erratic coolant temp readings

[94slowbra]

i am monitoring vitals with an edge cts. as of lately my coolant temp has been acting a little funny. it will warm up like normal and oil temp will stay about 5-10 degrees behind ect up until 192. the the oil will steadily rise about 5-6 degrees above ect. then randomly ill look at the gauge and the ect will be at 174. it may sit like that for a min and then jump back up to normal temp, within 5-8 degrees of eot. eot will never fall like the ect. i have a new ford thermostat less than 6 months old, no coolant leaks, new oil cooler, coolant filter and elc coolant. my guess is a sensor since the eot stays pretty steady. never had a wrench light either and sometimes its stay 30 degrees different for a few minutes. what sensor does the gauge read? easy to change? any other thoughts as to what it could be? thanks

[Lilpooh]

I had a similar temp cycling once, but mine was the opposite. ECT would climb, then drop to normal and cycled like that about every minute. My issue was the impeller spun off the water pump shaft.

http://www.thedieselgarage.com/forum...ad.php?t=98330

This was just my experience. Good luck with your trouble shooting.

[94slowbra]

god i hope not. like i said before not rising just dropping.

[WarChild]

Sounds like your thermostat is sticking open. try changing it out. its cheep and simple. if that doesnt work then I would start looking at the water pump. But it sound just like a sticking thermo to me. Good luck!

[94slowbra]

If it was the t-stat would the oil temps drop too? The ect affects the eot. Maybe it doesnt have enough time to affect it

[WarChild]

Not really at those temps.

[Treyloco]

Had the same problem a few weaks ago and it was the temp sensor. pull the codes and see if it is a low output problem on the temp sensor. Have fun changing it if you need help you know where i live. I think you need a 21mm med. depth socket.