Have a stock 2005 F250 6.0 superduty FX4 diesel with 164,727 miles on it. I was towing our 2-horse trailer recently and after about 30 minutes of driving the wrench light came on the instrument panel. Was a cool day, about 62-65F out, and the driving was mostly on the flat highway at 60-65 mph.

The truck's manual said the wrench symbol is a warning light (can't recall the name) and had something to do with "limp home" mode. The truck drove fine, but I plugged in my ScanGuage II to see if any codes were present.

The ScanGuage II didn't read any codes (which is not to say no cods were present, just that it may not have been able to read them). I Googled the wrench symbol and saw a myriad of possible issues from an accelerator sensor fault to a problem with the turbo charger system to possible EOT/EOC issues.

Since I had programmed my Scanguage II to read EOT & EOC I thought I could rule out an issue there by seeing if the temp difference was within the acceptable ~15 degree delta. It wasn't. EOT was 225F and EOC was 195 (30 degree delta).

I wanted to test the EOT/EOC without a load so the next day took the truck for a few short ~15 miles drives throughout the day. No wrench light when I turned the truck on, but after about 15 minutes of driving each time the temps were:
Trip #1: EOT 201/EOC 192 (9 degree delta)
Trip #2: EOT 207/EOC 182 (15 degree delta)

The next day took the truck for a few longer ~30 miles drives (again without a load) throughout the day. No wrench light when I turned the truck on, but after about 30 minutes of driving each time the temps were:
Trip #1: EOT 218/EOC 197 (21 degree delta)
Trip #2: EOT 220/EOC 190 (30 degree delta)

So shorter trips the temps seem fine, but once the engine warms up more on a longer drive the difference between EOT and EOC becomes greater.

I haven't had the truck at the dealership for maybe 2-3 years, but the last two times it was in was to replace the high pressure oil pump (sometime 1-2 years ago) and turbo charger's unison ring (sometime 2-3 years ago). I service the truck's basic myself (oil+filter changes, fuel filter changes, EGR cleaning, etc.) on a very routine schedule. ~2,000 miles ago the oil+filter were just changed and the EGR valve was cleaned.

While the truck seems like it is running fine now, and the wrench light hasn't come back on, I just know if I don't look into this the truck will break down in the middle of no-where when my wife is on her way to a horse show with the trailer and horses in tow.

Whatever the problem is I'm sure it's a $1,500-$2,500 dealership fix (seems to be the going rate these days for whatever the problem is when I take it to the dealership), which is money I just don't have to spare right now. So if its something I can troubleshoot/fix myself, I'd like to give it a go.

Ideas on where to go with this?

 

A new oil cooler is in the immediate future. Go with an OEM oil cooler, you can do this yourself for a lot less money.
Do you live in state that has emissions checks? If not, maybe a good time to do a delete.

Read up on the flush procedure, if you are running Ford Gold it might be a good time to switch to something else like Cat ELC coolant or other brands.

FYI a Scangauge is not the best code reader. Get an ELM 327 to plug into the OBD port and then download ForScan for free to a laptop, or for a few bucks to a smartphone.

Here is one for an Android I use but also works on my laptop, plenty of others out there

 

Long story short, pull the turbo and intake manifold and the oil cooler is under the filter housing. It's a DIY-possible job.

Here's one article i found with some pics: Oil Cooler Overhaul: Rebuilding The Heart Of The 6.0L Power Stroke

 

Dieseltechron (rip) has a video on YouTube of doing it start to finish.

 

I used his video when I changed mine. He sure helped a lot of folks in his short time here. Thank you dieseltecron, rip.

Here's the video:

 

If you've never had your cooling system serviced (flush and fill) you might (MIGHT!!!) get by with a flush with Restore and distilled water and refill with a CAT ELC type coolant. If funds are tight and time is long it's worth a try. There are procedures for this in the tech folder. Good luck

 

No emission checks in my state, how expensive is the delete and is it something that is fairly easy to do by oneself? I would consider my ability/skills for working on my truck somewhere between novice to intermediate. Probably the most complex work I've done was replaced my glow plugs and harnesses. Most other stuff (replaced the serpentine belt, replaced the alternator, etc. I would deem novice stuff).

Instead of the delete (read some stuff that indicates the deletes themselves can introduce a host of new issues) what about installing an upgraded EGR cooler like this one from Bulletproof?

 

Interesting tidbit from that article:

Adds about $400 bucks more to the job, but worth it to not have to possibly deal with this issue in 50,000 miles?

 

Coolant filter install is no more than an hour and pretty straightforward. Drain some coolant, install the manifold, splice in two hoses and you're there. $250 for install is a little pricey IMO.

 

Unless the coolant is poorly maintained, the OEM oil coolers are good for a lot longer that 50k miles. I haven't seen a failure in 196k miles. Simply stated, I maintain the coolant system, I watch the temperature differentials, and I do not worry about an oil cooler failure.

That said, an oil cooler replacement is a lot bigger of a job when the cooler has already ruptured and contaminated the coolant.

 

Question about this procedure, should you drain your engine oil and coolant (drain coolant, or flush it) before starting? It looked like the guy in the video drained the coolant, but not engine oil.

 

[QUOTE=navistarnut;17502689]A new oil cooler is in the immediate future. Go with an OEM oil cooler, you can do this yourself for a lot less money.

Do I need a new cooler, or just clean the existing one and add new gaskets/o-rings (like in the video posted below)? Guess that might not be known until I get to the part and inspect it...kinda assuming due to the age of my vehicle I might just be better off replacing the oil cooler than spending the time getting to it only to realize I then need to order the part.

 

You need a new cooler, really no cleaning an old one. Get an OEM Ford cooler.

 

"According to industry experts, the oil cooler on a 6.0L lasts about 50,000 miles before failure rapidly approaches."

I guess I better run out and get a new cooler...I have 143,900 miles on mine, with Ford Gold the whole time but 6 degree deltas tells me I may have some time left before the tear down.

All jokes aside...have any of the industry experts explained how some of these coolers last 3 and 4 times as long as others?

 

When things are stated so vaguely (like "Industry experts") without any actual reference, I will tend to be very skeptical. It truly is about the coolant instead - maintain it and you get good life out of that cooler.