Inconsistent Overheating Issue

[paintballrocker]

So I was driving my truck to work today after getting home from a 3 week long military trip. Before I left I had no issue when driving the truck, even when going for 3+ hours playing in the mud and dirt roads. Anyways I drove to work and noticed my my hot air turned to cold air, Check and saw the temp gauge at 250ish. I let it cool down and later drove it back home. Well right before I pulled into the driveway it once again got back up to 250ish, losing the hot air in the process. Up until that point it was blowing hot air. When I parked it I let it idle and noticed that after 2-3 of idle it dropped back to the normal temp of 190, but still blew cold air. Turned her off and popped the hood, Upper Rad hose was hot, lower hose was warm, rad cap was hot, and overflow tank was drained almost all the way down. Checked the fan and it easily spins by hand and will spin for a sec or two after leaving my hand. Didnt check the dipstick to see if oil is milky or not.

Recently replaced both uper and lower rad hoses and t-stat.

Am I crazy to think it might be air in the system or the fan clutch and not a more serious issue? Im going to look into it more tomorrow after I wake up

[HenryJ]

Running Dex? If so change it out.

Did you get a new radiator cap? Stock one is bad. You need the one with the spring loaded vent to keep air out of the system. The Dex article has more details on that.
Keep that expansion tank full.

Did you squeeze the air out of the system and refill after the hose swap?

Check the radiator between the condenser. It gets plugged up in between.

Does the fan roar when the engine is hot? If it doesn't roar the clutch may be bad. Check the belt to make sure it is not slipping.

How is the fan shroud? Intact?

Got the bigger/thicker radiator? If not make darn sure the core is clean. The stock radiator is marginal IMO.

Sticky stat? When was it replaced last? Hows the waterpump? Leaks? Loose?

[paintballrocker]

t stat and rad cap was replaced montha go with both rad hoses, acdelco 190* fail safe tstat, rad cap with a spring loaded venting cap. went and check to day when i woke up. dip stick oil is good, just normal color. Over flow tank was just barely filled. rad cap was loose, and the rad was low, couldnt see fluid in the tank from the top, but squeezing the lower hose made fora gurgling sound from rad. so Im going to fill it up today after work, raise the front and run it to try to bleed it and then top it off with coolant. Hope fully that fixes it

also last night the fan didnt seem to be roaring as loud as normal, but i cant spin it more than 1/2-3/4 revolution by hand so idk if the fan clutch is good or not

[HenryJ]

Usually a bad fan will rotate freely when the oil has all leaked out. I usually see the leak at the front near the spring. Almost impossible to see installed.

If it is gobbling coolant, that is not good. Look for bubbles while full , warm and running. Maybe signs of a cracked head (unlikely) or blown head gasket (more likely). If those show neither, maybe suspect intake gasket leaks? Small internal leaks add condensation to the oil. Look at the inside of the oil cap or breather tube for condensation. Oil may be a little brown. It takes big amounts to turn the oil gray. Check with the engine warm.

Hopefully you just did not get it fully bled out after the hose swap and it will stay full now :fingers crossed:

[ApproachMedium]

My friends blazer that I just had repaired had the same issue when i first got it over a year ago. It needed a gallon of coolant added to the radiator to fix it, despite the thing having coolant in it. Once i added that it was fine. Until the reason for the leak got so bad it didnt make a difference. The leak was the intake manifold gasket. Careful inspection of things will probably be needed. Adding your new hoses could very well have added strength at one point bringing out the weakness at another.

[paintballrocker]

well almost a full container of 50/50 coolant and a good burp fixed her. I checked all around the intake with a mirror when i had the throttle body off one time and didnt see any signs of leaking. My oil fill cap does have a few drops of moister on it here recently, but even if i have a minor leak I am not concered as I ship the truck back to the states in a month and then its getting a vortec 350 swapped into it right away!

[ApproachMedium]

well almost a full container of 50/50 coolant and a good burp fixed her. I checked all around the intake with a mirror when i had the throttle body off one time and didnt see any signs of leaking. My oil fill cap does have a few drops of moister on it here recently, but even if i have a minor leak I am not concered as I ship the truck back to the states in a month and then its getting a vortec 350 swapped into it right away!

Before you do anything do a good read over of my thread. I believe Dave who did my install said hes going to put up something eventually about all the specifics of mounting the engine etc in the crew.