Overheating on Autometer & normal on stock gage

[Psychdaddy]

Just got my 331 stroker running. It has approx. 120 miles on it and has an S-Trim installed. During the installation, I put a new aluminum radiator in and went back to the stock fan and clutch with stock fan shroud. Had to do this because the Mark VIII electric fan would not clear the 8-rib s/c belt.

Anyway, even if I drive it in the evening when the weather is cool, within 10 -15 min the Autometer gage will rise up to 230* while the stock temp gage remains in the "normal" zone, meaning it hardly rises above halfway. I have no coolant overflow coming from the canister nor is there overheating signs from the radiator pressure cap.

Any suggestions on which gage I should trust? Anyone else experienced this?

Chris

 

[Sicarius428]

My money would be on the autometer. Stock gauges are not to be trusted.
Kevin

 

[Mustang5L5]

Where is the sender located on the intake?

I'd trust Autometer over stock

 

[S&B]

Are you sure there is no air in the system?

 

[baskin]

I wouldn't trust either one, I've seen both off by quite a bit, and if it's as hot in the evening as it is during the day, then the thermostat is limiting the drop in temperature at night, given the fan clutch is good.

Check the ECT voltage to verify the temperature, you'll find the numbers here:

http://www.dccontrol.com/troubleshooting.htm

 

[superhuaman]

are you using the same sender for both gauges? and if not, where are both of them?

 

[HISSIN50]

I'm with Brian - you need more info.

In general (though not an excuse to let this go without troubleshooting) at op. temp, my stocker read ~35*F cooler than aftermarket mechanical gauge.

OT: Brian, I'll email you, but thank you very much for the schematic.

 

[Darkwriter77]

Try replacing the stock temp sending unit, if you haven't done so, already. Verify there are no kinks or weird bends in the line from the sending unit to the gauge of the Autometer unit. Are you running them both off of a T-connection at the intake? If so, it could be that the Autometer is running a true reading while the stock sending unit is far enough removed from the flow of coolant that it's not reading accurately - need to investigate things further for the cause of overheating, if that's the case.

FWIW, my Autometer temp gauge works about 90% of the time. For whatever reason, it occasionally gets a bug up its butt and will not give any reading at all from a cold start until I hit a bump or something just right that wakes it up, and then it's right up to 190* where it's supposed to be. I smoothed out a couple of somewhat sharp bends in the line to the gauge and haven't had any problems with it for quite awhile, now.

 

[HISSIN50]

A typical tee connection should never be used for a temp gauge(s) IMHO. The probe needs to be suscepted to the actual flow of coolant in real time. A tee can tend to allow coolant to pool in the alcove.

 

[superhuaman]

hmmm...i have a tee for my ect sensor (not the gauge sender).