2008 F350 6.4 Diesel EGR delete chipped.
 

Driving on a hot day and cruising around 70mph, the coolant temp gauge goes to hot and reduced power message is displayed. If I sit off road in park, with the motor running the gauge returns fairly quickly (you can see the needle fall) to normal and the trunk drives well again. The engine temperature does not appear hot nor has it puked out any coolant. I changed the thermostats with no change. The coolant level is correct and the fan is turning.

Can anyone help?

Thank you, Martyn

As a footnote to the above, I took the truck on a road test with a SnapOn scanner plugged in. When the fault occurred, the readings for the water temp were 197 and didn't move and the oil temp was 259 and steady. There were no codes stored, nor did it show a code with the fault.

Martyn

Your oil cooler is plugged up. At 259* on the oil, you're waaaaaaay out of spec. Anything about 20* above coolant temp is bad. You need to get that looked at asap.

and what are the codes that were pulled from the odbc port?

Thanks Speakerfritz and JoshCO17

There were no codes for some reason and I have taken the truck in to get the oil cooler sorted. I had previously changed the thermostats thinking that it was the coolant temp that was causing the issue. I didn't realize that the oil temp triggered the gauge on the dash.

Thanks Guys for your input and will keep you posted as to the results.

Martyn

I had a 6.0 that I just got rid of that did the same thing last summer. Cruising along pulling the camper and boom, all the sudden the dash starts beeping at me and the coolant temp gauge goes from normal to max in an instant. Later discovered that it was my oil cooler. Good luck with the fix. Report back when you get some good numbers.

Thanks Guys

I'll report back with the news.

Martyn