2008 f 350 towing a 5th wheel after 90 mile run suddely goes to overheat reduce power,i reduce speed to 45mph goes back to normal. fan , thermostat,radiator , star Leaaking, all replace, i am getting a back presure?????

 

Ihave a scangauge2 monitor the engine, water temp 195/197 oil temp 230 at 1500 rpm increse rpm to 2000 oil goes up to250, and if i increse more oil will overheat and go to reduce power, ???? is the oil cooler?? and what cause cooler faiure???

( For $169)scangauge2 investement is a good monitor for your truck

 

Driving the truck down the road you should not see more then a 10 degree difference. Under a load this can change as the pistons are oil cooled and once the oil is heat soaked and can take a little time for the coolant to cool the oil down as the coolant temp will drop faster then the oil temp.

250 is way to high, at that point i would actually change the oil. From what you are describing it sounds like an oil cooler issue and should be checked out buy a reputable shop that works on powerstrokes and has the proper scan tools or the dealer. If you let this issue go or continue to push the truck at those temps you could turn a small issue into an engine failure.

Silicate based coolant will degrade and drop silicates which can ultimately wind up in the oil cooler plugging up the small passages resulting in insufficient cooling.

To avoid this Maintaining coolant at proper intervals is very important on the 6.0l and 6.4l. Nitrate levels should be checked on a regular basis to avoid cavitation corrosion issues. I also recommend the installation of a coolant by-pass filter which can also aid in keeping casting sand and dropped silicates out of the coolant.

Here is a good article to read and understand this better why the fail. It is for a 6.0 but the 6.4 cooler is very similar.

6.0L Power Stroke Oil Coolers - DTS Articles - Articles - Articles - DTS

 

Hi yiannis, welcome to FTE!

I've split your thread into its own in the 6.4L forum. You posted in another thread which may or may not be discussing the same issue your truck is experiencing.