I've got a 250 6 cyl in my 50 chevy Low mileage.used engine,new v8 radiator,pusher electric fan it will idle at 190 all day long,get on the highway and it heats up.Flushed the cooling system several times still did it. Pulled the thermostat no help.WTF!!
First, what is "heats up"? A number..and does it keep climbing, or settle at one temp? The pusher fan may be blocking airflow at highway speeds. also if you could post a few pictures of the engine bay, from a few different angles, maybe we can see something obvious that you can't.
LOL none of them will make the heater work @ 60 below. I am kind of in agreement with Squirrel on this subject. One question that he didn't address is this a new development or????? Also the rebuilt water pump that was installed to save money may not be pumping water just agitating it. When you open the radiator do you see a good water flow?
Timing that is retarded is a common problem with these causing overheating. 6-10 set at idle with no vacuum line hooked up. plug vacuum line to a manifold port and then idle it back down. Also check the vacuum can for proper operation.
Could be a partially plugged radiator. Had a similar problem and it turned out, mice built a nest in the top tank over the winter.
It's not a "1-piece head" 250" engine, is it?? If so, the heads are known to crack. I had one in my old '80 C/10. You can install a regular "3-piece head" on it if that is what you have. pdq67
4 degees advanced or 4 degrees retarded? Late timing is a definite cause of overheating at highway speeds. With no thermostat the coolant could be flowing through the system too fast. Removing it all together doesn't always help the engine cool no matter what the spit and whittle club says down at the corner station. t Less than stellar water pump blades not moving the coolant, that could be. I don't think they ever built a straight six Chevy with a serpentine belt so that idea is out. Unless you either bought some serpentine belt kit or cobbled one together without a reverse rotation pump rotor. I've dealt with two engine swap V8 cars that had the wrong pump for the belt setup and both acted exactly like what you are seeing. Cools at an idle and overheats at road speed. I'm wanting to think timing or a serous blockage of air through the radiator at road speed for one reason or another. My truck with the 250 in it did the exact opposite. 183 degrees down the road with a 180 stat and the temp climbed to 220+ at an idle in traffic and dropped as soon as the truck got over 25 mph. One thing that just came to mind. Is the electric fan moving air in the right direction? Is it pushing cool air though the radiator at an idle or pulling air out through the grill at an idle? It may be moving air in the wrong direction and fighting air flow on the road.
I agree with this. We covered the radiators with cardboard and used a 195 thermostat in tri-five Chevys. We even took the fan blades off the water pump. Have you checked the radiator in and out temperatures?
Doesn't it lack power at 4 degrees. Is that 4 degrees with the vacuum advance disconnected? Maybe it's running too lean. Gas these days isn't like gas in the 50s and it might need more fuel.
Ok,checking it again.Radiator cap off,rev it up and coolant comes up out of the radiator.Blown head gasket?
OP said - "get on the highway and it heats up." Manifold or "ported" vacuum advance is the same once the throttle is open a tiny bit, so the contribution of Vac advance on the highway would be the same.
Looks like the advance is working.Timed it again to about 8 degrees.I'll drive it again to see what happens.
It's putting coolant into the radiator faster than it can flow through. Plugged radiator or collapsed lower hose is what I'd look for first.
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