Right. If you've been following the adventures of MagPie, I keep struggling with overheating problems. System has been bled a few times, I havent heard any waterfall noise in the cabin and have had fairly consistent hot heat from the vents. I have a new WP / Rad / Fan / Clutch on the way but I wanted to get some base line numbers for temps in my cooling system. Truck was idling @ 190.5 parked on a slight grade, engine pointing uphill.

Equipment:

New 180stat (grey from Lucky8)
New Hoses everywhere (AB kit)
WP was replaced within the last 5k miles (not sure if the impeller is plastic or metal)
Radiator is original (as far as i know)

I shot the temps from the back side of Rad (the engine compartment side)

Upper left corner of Rad: 190
Upper right corner of Rad: 122
Lower left corner of Rad: 155
Lower right corner of Rad: 100

Upper cooling hose from bleeder T to Rad: 171 @ Rad and 140 @ T
T to block: 167
T-Stat to T: 178
Rad to T-stat: 114
WP to T-stat: 155

Expansion tank: 175
Heater core hoses were both 133

I guess what is surprising to me (and probably i don't fully understand how the cooling system works) is that the coolant coming out of the radiator is 114 to the T-stat and then from the T-stat back up to the bleeder screw it gains almost 60 degrees. Granted it is getting mixed with the coolant coming from the WP so it makes sense but it seems like a lot of increase within a short distance of hose. ALSO, from the bleeder screw to the radiator, the hose gains 31 degrees?

Thoughts?

 

What temp are you seeing when it over heats?

190.5 is not too shabby parked at idle

 

 

Couple of questions/ follow ups:

1. Did you flush the system?
2. Is the 260 under load or just it just spike at any point and time?
3. Can you turn the heater on full blast and recheck the heater core lines?
4. Is upper left drivers side or passengers side?

 

Sounds like an air pocket or faulty temp sensor.

 

1. Ran distilled water for a few days, probably drained and filled twice before adding the green stuff.
2. Drove for 20ish miles on fwy (everything was fine) and less than 2 miles up a fairly steep road it overheated within a few mins.
3. Yep, forgot to do that.
4. Upper left is drivers side

 

Isn't it fairly rare that a temp sensor would be poo?

 

Sounds like an air pocket is still in the system, did any coolant bubble out or was it just a temp spike?

 

 

I’ve had the lower unit temp sensor on an SAI D2/P38 go nuts. Never a top unit on a D2, but at 260F you’d have a dead engine so I think it’s reporting the wrong temps to the ECU/Ultragauge.