Recently purchased a 5.3 LM7 swapped C10 which showed questionably low temperatures. Upon returning home I see the radiator leaks and this was swapped over with a new aluminum 3-row from a different LS swap.

Once swapped coolant then rose to 180, which is about 3/4 on the gauge and significantly higher than the 145-ish it showed on the 1 hour drive home. This led me to worry it had an air pocket.

I then drilled a small hole in thermostat to see if this would help the air pockets, as multiple refills/burps led to the same result. Immediately thereafter the coolant would not rise above 135. Acted like an open thermostat, so i bought a new thermostat and still cannot get this coolant above 135.

Engine feels hot, radiator feels cool, upper hose hot, lower hose cool, temp gauge reads 135 after 20-30 mins of idling and still, thermostat doesnt open.

Would it make any sense that my engine does not get above 135 at idle on a 90 degree day? Bubbles will come and then stop, but i do not see the engine drink coolant nor does it flow in radiator?

I would suspect a thermostat stuck closed, but its the 2nd new one. I would suspect engine temp is remaining at 135, but gauge is iffy and coolant is not flowing in radiator.

Any ideas? My mechanical gauge wont thread fit and i do not want to let this run longer than 30 mins without coolant flow if it is actually getting hot.

 

Electric fan? Pushing or pulling? Does it have a fan shroud? Whats the operating temp
of the thermostat? Electric or mechanical water pump?

 

Stock fan setup, big white fan and shroud fits very well. Thermostat engages at 185, the other at 160. Stock water pump

 

I went through something similar with my Challenger I had to buy 3 thermostats before I got one that worked and I ended up testing it in hot water to see if it would actuate before going through the trouble of replacing it.

 

EVERYTHING today is TOTALLY screwed up. Quality, availability, you name it. Today it's customer DISservice, because customer service is no longer available at 90%, or more, of businesses. I don't want to even get started, so........

 

After that whole COVID fiasco everything’s turned to ****.