04 6.0 2500 running hot

[Low Elco]

My neighbor has a 04 2500 with a 6.0 that's been running hot. He had a friend put a thermostat in it, and they airlocked it. The consensus was that it needed a waterpump. I did that last night, and added the better part of 2 gallons more antifreeze. It fired right up, heater got hot, all good, I put the cap on, let it sit idling for 10 min while I tidied up, it was at around 190. I took off and within a mile I was at 240. I shut it off and coasted back to the house, and it was back to 220. I fired it up and it was steady at 220. Any one got any ideas? Thanks, Chip.

[Jonboy]

When you did the water pump, did you fill it through the upper hose? If not, pull the upper hose and get some coolant in there.

[clinebarger]

Do Not trust gauges in '03-'06 trucks, They are fail prone, Usually they start buy reading wrong before they go completely bonkers.

Water Pumps are simple devices, They either Leak, Lock-up, Cavitate the housing, Or the Impellers rot off, Did you pop the cover off the back of the pump to verify the pump was actually bad? I assume it wasn't leaking or locked up.

I always make sure to catch all the antifreeze I drain from a vehicle, Then I put it all in leftover empty antifreeze jugs. This allow me to measure the Coolant that came out, So I know if the system is short on coolant (air-lock situation)

Thermostat, I have seen 1 or 2 Thermostats stick closed in my whole career, They almost 100% stick open.

Radiator, A Half to 3/4 clogged radiator core will cause overheating while driving.

[95 S_Trucker]

Check for debris between the radiator and A/C condenser.

[69gmcc10]

There could still be a air bubble in the system. Was there a vent hole in the T-stat? I always try to buy a T-stat that has the little vent hole in it or drill a small hole in the base plate of it to help minimize air getting trapped.

Get an IR temp gun and check the temp at the sensor in the radiator (top, bottom and middle) to see if the temp sensor is accurateish and if there is a blockage in rad. With enough tinkering you will get it figured out. good luck!

[Low Elco]

Temp sensor is on/correct. Did a new thermostat last night. Drilled a teensy hole in top of tstat. Filled at the jug with the top hose off till i got water out of both the rad and hose, Same deal, sits idle for 10 min at 190-200, then you hold a rev 2000-3000 for a minute-two, it jumps to 220, pauses, then heads for 240-250. Gun says 225 at the front of the head/therm housing. Hrmrrm.

Cline, I did the same. It was airlocked when they did the first stat, I added a gallon and a half. It's correct now.

Ps, thanks for the replies, guys. I'm headed for the lake. You TX boys try not to float away!

[Low Elco]

I believe it's the rad. I went over and checked tonight, 230 motor, 150 top hose, 73 ctr of rad. Gage is within 5 of gun.
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[88JRFAN]

Could the clutch fan be bad? Just a thought.

[Low Elco]

Idk, they're doing a rad while I'm out of town.
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[Boog]

What's the word Chip?

[68C15]

don't trust the gun. You're getting block and head temp. Go for reading at hose and put gun real close. Best way is to use scan tool. If yours doesn't offer data stream you can take a "picture" by creating a code. Then look at freeze frame data. Most code readers are capable of that