Did you flush with the thermostat in?

 

Sorry I did not reply sooner.I had to go out of state for a week. I removed the thermostat when I flushed the system. I jacked the front end of the truck and used a no spill funnel to remove all the air/bubbles. I am wondering if the one sender that is wired to the ECM might of gone bad with all that oil in the coolant.I think I'll go ahead and replace that sender tomorrow and see if that is the problem.Running out of idea's. I am still open to suggestions,opinions,or advise on this problem.
Thank you very much for all your help.

 

The sender that supplies temp to the PCM is the one in the thermostat housing - it is not wired for the gauge. The sender for the gauge is in the cylinder head. If I’m not mistaken, some engines had a sender in both heads, so since you already replaced the one on the left, check to see if there’s one on the right.

Keep in mind the gauge depends on the circuit resistance and voltage being correct. As the temp of the sender increases, resistance decreases and the gauge displays the corresponding temperature. For the gauge to read a low temperature indicates the circuit resistance is high, so either the sending unit is faulty, there’s a loose/corroded connection or a partial break in the wire that feeds the gauge.

The circuit is powered by the gauges fuse with the key on - with the sending unit unplugged there should be battery voltage at the connector as well as at the gauge cluster connector, pin R, a dark green wire. More than 0.5 volts less than battery voltage at either of these 2 points indicates a problem with the circuit.

 

Thank you Gumby22 for your expertise with this problem.I will get my meter out and do some testing on the wiring and senders. Hopefully I can find the problem.I appreciate your great help. Will post again later with my findings.

 

Well,I finally got this problem fixed. Eventhough I had replaced the CTS about 1 year ago,after replacing it again,everything is back to normal.The gauge will be reading between 195 and 200 degree after the truck runs about 15 minutes. I guess when the water and oil mixed together,something must of happened to the sender that caused it not to read normal temperature. All is good now. I talked to one of the technicians at Edelbrock explaining to him how one of the pipe plugs that they put in the lower side of the intake corroded and caused water to go into the oil pan. Of course he would say that the truck had been driven with normal water in the system instead of the 50/50 antifreeze.I told him I was the origional owner of the truck and that I always ran the truck with antifreeze coolant in it. I had bought the intake about 9 years ago.
He said the intake only had a 1 year warranty and that it was well passed the warranty. Anyway,the truck is back to normal now. I want to start sanding the truck to get it ready for painting but its too hot out here ( I am in arizona) so I will wait til around september before I start the new project.As usual, thanks to all for your comments and opinions and suggestions with this problem.