Need advice to troubleshoot overheating engine

I bought a 1961 Volvo PV544 three years ago and have had constant difficulty with the engine over heating, especially when going up hill. I have taken the car to five mechanics. None can find any problem with the engine. The following work has been done: Radiator was flushed out; Cracked radiator hose replaced; Thermostat removed as suggested by two mechanics. New spark plug cables installed; Engine has been tuned. The last mechanic said it was common for the thermometer gauge to go past "H" when the engine is turned off. Cracked head gasket was replaced.
Here are other symptoms that could indicate a problem somewhere else: When the engine over heats, when going up hill; it feels like I am hauling a heavy load behind me. The engine starts to lose power. I have to shift down to fourth or third gear. The speed drops down to twenty five. The needle of the thermometer goes past "H" and disappears. When I start going down hill, the speed will pick up to about 45 or 50. The needle on the thermometer then returns to near vertical and within the "save" zone. The needle starts to creep up as I come to level roads. When the engine is hot, one brake tends to freeze as if it wants to stop the wheel completely. There is some grinding sound when I shift into fifth gear.
Possible causes could be either the transmission or a brake the is too tight. Another symptom is that the car does not roll freely, with gravity,
when on a slight down hill slope. The car starts to slow down and almost stop as if a hand brake or another brake is on. This happens with the engine in neutral and no foot on the brakes. I would appreciate any tips, suggestions or know solutions to this problem. From Will

Losing power is due to the heat.

Have you double checked you HG since you've had it replaced? Are you losing any coolant or mixing coolant and oil? If one of you're brakes were engaged all the time, you should smell the pad burning and the wheel will be very hot but shouldn't be dragging the engine where it would overheat and lose power as you're dragging brake will get hot and lose grip.

I would go through the motor again.

Welcome to the forum!

WillH wrote:The last mechanic said it was common for the thermometer gauge to go past "H" when the engine is turned off.

The factory temp gauge is some kind of non-powered mechanical gauge - I forget what they call it exactly - and the sender bulb heat soaks when the car's off, which sends the needle to the high side. So yeah, that'll happen.

I have to shift down to fourth or third gear.

There is some grinding sound when I shift into fifth gear.

Do you have some kind of transmission swap? I thought there was only the M40 4-speed in the PVs, and even the M41 is an electric OD, not a true 5-speed. I'm curious as to what else has been modified on the car.

As to the actual overheating issue - I know you said the engine's been tuned, but tuned how? The ignition timing might be off. Also, what grade of gas do you run? I'm still learning about the pushrod Volvo engines, but I know they were built to run on high octane leaded gas, so that could affect the timing setting, which could in turn contribute to an overheating issue.

Another symptom is that the car does not roll freely, with gravity, when on a slight down hill slope. The car starts to slow down and almost stop as if a hand brake or another brake is on. This happens with the engine in neutral and no foot on the brakes. I would appreciate any tips, suggestions or know solutions to this problem. From Will

This definitely sounds like a dragging brake to me. Does the car pull to one side? Do you smell brakes after the car's been driven?

Has this ever been solved????

Shame

Codum wrote:Shame

Isn't it?