Cooling System Cracking Noise

[John K Nelson]

64 Plymouth, 502 wedge, street/strip. Engine rebuilt 2020: New heater core 2009.
December: New fully welded Cold Case aluminum radiator installed. Terrible cracking/popping noise after warm up and for ~1 min after shutting off. Upper hose, warm to hot. Heater valve open. Good heat from heater. Coolant violently boiling? Coolant: water w. Water Wetter for race track requirements. January: Changed t-stat from 195 to Motorad 206-180 and verified that the 195 has been installed correctly. SOS. Temp gauge never gets past 180, idling in a cold garage. February: Bought a Lisle burping kit. SOS. Bought a Stratos burping kit for heater hose. SOS. Pulled t-stat drilled 1/8" hole in flange. SOS. Considering therapy. Two bad t-stats? Unlikely. Run w/o t-stat?
Any ideas out there?

 

[davek]

new engine? if not did you have this problem before? If not new what have you changed before this happened. More info could help.

 

[Ranger16]

Normal expansion and contraction of the exhaust system?

 

[65-440]

Have you tested the radiator cap? If it's not holding enough pressure it will reduce the boiling point of the fluid in the system..

 

[69 Sleeper Bee]

A video or audio would help.

 

[pnora]

64 Plymouth, 502 wedge, street/strip. Engine rebuilt 2020: New heater core 2009.
December: New fully welded Cold Case aluminum radiator installed. Terrible cracking/popping noise after warm up and for ~1 min after shutting off. Upper hose, warm to hot. Heater valve open. Good heat from heater. Coolant violently boiling? Coolant: water w. Water Wetter for race track requirements. January: Changed t-stat from 195 to Motorad 206-180 and verified that the 195 has been installed correctly. SOS. Temp gauge never gets past 180, idling in a cold garage. February: Bought a Lisle burping kit. SOS. Bought a Stratos burping kit for heater hose. SOS. Pulled t-stat drilled 1/8" hole in flange. SOS. Considering therapy. Two bad t-stats? Unlikely. Run w/o t-stat?
Any ideas out there?

Coolant violently boiling but water temperature never gets past 180. That does not make sense. Cant have it both ways. I would verify what the temperature really is.What are you running for water pump, fan and shroud?

 

[Caterpillars]

That's a good idea - run without t-stat. If it still does it could be water pump...

 

[Dave6T4]

I had an impeller come loose from the pump shaft once. It took a while to track that one down.

 

[Ranger16]

Coolant violently boiling but water temperature never gets past 180. That does not make sense.

THAT sounds like "false boiling". Head gasket leaking?

 

[dadsbee]

You sure it's not just that aluminum rad expanding and contracting? Loosen it's retention bolts off a turn so it's free to "move" and see if the cracking sounds go away...

 

[bearman]

THAT sounds like "false boiling". Head gasket leaking?

pull plugs then crank engine over by hand see if any coolant comes out.

 

[840a]

Does the coolant system have an air pocket? If water pump is working correctly, t stat has been checked, radiator is flowing, pressure cap tested, then it is engine related or air in system. I would verify that fan is pulling air, test for hydrocarbons and most importantly verify that the cooling system is not locked due air preventing coolant movement.