Re: Packard model 2365, 288 cubic inch engine running hot

Posted by Fish'n Jim On 2015/6/8 9:30:56
"Hot" or "higher" is forcing more heat out, so in effect it's a good thing, up until it effects the lubrication and other aspects like fuel delivery, etc. So if it's just a few degrees higher in the hot weather, idling, I'd not worry unless you want a perfect running original. The seven psi cap will take around 215-220F. It's counter intuitive but DO NOT use a lower temp. thermostat.
The real issue is are one or more local areas "really hot" due to restrictions. A thermal scan may indicate that. Nothing less than "boiling out" the block would accomplish "factory" heat transfer performance.
If you aggressively try to clean the water jacket, you open up the possibility of leaks, etc. I'd just repeat the drain and system flush a few more times and take what I got. The issue is not to transfer junk from the motor to the radiator where the passages are smaller, so disconnect the hoses/separate. These motors are hard to flush and reversing the flow can't hurt. I stuck a hose nozzle down the thermostat hole as Owen suggests and reverse flushed mine.
Is the hood/bonnet up during this time? It's designed to take air in the front through the radiator and opening the hood can short circuit the fan.
If it doesn't cool down after it's moving then I'd go further with disassembly. A fan shroud might help increasing air flow at idle. They didn't come about until later. These motors turn rather slow at idle compared to most so a low speed open fan is not an effective air mover to begin with. Is it idling too fast? After I got it running, my 2365 would idle in the drive at 400 rpm almost indefinitely and not heat up.
Double check the water pump is functioning correctly, etc.
Also what oil are you using? Some put higher viscosity modern oils in older motors and they weren't designed for that. That increases viscous "friction" which means heat.
Another more exotic solution may be to use one of these new high heat transfer radiator liquids, but no experience in these motors, but have used elsewhere.

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