Hey guys, Got a 631D with a 3408 engine overheating. Top radiator hose measures 110-120 degrees Celsius. But the bottom hose is back at 70 degrees Celsius. Engine is still overheating into the red and the top tank seems to be pressurised severely. Just had the radiator out and flushed at a radiator specialist. Symptoms seem to be worse than they were before. Any ideas?
i think the pressurization is the cause, need to find out why its doing that.
The temperatures at radiator inlet & outlet suggest low flow. Have you looked at the water pump.? A good next step would be to put 10psi or so into the cooling system with a pressurizing pump and see if it leaks down.
I have had the water pump off and it’s in good condition. Is it possible to get a pressure test kit for those old radiator caps?
Suspect pre-combustion chamber leak.
Don’t overlook the air compressor, I have seen a few put pressure in a cooling system. Just a thought.
Check that the sealing rubber around the fan shroud is in good condition and that it is fitting closely to the fan. Gaps here will result in reduced airflow through the core. Check that all pulleys are in good condition and not worn in the grooves, and allowing belt slippage. Is the thermostat (regulator) working properly? A thermostat that is not opening fully will slow coolant flow.