New coolant issue

[Logan R]

Well the system says it take 18 quarts with ac, which is what I have so I know its now low after I drained the block. So I would bet air in the system would be the culprit, as the system worked perfectly so it would make sense to me it has a lack of coolant.

 

[Logan R]

And yea the fan works to my best guess since it spins when I feel it should

 

[Schurkey]

Well the system says it take 18 quarts with ac, which is what I have so I know its now low after I drained the block. So I would bet air in the system would be the culprit, as the system worked perfectly so it would make sense to me it has a lack of coolant.

18 quarts capacity, that'd be 9 quarts for a 50/50 mix.

9 quarts is 2.25 gallons. 3 gallons of antifreeze is not going to hurt anything. I prefer a stronger mix than 50/50, but this area sees genuinely cold weather. Most folks don't need more than 50/50. Anything over ~70/30 is counterproductive. I've run 70/30 or close to that, on multiple vehicles for years, there's nothing harmful there...just that most folks don't need that much antifreeze.

And yea the fan works to my best guess since it spins when I feel it should

Do you ever hear it engage?

From cold, you start the engine and the fan spins and seems to blow a lot of air. The engine warms up, and it blows a lot of air. The engine gets warm enough to engage the fan clutch, and there's a sudden, dramatic increase in both noise and airflow. Dorothy and Toto fly past the car. The airflow is TREMENDOUS.

If you don't ever hear the sudden, dramatic increase in airflow when the engine gets truly hot, you have no confirmation that the fan clutch works.

It generally takes blocking the left and right thirds of the radiator core with paper or cardboard, leaving the center third open to airflow, to get the engine hot enough to test the clutch.

There are vehicles that trap air in the cooling system, the manufacturer has to provide bleeder-screw(s) to allow the air to be removed. GMT400s are not like that. All the air in the engine water jackets is GONE the moment the thermostat opens. All the air in the heater system is GONE within a few moments after you start the engine (you might have to turn the heater on, if you have "rear heat" on an SUV.) Both areas--the engine and the heater system--blow the air into the radiator where it's seen as a "low coolant level". There's no place in the GMT400 gasoline engine cooling system that traps air. I don't know about diesels.

If a GMT400 has a problem with not being able to "bleed all the air out", it's not air, it's combustion gasses that enter the cooling system via a popped head gasket, or cracked castings.

 

[PlayingWithTBI]

What should I do about it getting hot? Would driving it help? It was just idling. I just don’t want it to get too hot.

When I 1st installed my 383 Vortec style block with TBI style heads, I put in a 180° T-Stat which I drilled a 1/8" hole in. The temp in the head, where the sensor goes, got up to 250° before the T-Stat opened. The sensor, feeding the ECM, by the T-Stat housing showed ~180°. Then the head temp came down quickly to ~10° higher than the ECM one. I pulled the T-Stat and drilled 2 more 5/32" holes in it. Now it doesn't peak that high. I don't have any issues with it now, the head sensor reads a consistent 10° higher than the ECM sensor.

When you start it up, and you see your temp getting up to ~180° try revving it up some to get more fluid circulating through the system. See if that helps keep it down until the T-Stat opens. YMMV

 

[Logan R]

Ok sounds good, I’ll try that. I also put in 2 gallons of concentrate then 1 gallon of 50/50 and plan to top it of with 50/50 for the rest of the 2.5 gallons it needs

 

[udidwht]

You may also have dirty radiator tube fins impeding airs ability to flow thru the radiator and shed heat. It will look like this if dirty... https://www.gmt400.com/attachments/20220822_211040-1-jpg.320564/

After cleaning: https://www.gmt400.com/attachments/20220823_192819-1-jpg.320615/

Use a 'Radiator genie' from behind the radiator to clean it out. You'd be amazed at how much cooler it will run afterwards. I'm certain there were many who were told they needed a new radiator. Then paid big bucks to replace it. When in reality it just required some TLC.

 

[Caman96]

Use a 'Radiator genie' from behind the radiator to clean it out. You'd be amazed at how much cooler it will run afterwards.

This is so common in the Atv world every spring in the mud. Guys start posting “why is system overheating”? Radiator Genie and a rinse often resolves issue.

 

[Logan R]

Well thanks to all for the help, I replaced the fan clutch and can now hear it kick on and off. It now stays below 200-210 degrees and it should be about 180, so that’s awesome. And the radiator is dusty if that. I do have a question. What is the best aftermarket radiator and electric fan combo? Just curious as the old stuff seems small and dinky.

 

[alpinecrick]

You may also have dirty radiator tube fins impeding airs ability to flow thru the radiator and shed heat. It will look like this if dirty... https://www.gmt400.com/attachments/20220822_211040-1-jpg.320564/

After cleaning: https://www.gmt400.com/attachments/20220823_192819-1-jpg.320615/

Use a 'Radiator genie' from behind the radiator to clean it out. You'd be amazed at how much cooler it will run afterwards. I'm certain there were many who were told they needed a new radiator. Then paid big bucks to replace it. When in reality it just required some TLC.

This^^^

Spray the radiator and condensor with foaming coil cleaner, and hose from behind with a Radiator Genie type nozzle. In my part of the country the fins can become clogged with tiny pebbles, digging those out require a bit of patience.

 

[Scooterwrench]

Too much anti freeze is a bad thing. They shouldn't label anti freeze as a coolant,it's not. Ethylene and propylene glycol is a water treatment designed to raise the boiling point and lower the freezing point of water,it's the water that does the cooling. If you live in a cold climate you can get away with running stronger concentrations of anti freeze but in most of the world 50/50 is the max. The closer to the equator,the less anti freeze you will want to run. Running less than 20% anti freeze is not good either because you still need water pump seal lube and protection against rust formation that naturally occurs in iron engines.

Circle track cars run distilled water with no anti freeze to maximize cooling with high pressure systems to prevent boiling.