Normal Oil/Coolant Temps?

[AK800]

I think this the right section, so I'm trying to pick some brains. I've got an 08 Job 2, 350 and has been Spartan'd for about a year...love it! My issue is this: 3 weeks ago was pulling my 26' enclosed sled trailer and it was by far the coldest weekend of the season in southern Alaska (about -30). My truck has consistently ran right at 192-94 on coolant temp and 194.6 on oil temp---it's always been the same and has never fluctuated much. When I stopped to fuel up, truck was running at 190....no issues as I usually expect. As I pulled onto the highway again, in no less than 5 miles down the road coolant temp immediately hit 200 degrees...then 215, and soon was 220. Oil was about the same, so i pulled over and let it cool down. Limped it to the sled parking lot, rode the rest of the day and headed home. Drove it easy at 200 degrees coolant and 203 oil temp. Don't have a hydrometer to test the coolant freeze protection, so I can't asses what the protection is. Took it to Ford and had them flush and re-fill with -50 protection....they said there was no obvious problem. Now the truck coolant and oil temp get up to 200 consistently, hangs there for a few minutes, then it acts like the thermostat opens up and the coolant temp drops like a rock in about 5 seconds to 178-180. The oil temp drops, but not as fast. This happens and I'm not even pulling anything.

I know that these engines run on the hot side, and 200 degrees isn't all that much to be concerned about; what concerns me is that all of a sudden this started happening and sometimes my oil and coolant temps get way out of whack (around 20 degrees difference sometimes), but they eventually even out. Is this true that the thermostat doesn't even open until 200 degrees?

I know this is long, but any obvious ideas?

[bjornvick]

My first guess would be a sticking thermostat.

[AK800]

Im kinda thinking the same thing, just wondering if its worth the mess/hassle to open up the housing and replace it.

[quatackerb]

Your situation sounds like a thermostat starting to give up, but the oil coolers on these trucks are known to give up also. So if you start seeing a consistent large gap in temps between your oil and coolant then that's a sign your cooler is starting to clog.

[AK800]

Im thinking I need to look at my thermostats and possibly replace. Was thumbing through a few TSB's from Ford and dug this up:


TSB
09-23-1 6.4L DIESEL ENGINES - REPEAT RADIATOR LEAK - BUILT ON OR BEFORE 9/14/2009

Publication Date: November 9, 2009

FORD: 2008-2010 F-Super Duty


ISSUE:
Some 2008-2010 F-Super Duty vehicles built on or before 9/14/2009 and equipped with a 6.4L diesel engine may exhibit repeat radiator leaks due to malfunctioning (hyper-extended) high temperature thermostats.

ACTION:
Follow the Service Procedure steps to correct the condition.

SERVICE PROCEDURE

Verify the coolant leak is from the radiator, refer to pin point test (PPT) A found in the Workshop Manual (WSM), Section 303-03.
Verify the venturi tee is installed.
If installed, confirm it is installed correctly (note - orientation direction on part). Refer to applicable Field Service Action (FSA) for vehicle built on or before 5/15/2008.
If not installed, install per applicable FSA on vehicles built on or before 5/15/2008.
Prepare the vehicle for a test drive.
If the coolant leak at the radiator is large enough to cause an unsafe test drive or potential for engine/vehicle damage, proceed to Step 5.
Before driving the vehicle confirm the coolant level is at minimum level or above in the degas bottle. If required add 50/50 mix to coolant bottle.
Test Drive - use an Integrated Diagnostic System (IDS) or equivalent and monitor engine oil temperature (EOT) and engine coolant temperature (ECT) parameter identifiers (PIDS).
With EOT at 195 °F (91 °C) drive on the highway unloaded at 55-70 MPH (89-113 Km/h) constant speed to observe EOT and ECT temp.
Test results/next steps:
If EOT is less than 8 °F (4.4 °C) higher than ECT, and the coolant temp fluctuates roughly 5 °F (2.7 °C) - the thermostats are okay and do not need to be replaced. Replace just the radiator. Refer to WSM, Section 303-03 (Engine Cooling).
If EOT exceeds ECT by greater than 8 °F (4.4 °C) or if the ECT readings fluctuate 10 to 12 °F (5.55-6.66 °C) roughly every 30 seconds - replace both thermostats and radiator. Refer to WSM, Section 303-03 (Engine Cooling).
If vehicle is not drivable and the coolant leak is found to be from the radiator, remove and replace both thermostats and radiator. Refer to WSM, Section 303-03 for both radiator and thermostat removal procedure and approved cooling system draining, filling and bleeding procedures.

PART NUMBER PART NAME
8C3Z-8575-D Thermostat Assembly
8C3Z-8009-B Radiator Assembly


WARRANTY STATUS:
Eligible Under Provisions Of New Vehicle Limited Warranty Coverage
IMPORTANT: Warranty coverage limits/policies are not altered by a TSB. Warranty coverage limits are determined by the identified causal part.

OPERATION DESCRIPTION TIME
092301A 2008-2010 F-Super Duty 6.4L: Pressure Test Cooling System, Road Test, Monitor PIDS, Replace The Radiator (Do Not Use With Any Other Labor Operations) 3.0 Hrs.
092301B 2008-2010 F-Super Duty 6.4L: Pressure Test Cooling System, Road Test, Monitor PIDS, Replace The Radiator, And Thermostats (Do Not Use With Any Other Labor Operations) 3.8 Hrs.

DEALER CODING
BASIC PART NO. CONDITION CODE
8575 42