overheating?!?!?

[giddyup]

im having a werid issue with the truck...it only happens once in a while.while on the hwy cruising,no load,the temp gauge suddenly pegs hot.dash says reducing power.i look for a off ramp to stop,then the gauge goes back to normal and all is well.i pull off and open the hood,and truck seems to be fine.no excessive heat,fan is moving the air,overflow jug is at correct level ect.truck has had the new radiator,new overflow jug and all recals perfromed.it's a 08 job 1 truck with 145k on it.

what do you guys think i should be checking?

[greasltn]

If it's not puking, you may just have a bad temp sensor.

[mor4wd]

+1 on the bad sensor

[Big Angry Hillbilly]

Overheats that peg the temperature gauge SHOULD set codes...

They don't always though.

Could be a small air pocket, bad sensor (the only problem is there are a BUNCH of sensors that can flip the gauge up.)

Do you hear the fan ramp up as it's overheating? Er... as the temperature gauge climbs?

[giddyup]

Originally Posted by Big Angry Hillbilly

Overheats that peg the temperature gauge SHOULD set codes...

They don't always though.

Could be a small air pocket, bad sensor (the only problem is there are a BUNCH of sensors that can flip the gauge up.)

Do you hear the fan ramp up as it's overheating? Er... as the temperature gauge climbs?

nope fan running as normal....engine doesn t even feel hot.i thought the same thing on the air pocket,so when it did it again,i loosend the coolant cap and bled off the pressure.coolant did rise in the jug,just above the vent tube.it hasnt done it again tho....but i have noticed even after sitting for 3 hrs,if i turn on the key,the engine temp gauge is still in the middle.just like if it is warmed up,but the trans temp is cool.

[outlawtransport]

I have a 2008 F450 with the same problem. Ran the truck with a recorder from the dealer. Truck is now in service bay with a bad oil cooler and coolant in the oil. Don't wait on this. Same symptoms as you are describing.

[giddyup]

Update...took another 6 hour trip.3 hours into the trip,cleanibg exhaust filter comes on.within 10 miles temp gauge suddenly pegs hot,and display says reduced power.i pull over immeadiatly,and put it in park.gauge starts dropping,within a minute or two its back to normal,and i drive on.im starting to think the dpf is clogged.

[Big Angry Hillbilly]

Could be a bad EGT sensor. Have seen a few of them read somewhat high, and that's enough to put it into "Failure Effect Management Mode" because the sensor is telling the PCM something has got way too hot, when, in actuality the sensor is reading a couple hundred degrees too hot, but there's no way for the PCM to know that.

[outlawtransport]

unless the wrench light and check engine light come on it is not a clogged dpf. Have been through that also. You need to check your engine oil temp. It is not supposed to be more than 5 degrees above your coolant temp. Mine was 50 degrees above hence all the symptoms you are describing to a tee. Just my 2 cents. 2008 ford f450 with 252,000 miles

[dieselkane]

Originally Posted by outlawtransport

unless the wrench light and check engine light come on it is not a clogged dpf. Have been through that also. You need to check your engine oil temp. It is not supposed to be more than 5 degrees above your coolant temp. Mine was 50 degrees above hence all the symptoms you are describing to a tee. Just my 2 cents. 2008 ford f450 with 252,000 miles

Wow, what problems have you had in all those miles?