923a2 temps at different spots

[TexAndy]

I've been trying to get my cooling fan to come on with no luck.

Replaced the shutterstat with a 190 (originally had a 200). The fan clutch does work(tested with air, directly). The shuterstat IN line is getting air. Coolant reservoir is filled to bottom of fill tube

BUT... the water pipe the shutterstat is threaded into is only getting up to about 110, measured with non contact thermometer.

Gauge in dash read 200.

sides of engine block was 155. Water pipe at shutterstat 110. lower half/side of coolant reservoir was bout 145. Passenger side of radiator (solid metal portion) about 135. Driver side of radiator (solid metal portion) about 100. Center of radiator (inboard side) about 95.

Exhaust manifold about 260 or 270.

So, I'm wondering I have a bad water pump, bad temp gauge, or both?

What concerns me is that the water pipe the shuttersttat is threaded into is so much cooler than the engine block. Same for the radiator. Clearly, the shutterstat is not opening because it isn't getting warm enough. But is that because coolant isn't being properly circulated or because I'm not letting the engine get hot enough overall?

I'm just not sure what the temps at various spots are supposed to look like in normal, everything functional condition.

Any help would be most appreciated.

 

[TexAndy]

Success. I didn't give it enough time the previous attempt.

Ran it again and was sure to measure at that flange right above the thermostat/thermostat housing. When that got to about 170 is when the driver's side radiator and coolant inlet pipe temps started climbing. Which makes sense, according to the TM's, I think. If the internal bypass thermostat opens at 180, it would make sense that the inlet pipe/shutterstat wouldn't see much temp increase until then.

I had to set the hand throttle about 1600 rpm to get it up to temp, but when that inlet pipe/shutterstat reached about 196, it kicked on the fan clutch. Wasn't gradual, either. It was pretty sudden. The fan kinda danced a few degrees a minute before that, but that was about the only warning I had.

 

[TexAndy]

I did note also that my transmission oil temp got up to about 275 (according to the gauge) and the air compressor got to about 225 (measured by non contact thermometer). Not sure about those. One thing at a time.

 

[WillWagner]

Those temps are fine. When the block loop gets hot enough for the stat to start opening, the cool coolant from the radiator loop cools the sender enough to shut the fan off, close the stat and re direct the flow back through the block loop. It is called stat modulation. Only after running it long enough, with a load, will the stat completely open and block off the bypass loop. . The WP is a simple design and the block it volute. If a pump goes away, like the impeller falls off or rusts off, it will over heat right now, like 220+, in short order. That is when these early engines like to crack the block between the liners.

 

[TexAndy]

Those temps are fine. When the block loop gets hot enough for the stat to start opening, the cool coolant from the radiator loop cools the sender enough to shut the fan off, close the stat and re direct the flow back through the block loop. It is called stat modulation. Only after running it long enough, with a load, will the stat completely open and block off the bypass loop. . The WP is a simple design and the block it volute. If a pump goes away, like the impeller falls off or rusts off, it will over heat right now, like 220+, in short order. That is when these early engines like to crack the block between the liners.

Yeah, the fan didn't run long. Maybe 15 seconds. But it cooled that pipe down from 196 to about 182.

 

[74M35A2]

Trans oil temp should be approx. same as engine coolant temp, unless you are working the trans pretty hard. Or unless your gauge or sender is wrong.

 

[TexAndy]

Trans oil temp should be approx. same as engine coolant temp, unless you are working the trans pretty hard. Or unless your gauge or sender is wrong.

I don't trust those transmission oil temps. This was just with the vehicle stationary, in neutral.

 

[CARMAN]

I used to freak out with same issue and thought truck was going to overheat since temps were all over the place. Fan has only kicked on a couple time since I have owned the truck and WOW...you knew it. Was stuck on the interstate on a 100 deg. day. Truck did not like that so I got off on a side road to keep the truck moving but every few minutes the fan came on and sounded like a jet next to me.