Could it be the temperature sensor? It is brand new.

 

absolutely could be.. have the old one?

without a stat, your cooling system will be wide open, which means the fluid is traveling the full circuit, and will take a long time to heat.. unless you have a blockage somewhere.. that is the reason I said to take the stat out.. in ten miles, if your system isn't blocked, and your getting a good reading, you won't get to operating temperature (closed loop), much less overheat.

 

I put the old stat back in because I knew it worked when I took it out. If the stat isn't working, then why would the temp stop at 230? Wouldn't it overheat?

 

Alright, just tested the brand new stat I put in and it worked beautifully -- opening and closing. So, it is something else. Yes, I have the old temp. sensor.

 

Just to be sure, the temp. sensor is to the right of the stat housing?

 

the stat retards the flow before the temperature allows it to open, which allows more coolant flow past it.. w/o a stat, the engine is flowing fluid at the same rate it would if the stat was wide open (due to temperature).. if the engine starts flowing the fluid at it's full capacity, which it would if there were no stat in it, the temperature would remain very low, because the radiator is extracting any heat it has possibly generated.

at worst, you will get a 1281 error (engine too cold for too long).. you will make it to the shop no problem though.

if your engine quickly gets hot w/o a stat, you've got other problems my friend.

 

what year is your truck?

some have two sensors, others have one.. I think it went to one in 98 but I won't swear to that. there are two castings on the keg- one to the right and one to the left.. it doesn't matter as long as it's in there.. if you have two, i'd rec you remove the blank in the unused one and put your temp sensor in that one- then you can fire the truck, let it warm STOP IT, swap the wiring plug to the other sensor, and fire the truck to see if you get a different reading.

 

[QUOTE=drewactual;2443787]the stat retards the flow before the temperature allows it to open, which allows more coolant flow past it.. w/o a stat, the engine is flowing fluid at the same rate it would if the stat was wide open (due to temperature).. if the engine starts flowing the fluid at it's full capacity, which it would if there were no stat in it, the temperature would remain very low, because the radiator is extracting any heat it has possibly generated.

at worst, you will get a 1281 error (engine too cold for too long).. you will make it to the shop no problem though.

if your engine quickly gets hot w/o a stat, you've got other problems my friend.[/QUOTE

Here is what I will do: I will take the stat out and see what happens. I did cut that little tab off the housing. Hopefully, that will make it a little easier to get out. I may also put the old temp. sensor back in and see what happens. Wish me luck.

 

Did you lay the fan down horizontally (i.e., laid the water pump or the fan flat on the ground)? If so, and it was left that way for any length of time, the viscous fluid in there could have contaminated the bearings, which makes the fan all but useless.

It will still spin freely, and make a sound like it is kicking on (takes a good ear to hear this), but the added resistance of the VF in the bearing lubricant makes it spin slower, and the absence of the VF at the edges of the disc (which is where its supposed to be when it's "on") will not let it spin faster through centrifugal induction (which is the whole idea behind a fan clutch).

EDIT: to make this easier to understand, this is how a fan clutch works: The fan is spun by the water pump pulley, but because it rides on bearings, it spins at only a fraction of engine speed. In steps the fan clutch. The little coil on the front is a temperature activated switch. Once at temp, the coil expands, and opens a gate inside the clutch that frees a passage for the VF to go to the outer edges of the disc where the clutch plates reside. The presence of this fluid makes the clutch plates more resistant to slipping, and also adds to the pull of centrifugal force (could explain this too, but i wont for the sake of length...google it up if curious), which makes the fan spin faster.

 

Yes, it was laying down flat for a week. I'm going to try without the stat first and see what happens. I'm doing that now.