Running hot 65 Dart

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williaml

williaml

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I bought a 65 Dart 3 years ago. When I purchased the car it had a 69 225 6 cylinder in the car that ran great. I also received the 65 225 6 cylinder engine. I wanted to restore the car back with the matching numbers or series in that time. The guy I purchased it off said the 65 engine ran but overheated and that is why he swapped the engine out. I had the 65 engine rebuilt and re-installed in the car. Since the rebuild I have only probably 1000 miles on it if that. The gauge shows it is running hot, the gauge will pin all the way over to the extreme right. The coolant never boils out. I have had the radiator checked and it came back fine. I've changed the thermostat to what the manuals indicate it should be. I've order a temperature gun and an auxiliary temp gauge to see if it is the engine or if it is the gauge. The engine re-builder is claiming it isn't the engine as they boil the blocks or such....any clues on why the running hot? Is the coolant strictly through the head and threw the pump and radiator or does this engine have coolant tunnels throughout the block? what should be the reading when I shoot the thermostat housing?

This forum is great as well as all the people who answer.

Thank you who read and advise.
 
Once and only once I had a slant water pump that the impeller was loose on the shaft.The bearing was good and didn't leak.Would run hot when driving and warmer that it should at idle.Just a idea. As far as your questions,Yes the block has coolant passages.Depending on your thermostat the temp gun should read within a few degrees of what your thermostat is.Lets say a 180*, at 180 the thermostat will BEGIN to open and should be fully open within 5*. So at Idle a reading of 185-190* should be normal.It may be more if the car has air.Other than that some other things such as timing,tune etc.also plays into the game.
 
The first thing I thought when I read this was, The temp gauge pegs to the right when? As soon as it starts? After driving? How long? At idle? On the highway at 200 mph? Stays right always or intermittent.

I, being lazy, have found it is a lot less work to think about how the system operates, then determine what fault can cause the symptom displayed, rather than jump around checking things at random.

The first thing you need to know is whether your gauge is lying to you. Remember, when you check the temperature at the thermostat housing you only see what passes the thermostat. I prefer to check the temperature at the engine outlet for the heater hose, since there is coolant flow constantly. This assumes there is no heater control valve, or if there is it is open.

If you get to the point you suspect the water pump is not pumping you can test that without removing it. Connect a flush tee fitting in the heater hose from the engine and adapt a pressure gauge to it. When you raise the engine speed you should see 10 to 15 lbs. of pressure, I would think. This assumes a thermostat is in place, as it should be.
 
If only the gauge is saying it is hot time to take it's temp elsewhere. Same sending unit that came with the engine? Can you swap sending units?
 
You can also buy a radiator cap w/ built-in temperature gage on ebay. Haven't tried one. My Harbor Freight IR gun was amazingly accurate when I did tests to confirm the dash gage and T-stat in my M-B, both in-car and in a pot of hot water.
 
How did it run with the other 225 in it? Did that same gauge show it was hot?
 
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