water pump, tstat or radiator?

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steveh

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69 dart 318 (15yr old rebuild) overheated...towed it home...trying to diagnose the problem...right answer is replace all three to ensure no more problems

doing that but also want to learn...so heres what happened

overheated at hiway speed, no chatter from pump

refilled with water...ran it at idle...top hose never got hot...shroud side radiator fins all wet...cant tell if rad is leaking or if its just left over from the first time it overheated.

like I said, I'm gonna replace all three for extra insurance...but want to learn proper troubleshooting...
 
Well id pretty much eliminate the water pump and focus on the rad and thermostat first. Easiest way to test the radiator is to dry it of real good (use of compressed air and a blow gun will make this task easy) then fill her up and start her up. Let engine idle if there is a leak in the radiator you should be able to see it trickle out unless its one of those super hard to find leaks. But if you have the same setup youve been runnin for 15 years and all the sudden its overheating. Id put my money on the thermostat as being the issue. Too cheap to not replace anyway jmo.
Hard to exactly diagnos the thermostat, but usually thats the main cause of a overheating problem
Also do you have a electric fan or mechanical fan?
 
71DodgeDemon340 said:
Well id pretty much eliminate the water pump and focus on the rad and thermostat first. Easiest way to test the radiator is to dry it of real good (use of compressed air and a blow gun will make this task easy) then fill her up and start her up. Let engine idle if there is a leak in the radiator you should be able to see it trickle out unless its one of those super hard to find leaks. But if you have the same setup youve been runnin for 15 years and all the sudden its overheating. Id put my money on the thermostat as being the issue. Too cheap to not replace anyway jmo.Hard to exactly diagnos the thermostat, but usually thats the main cause of a overheating problemAlso do you have a electric fan or mechanical fan?
Click to expand...

mechanical fan
 
If the top hose never gets hot and the water does not evaporate from the rad, then it is most likely the t-stat, with the rad and lower rad hoses collapsing as distant 2nd's. Top hose should get warm when the t'stat opens, even if the rad is flowing slowly.

Pull out t'stat, check in top of tank to see if there is coolant flow. If so, then pump is likley fine. If not, then check further into rad, lower hose or pump.

I'd pull it all out to check anyway. 15 years is a really long time on the cooling system parts.
 
You could always take the thermostat out and put it in a pan of water. Put a thermometer in and begin to boil the water. At 160 or 190 it will open up. That is if it is working.
 
X2^ forgot about that. But if im going to take it out its gonna get a new one reguardless lol
 
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