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DFWAVL

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Only driven my 40 flathead a couple times since I got it from my brother, he passed last Apr.
It gets hot, one water pump was leaking, I replaced both, carb was clogged, ran lean, rebuilt that now it's still running 210° at idle, both hoses are about the same temp, new radiator cap from Carpenter.....not sure what to do next....?
 
How are you determining the temp. T/stats?? If you touch the radiator at the top mand the bottom, is the bottom cooler??
Radiator could be plugged.
Paul in CT
 
Some thoughts....is the temperature gauge accurate? Timing set correctly? Thermostats working correctly? Sufficient air flow through the radiator? Is there a fan shroud on the radiator? If these things check out, flush the cooling system to remove any sediment that could be blocking radiator flow or heat transfer from the block.
Good luck!
 
try on of those laser thermometers. you can check the radiator to see if it is cooling.

You may get different readings all over but as long as they are under 200, it does not make too much difference
 
31, that could be my issue with the 48 Merc 59AB. Finally found a temp sensor that worked after changing both water pumps. Have old 180 in there and temp gage goes 3/4 then higher on idle. I understand 160 stats send gage to 1/2 if cooling system OK. Car has 2000 miles on total rebuilt engine, bored +60 in 1975. Did notice recently that radiator is hot at top and NOT hot at lower hoses. I'm flushing with Thermo-cure and installing 160s. If that doesn't do it.... I'm in trouble. This is a 990 point Dearborn car. Anybody wanna jump in on this?
 
Retarded spark will aggravate overheating. You might try advancing the spark one mark at a time until you get pinging while accelerating in second gear or going up a hill. Then back off one mark.

Also, modern antifreeze does not cool as well as plain water. You need some antifreeze for anti-corrosion and water pump lube, but you could cut the mix from 50% to 20% (one gallon antifreeze with four gallons water). And put in a water-wetter.
 
Dunk said:
31, that could be my issue with the 48 Merc 59AB. Finally found a temp sensor that worked after changing both water pumps. Have old 180 in there and temp gage goes 3/4 then higher on idle. I understand 160 stats send gage to 1/2 if cooling system OK. Car has 2000 miles on total rebuilt engine, bored +60 in 1975. Did notice recently that radiator is hot at top and NOT hot at lower hoses. I'm flushing with Thermo-cure and installing 160s. If that doesn't do it.... I'm in trouble. This is a 990 point Dearborn car. Anybody wanna jump in on this?
Click to expand...
Installing 160degree stats will not make it run cooler. If it's running hot any temp stat is going to be wide open.
 
If this car has sat for a long time I suspect the radiator could be plugged. Drain the coolant down where you can see the tubes inside and see if you see any crud in them. Cars that sit for a long time and not run can be the victims of electrolysis. It plugs the radiator tubes.
 
Dunk said:
31, that could be my issue with the 48 Merc 59AB. Finally found a temp sensor that worked after changing both water pumps. Have old 180 in there and temp gage goes 3/4 then higher on idle. I understand 160 stats send gage to 1/2 if cooling system OK. Car has 2000 miles on total rebuilt engine, bored +60 in 1975. Did notice recently that radiator is hot at top and NOT hot at lower hoses. I'm flushing with Thermo-cure and installing 160s. If that doesn't do it.... I'm in trouble. This is a 990 point Dearborn car. Anybody wanna jump in on this?
Click to expand...

I would not change the thermostats, unless they are hanging up (not opening).
It is very unlikely they are the issue. Thermostats determine the lower end of the operating temperature (in this case 180) not the upper range. That is determined by a lot of factors listed in previous post.
 
You are probably correct. Today, dumped in 2 bottles Thermo-cure with thermostats OUT. Ran it several hours and it never got above the half mark... IR tester 160 to 180 both sides hoses, block and radiator full scope. Probably had some gook in radiator preventing or slowing flow from bottom to top. HOWEVER.. the two 180 stats were full of crud and crusted at the top, likely they were 'not opening' as designed. That Thermo-cure is some good stuff. I tried it based on success stories from Ford Barn.
 
solved. It was the junk in the system from years of 'trailer queen' life. With 160s the needle never passed 1/2 after 20 miles around town including on the road at 50ph, up and down hills and a long idle. Needle never moved. IR check found 160-165 most everywhere in cooling system. It took 4 flushes to clear the water. Went from solid brown to medium brown, to light brown to greenish brown to a bit of green. If I wasn't so stubborn I'd have done this a year ago. Thanks for the help, guys. Maybe I'll put a pair of 180s back in since that seems to be the preferred choice.
 
Dunk said:
solved. It was the junk in the system from years of 'trailer queen' life. With 160s the needle never passed 1/2 after 20 miles around town including on the road at 50ph, up and down hills and a long idle. Needle never moved. IR check found 160-165 most everywhere in cooling system. It took 4 flushes to clear the water. Went from solid brown to medium brown, to light brown to greenish brown to a bit of green. If I wasn't so stubborn I'd have done this a year ago. Thanks for the help, guys. Maybe I'll put a pair of 180s back in since that seems to be the preferred choice.
Click to expand...
Thanks for posting the follow-up. Its always good for us to learn the results, especially when it definitely solved a problem.

Yeah, now with cooling problem resolved, I would go with 180 stats.
 
DFW said:
Only driven my 40 flathead a couple times since I got it from my brother, he passed last Apr.
It gets hot, one water pump was leaking, I replaced both, carb was clogged, ran lean, rebuilt that now it's still running 210° at idle, both hoses are about the same temp, new radiator cap from Carpenter.....not sure what to do next....?
Click to expand...

When I got my 47 drove it for a summer no issues the next summer I flushed the rad hard to believe the crap that came out of engine. Might want to try that
 
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