overheat condition at 70 mph cruise

kevin phillips · November 7, 2009

Got a 08 6.4 that overheats at 70mph everytime after about a 20 mile trip.At 65mph it will not overheat or driving at lower speeds it will not have a issue.Anybody ran into this before? I've checked the radiator for restriction,coolant is full,no add ons on front end.Thanks for any ideas

Mikill · November 8, 2009

I would check the fan clutch after checking for any air restrictions in front.

Bruce Amacker · November 8, 2009

^^^ Ditto, and also I'd pull a vacuum on the cooling system with a RadKitPlus to make sure it's filled all of the way. Is there an Oasis history on this truck? Has the cooling system been apart lately?

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kevin phillips · November 8, 2009

It had a radiator installed about 6 month's ago.i will check fan with ids monday and make sure it has all speeds and seems to be pulling enough air,thanks guys

Brad Clayton · November 8, 2009

There are a few diferent perceptions of an overheating condition. Does the coolant gush out of the degas bottle? Does the coolant gage go into the red zone? Are the ect/eot pids climbing past 240 degrees?

When it comes to a Powerstroke I look soley at the eot pid to get an idea of how hot the engine is running and whether or not it is indeed overheating.

Just some thoughts.

LARRY BRUDZYNSKI · November 8, 2009

I would start with a infrared thermometer at the t-stat housing and see what it's reading. Fan clutch could do this but wouldn't it throw a code being a vistronic fan clutch? It had a radiator replaced 6 months ago....Could it have a pocket of air somewhere in the system? Was it filled with the proper coolant and mix? T-stat's have been a issue. Have you checked them? Cavitation? Pump?

Aaron · November 8, 2009

I have seen the visctonic fan clutches not work properly and not set codes

kevin phillips · November 9, 2009

Guage shows overheat,ids on ect shows overheat,fan does run on high speed by sound of fan during overheat.not sure on refill procedure radiator installed at another dealer but wouldn't air have worked it's way out of the system by now ? i have not removed thermostats or water pump to inspect.It looks like more airflow across the radiator at 70mph would make it hard to overheat and why will it not do it below that speed just puzzles me.thanks for the advice guys will update when i check some more tommorow.

cbriggs · November 9, 2009

Posible cavitation related to engine speed? Try driving in a lower gear at slower speed, but same rpm as at 70mph in top gear. May shed light on wether its air flow or coolant flow problems?

kevin phillips · November 11, 2009

Cavitation in front cover behind water pump.Got a cover on order,thanks for the help guys.i'll update when i get it put back together but my guess is it will fix it.thanks again