesnt think it was really a problem. So now im wondering if there is an internal problem
Answered by KevinB in 1 min 14 years ago
6+ years of experience

158 satisfied customers

Specialities include: Auto Body Technician, Heavy Equipment Repairs, Diesel Engine Repairs, Brake and Transmission Repairs

What type of engine are we dealing with?
6.7 diesel in a 624h john deere loader

How did this problem develop? Was it gradual or all at once?

It happen all at once, was running fine then next day is when I noticed it was getting hot
Does your hydraulic fan seem to be spinning at the correct rpm?
The spec for the the fan is 510 rpm at idle and 1200-1300 rpm at high idle
Yes Fan is spinning at correct rpm. To assist you some more, the temp. goes from about 188 to 220, then back to 190, then back up again, and so on. If you keep the rpm's up seems to keep "cool" When you stop then is climbs up to 220 and higher. You give it throttle cools down. Almost sounds like a thermostat.
Does your engine have an electronic fuel system or mechanical?
Did your engine have a insert for the water pump? Was the water pump you replace faulty?
Believe its mechanical, had to put an insert in when I purchased the new water pump. Water pump is working its blowing water out of the coolent overflow bottle. Upper hose is warm to hot, lower hose is cold. One heater hose is hot other is cold, and the block is warm to hot to the touch. Weak heater output as well
If your lower radiator hose is cold and the top hose is hot that tells me your thermostat is working it is letting the coolant get to the radiator. With the lower hose being cold that leads me to believe the radiator is plugged you should not have a temperature drop of that much it means that the coolant is being restricted in the radiator, slowing the flow so that it cannot cool the engine. The sudden drop in temp is more than likely due to the fact the water pump is cavitating because the coolant flow to it is restricted. This is also why the heater is not putting out heat due to a low flow condition. I would get the radiator rodded and retest I feel that will cure your problem. I've been down the same road with radiator shops what they are telling you is a estimate and these cooling systems are sensitive to cooling restrictions due to the fact they don't have a very high capacity water pump.
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158 satisfied customers
6+ years of experience
6+ years of experience

158 satisfied customers



Licensed mechanics

31,131 satisfied customers

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Last Updated: 12-20-22
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