250* oil temps.
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5th Wheeling
Joined: Jun 2025
Posts: 28
Likes: 8
Did you ever check the oil cooler bypass valve? I've not taken mine apart, but I believe it's as simple as remove (2) screws at the bottom of the oil filter housing and remove/check the valve. Make sure the spring isn't broken and the valve itself is intact, etc.
If you look in the 6.0 bible they have a picture showing what is what in the oil filter housing. Sorry, my work firewall won't let me post or see images or I'd show it to you.
If you look in the 6.0 bible they have a picture showing what is what in the oil filter housing. Sorry, my work firewall won't let me post or see images or I'd show it to you.
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5th Wheeling
Joined: Jun 2025
Posts: 28
Likes: 8
Sounds like the original seller lied, mis-represented, and withheld information. Sad there are people like that, but it is probably very common.
If you do anything with the oil cooler, you also need to find out about the EGR cooler. In other words, determine if it is it still active or not. As stated earlier, a really clean EGR valve isn't necessarily a good thing.
If you do anything with the oil cooler, you also need to find out about the EGR cooler. In other words, determine if it is it still active or not. As stated earlier, a really clean EGR valve isn't necessarily a good thing.
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5th Wheeling
Joined: Jun 2025
Posts: 28
Likes: 8
Sorry for your troubles for sure!
Your situation is why I put the thread together on "How to buy a used 6.0L". A buyer simply MUST get educated, and then assess a half dozen (or so) critical parameters before even making an offer on a used 6.0L. Assessing the coolant system and the health of the oil cooler is one of the very first things that must be done. This is because the cooling system is where most owners make the most mistakes, and mistakes in engine cooling almost always becomes very costly to rectify. Another one is fuel pressure and injector health (injectors are expensive). There are more, but to complete the "big three", evaluating fluid filtration (oil, fuel, air) is critical. I wouldn't buy a used 6.0L that had an aftermarket oil filter on it!
Unfortunately, finding these forums (and NOT Facebook) seems to mostly occur after the vehicle purchase has been made. Even when/if people find the forum before buying the vehicle, most of them simply can not be convinced of the fact that a scan tool and a test drive (maybe even more than one test drive) is a REQUIREMENT (around $100 investment) before making an offer/purchase.
It is hard for me to imagine that in this day-and-age, the forums aren't being used at (near) 100% to learn of a specific vehicles flaws and weak points before buying.
Your situation is why I put the thread together on "How to buy a used 6.0L". A buyer simply MUST get educated, and then assess a half dozen (or so) critical parameters before even making an offer on a used 6.0L. Assessing the coolant system and the health of the oil cooler is one of the very first things that must be done. This is because the cooling system is where most owners make the most mistakes, and mistakes in engine cooling almost always becomes very costly to rectify. Another one is fuel pressure and injector health (injectors are expensive). There are more, but to complete the "big three", evaluating fluid filtration (oil, fuel, air) is critical. I wouldn't buy a used 6.0L that had an aftermarket oil filter on it!
Unfortunately, finding these forums (and NOT Facebook) seems to mostly occur after the vehicle purchase has been made. Even when/if people find the forum before buying the vehicle, most of them simply can not be convinced of the fact that a scan tool and a test drive (maybe even more than one test drive) is a REQUIREMENT (around $100 investment) before making an offer/purchase.
It is hard for me to imagine that in this day-and-age, the forums aren't being used at (near) 100% to learn of a specific vehicles flaws and weak points before buying.
Fleet Mechanic
Joined: Jul 2013
Posts: 1,402
Likes: 114
From: Tuscaloosa, AL
I feel for you. I trust no one with flushing the system. I flushed mine for a full day and I can drink out of my cooling system. It is practically sterile. BUT, I've replaced two oil coolers about 25k miles apart. I finally went with the BPD oil cooler relocation kit. Now an oil cooler replacement is a 45 minute job. I didn't go with the air to oil cooler because it was more work and the oil could run too cool in the winter.
Indeed, I had high oil temps. I topped it around 254 F while towing a 5th wheel in the Alabama summer with no noticeable defueling. I wouldn't have pushed it that far without running synthetic oil.
Regardless, I relocated after replacing my oil cooler the 2 time already. I say all that to say I'm not surprised by those oil temps when a shop says they "flushed" the coolant system. They'd go broke doing it right.
Just last week I noticed my EOT and ECT at 35 degrees going 65 and unloaded. I had a 5th wheel trip in two days. Pulled the relocated oil cooler, soaked it in alcohol over night, back-flushed it the next morning and reinstalled. My deltas while towing got up to 4 degrees running 75 mph, ac on and towing the 5th wheel. I'd relocate and move on with life.
REcommendations:
1) Like Jester said. These things have an oil cooler bypass valve that will cause your issue. It's in the bottom of the oil filter housing. Check it. You can replace just that. There is also an oil filter bypass valve, but that won't cause high EOTs.
2) If the oil cooler bypass valve looks good, relocate that puppy. You have more important things to worry about.
Indeed, I had high oil temps. I topped it around 254 F while towing a 5th wheel in the Alabama summer with no noticeable defueling. I wouldn't have pushed it that far without running synthetic oil.
Regardless, I relocated after replacing my oil cooler the 2 time already. I say all that to say I'm not surprised by those oil temps when a shop says they "flushed" the coolant system. They'd go broke doing it right.
Just last week I noticed my EOT and ECT at 35 degrees going 65 and unloaded. I had a 5th wheel trip in two days. Pulled the relocated oil cooler, soaked it in alcohol over night, back-flushed it the next morning and reinstalled. My deltas while towing got up to 4 degrees running 75 mph, ac on and towing the 5th wheel. I'd relocate and move on with life.
REcommendations:
1) Like Jester said. These things have an oil cooler bypass valve that will cause your issue. It's in the bottom of the oil filter housing. Check it. You can replace just that. There is also an oil filter bypass valve, but that won't cause high EOTs.
2) If the oil cooler bypass valve looks good, relocate that puppy. You have more important things to worry about.
Fleet Mechanic
Joined: Jul 2018
Posts: 1,629
Likes: 103
From: Jacksonville Florida
If you sit back and read alot of the threads on here and read up on the 6.0 in general, there really a simple motor.
I do agree with the Guys in saying you got one with alot of issues. Eh, if your not afraid to get your hands dirty and do some reading. I think you can do it. They are really a simple motor to work on.
As far as the oil cooler. I bought an upgraded oil cooler a few years ago and installed it. I still have Deltas within 5 to 15 Degrees no matter what i do. I have never seen 250 degrees, 220 maybe, and i tow some heavy loads (Granted i do live in Florida)
I do agree with the Guys in saying you got one with alot of issues. Eh, if your not afraid to get your hands dirty and do some reading. I think you can do it. They are really a simple motor to work on.
As far as the oil cooler. I bought an upgraded oil cooler a few years ago and installed it. I still have Deltas within 5 to 15 Degrees no matter what i do. I have never seen 250 degrees, 220 maybe, and i tow some heavy loads (Granted i do live in Florida)
Thread Starter
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5th Wheeling
Joined: Jun 2025
Posts: 28
Likes: 8
If you sit back and read alot of the threads on here and read up on the 6.0 in general, there really a simple motor.
I do agree with the Guys in saying you got one with alot of issues. Eh, if your not afraid to get your hands dirty and do some reading. I think you can do it. They are really a simple motor to work on.
As far as the oil cooler. I bought an upgraded oil cooler a few years ago and installed it. I still have Deltas within 5 to 15 Degrees no matter what i do. I have never seen 250 degrees, 220 maybe, and i tow some heavy loads (Granted i do live in Florida)
I do agree with the Guys in saying you got one with alot of issues. Eh, if your not afraid to get your hands dirty and do some reading. I think you can do it. They are really a simple motor to work on.
As far as the oil cooler. I bought an upgraded oil cooler a few years ago and installed it. I still have Deltas within 5 to 15 Degrees no matter what i do. I have never seen 250 degrees, 220 maybe, and i tow some heavy loads (Granted i do live in Florida)
Fleet Mechanic
Joined: May 2010
Posts: 1,480
Likes: 161
From: West by God Virginyuh
Yeah, I hear ya…now that you’ve got a 2021 vehicle, which should be reliable, I’d do the 6.0 flush properly, replace the oil cooler, and sell it. And that’s coming from a guy who’s had his 6.0 Excursion for 11 years and counting…though I’m probably gonna sell mine soon as well. Lol
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