6.0 intermit over-heat under load

[keckals]

2003 6.0 EGR delete, 5 inch exhaust, mild tune 180,000

Will over heat sometimes under a good load, but then the next time its ok. Happens more at interstate speed (above 70), never gets warm anyother time.

Never had coolant in oil, tested coolant cap good till 15 psi. Never seen anything besides black smoke out the pipe. Cooling fan kicks in when its warm like it should.

Noticed oil temp is high (260F) before the coolant gets hot . Leaning toward oil cooler replacement.

Thoughts? Will try a new oil cooler and report back what I find

[southend]

260° eot? Your truck is going to self destruct if you keep driving it. You have a monitor? What is your coolant temp?

Sent from my phone that somebody didn't help me get.

[keckals]

[QUOTE=southend;3436446]260° eot? Your truck is going to self destruct if you keep driving it. You have a monitor? What is your coolant temp?

260 is the oil temp when the engine overheats (ECT 240), not all the time.

Im just trying to figure out if the oil is overheating and causing the coolant to over heat.

With the miles on the truck and the lack of a coolant filter untill recently, I'm still leaning towards the oil cooler.

[southend]

You should seriously stop driving the truck. Normal Ect is 190°. The oil temp should not exceed 15° greater spread, that would be your delta reading. Check both of yout temp sensors after it has cooled overnight. They should read close to each other within a degree or so. At the temps you posted, your truck should be defueling. If I was you, I would flush the cooling system, replace the thermostat and the water pump, then recheck deltas at op temp on flat ground at 65mph. How are you reading pid's?

Sent from my phone that somebody didn't help me get.

[twoicebergs]

You must be pulling one heck of a load to get those temps. Unless you're not telling us something, it sure looks like you have a blocked cooler! Unless you want a much larger repair bill, flushing and then replacing it should be your #1 priority. BTW, if your temps get any higher, your truck will go into limp mode. Oil temps that high for longer duration can severely shorten its useful life, leading to engine damage. Of course the high ECT has its own problems to deal with, including fluid breakdown and more sludge forming in the coolant system.

[excursioninaz]

find the flattest 5-10mile stretch you can, do 60mph and see what your deltas are. if they exceed more than 10* apart you really should change the oil cooler! i agree with everybody...STOP TOWING TILL YOU GET HER FIXED