I installed a 34" radiator about 3 weeks ago. Shortly after tuning with the new 05 fans she got hot (from going 115 for the first time in the truck). Well right after I noticed the temp was high, so I pulled over and we saw the coolant tank burp and gargle, It was just an air bubble, I drove slow home after that.
Well now if the outside temp is 80 or above and I go 75 mph or faster the coolant temp goes up to 240 or so I will get the HOT COOLANT warning
I wasn't sure if it was the grille, so I took it off and it didn't mater
I tried seeing if there was more of an air bubble in the system but I'm about 90% sure that its all gone. I had the fans on High when this was happening to see it it would cool it any, but it didn't matter. And it only happend when its hot out and going 75mph or faster on cruise control (not abusing it either).
if its a little cooler it would happen when only going faster like, 50 outside I could go 85mph.

The only things that I can think of are:
1) Thermostat, doubt it cause it would happen all the time then, and only 32K on it.
2) Radiator, It was used but seller said it was flow checked and was good.
3) Possible air in system but doubt it.
4) I Don't Know

I'm at a loss.....

Thanks in advance for all your help

 

From the symptoms you describe, it sounds like the radiator may be plugged.

 

Is there an easy fix?

 

If a plugged radiator is the problem, the only way I know to cure it is to have a radiator shop boil and rod it. Does the truck overheat around town, or is it only on the highway?

 

Only on highway and not beating on it, it will happen in cruise control. If I do abuse it around town its fine.

 

Do you have a tranny cooler mounted to the radiator? I had problems with it restricting airflow through my radiator, had to take off and mount somewhere else.

 

Stock one only

 

are the fans going the right direction? i ran into this problem when i was doing the 80e swap. mine ended up being the top fitting in the rad. it is the one that goes from the rad to the fill tank. 1/2 inch hose. the fitting in the rad has a tiny hole in it. the rad shop drilled it out all the way. after that no more problems. i also keep that hose off while refilling the cooling system. then i usually started up the truck and let it fully warm up with out the cap on. good luck. maybe the therm is sticking at one point. it is not lewtting coolant flow fast enough at higher speeds.

 

I used that hose to top the system off, and coolant flowed through that very well.
I'm not too sure on the thermostat because its fairly new (33,000mi) and it would in theroy, happen all the time.

I'm still not sure???

 

I like your front grill but it looks like it cuts out 50% of available flow?