I have a friend that has a 1949 Chevrolet pick up he swapped a 1968 Buick 350 into it. He is an old hot rodder from way back, just using what was free at the time. My question is about overheating, He used all the parts he could off the Buick, except the radiator, it's new. All parts for the Buick engine are new, even the engine is a rebuilt engine. So, he has a 160 degree thermostat, the fan has a clutch and it's a 6 blade fan with a shroud. He has had the new radiator checked recently and is clear of any obstruction. At idle everything seems fine, it's at highway speed that the temperature creeps up to around 200. Any ideas?
jpletzer
Creeping up to 200 is not an issue, and in fact running at 200 degrees is good for the engine (it burns off moisture, etc.). Does the temp go higher than 200, or just level off there? Is the temp being measured with an electric or a mechanical gauge. Sending unit and gauge mismatch can be an issue with an electrical gauge.
Poor cooling at highway speeds usually means the radiator is too small or there is an issue with water flow. It has plenty of air flow at highway speeds, so that is usually not a problem with the fan, shroud, etc.
Poor cooling at highway speeds usually means the radiator is too small or there is an issue with water flow. It has plenty of air flow at highway speeds, so that is usually not a problem with the fan, shroud, etc.
At 16 PSI, the coolant won't start boiling until the temp is over 250. People lose a lot of sleep over this unnecessarily. Now if the temps continue to climb at highway speeds, that's an indication of an undersized radiator. If they stabilize, stop worrying about it. Other things to look at are vacuum advance and/or timing at those speeds. Insufficient advance will cause hot running conditions. Also look at part throttle A/F ratio. Lean mixtures also cause heat.
I personally would run a 195 stat and I wouldn't even blink unless it passed 235F.
Engine temperature is not the issue, it's when you have more heat going into the coolant than the radiator can remove. That's when temperature rises out of control. The engine is dealing with 2700 degree combustion events, so it doesn't care if the coolant is 200 or 500, as long as it's not boiling.
Engines like to be hot. Drivers like them to be cool, and they often go to great lengths to keep them icy... at the expense of engine health. My LS consistently runs 220F, and it keeps that same temperature regardless of if it's 10 degrees outside, or if I'm towing 7000 lbs uphill in the 110-degree desert at 5000 feet of elevation.
I had a Caddy 500 in a 78 dually running Evans NPG coolant. I frequently saw 300 degrees and it never batted an eyelash.
Engine temperature is not the issue, it's when you have more heat going into the coolant than the radiator can remove. That's when temperature rises out of control. The engine is dealing with 2700 degree combustion events, so it doesn't care if the coolant is 200 or 500, as long as it's not boiling.
Engines like to be hot. Drivers like them to be cool, and they often go to great lengths to keep them icy... at the expense of engine health. My LS consistently runs 220F, and it keeps that same temperature regardless of if it's 10 degrees outside, or if I'm towing 7000 lbs uphill in the 110-degree desert at 5000 feet of elevation.
I had a Caddy 500 in a 78 dually running Evans NPG coolant. I frequently saw 300 degrees and it never batted an eyelash.
Gets hot running down the highway speaks to a number of problems.
- The ignition advance is not coming up.
- The fuel mixture is lean.
- The cam was installed off time.
- Radiator is too small.
- Coolant flow isn’t keeping up.
Note a 160 thermostat is too cold, this should at least be 180 at the coolest. That said running 200 with a 160 thermostat on the highway but if it keeps 160 on a sustained idle its telling you something is amiss with cam or ignition timing, AFR, radiator sizing or coolant flow.
Yes, these days running 200 is how things come from the factory and isn't dangerous but looking at the thermostat opening temp and getting to 200 is a telegram that something is off.
Bogie
- The ignition advance is not coming up.
- The fuel mixture is lean.
- The cam was installed off time.
- Radiator is too small.
- Coolant flow isn’t keeping up.
Note a 160 thermostat is too cold, this should at least be 180 at the coolest. That said running 200 with a 160 thermostat on the highway but if it keeps 160 on a sustained idle its telling you something is amiss with cam or ignition timing, AFR, radiator sizing or coolant flow.
Yes, these days running 200 is how things come from the factory and isn't dangerous but looking at the thermostat opening temp and getting to 200 is a telegram that something is off.
Bogie
The factory Harrison radiator in this trucks will cool a big block. Most just need the core cleaned. What "new" radiator is in there now?
Loose the fan clutch
Measure air speed thru the radiator. Should be 35 ft/second minimum
Fan is not needed above 25 mph. So since the thing heats up on the highway, look at the things Bogie mentions
Loose the fan clutch
Measure air speed thru the radiator. Should be 35 ft/second minimum
Fan is not needed above 25 mph. So since the thing heats up on the highway, look at the things Bogie mentions
You probably won't like that 160 t-stat in the winter. Also, your engine won't be able to burn off condensation in the crankcase. I'd go with 180 or 195.
Could be radiator size, but could be flow issues either in the water pump, or internally in the engine.
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