This might be a silly question.

The delta between ECT and EOT should be less than 15 degrees when fully warmed up running 65mph on level ground for 15 minutes.

Under these conditions my truck will consistently have a 9 degree differential.

However, if I drive for say 30 minutes to an hour at 65 on level ground my delta will be around 11 - 15 degree differential and stay there regardless of how much longer I drive.

This is pretty consistent regardless of outside temperature.

Is this normal and which differential should I consider when considering the delta for oil cooler health purposes?

 

You should use the 11-15* delta as your reading.

 

Yep. And towing will make that even bigger, start saving for a new oil cooler, it's in your near future.

 

Thanks for the reply's.

You might be correct about a cooler in my future but these numbers have been this way for the last 100,000K miles and I do occasionally tow around 9,000 lbs.

The oil temp has never gone over 221 and my summer temps here in N. CA average 100 degrees every day for months!

Probably just jinxed myself now!

 

My ECT-ECT was steady at 10-12 degrees for the last 5k. On hot days, the difference was over 12 degrees.

I took Randy Watson's advice and worked a lot of over time at work and spent the money for new egr cooler, oil cooler, HPOP, and few other parts.

Expect to find other issues once you start working on the replacement. I spend another $500 on things that really needed replacement.

Labor from a Ford Diesel Master Tech moon lighting was $1000. Vans are a PITA to work on.

Find a real diesel mechanic. Don't go the guy that sometimes works on the 6.0.

I got my van back yesterday and drove it hard for an hour and the difference stayed between 4-6 degrees even while climbing a steep grade. The oil cooled much faster on the descent.

Have your turbo checked since you have to remove it. I put on a new unison ring as it was tweaked.

 

Mine runs 11-12 towing or empty for the last 40,000 miles, it just runs a little warmer towing.

 

Man I was just wondering this. My truck since I got it has never been driven for more than 45 min to an hour and my deltas were always at most 5° difference. But the other day we took it to myrtle beach and back (3.5 - 4 hrs each way) and my temp spread went up to 10-11° difference!

I'm wondering if it's really a prob though like you said. The test of driving for 20-30 min on the highway at a consistent speed gives me perfect results everytime..... I think my thermostat is opening to soon though which prob effects the results, ECT is always in the high 180s

 

Mine runs 188 ect with ac off and 190-192 with ac on and empty. Towing it will run 194-200 depending on weight. Oil temp is always 11-12 above coolant. Low deltas on short runs are normal, it takes a while to heat up 1000lbs of steel, just because the oil and coolant are up to temp doesn't mean the whole engine is that temp.

 

It's probably hotter.

 

I wouldn't stress over getting the oil cooler addressed immediately, unless your towing consistently. But I do second Watson's advice as to saving up for it.

I am right there with you, I am always 9-11 degrees, and I am a happy 6oh owner.
Some people have or can get the funds to bite the bullet early. Good for you Coolfeet, still love reading your mileage on your sig

If and/or when my spread starts to hit 15 degrees, then I will be saving up.

 

I'm a worry wart myself but 100k with 11-15 split and been that way for the duration I'd say you're good. Now if it was 5 then has been creeping up over time then I'd be looking and as the others said I'd be saving the funds (it's not too bad especially if you can do it yourself ) I've read on here where some have had an 11 or higher split since new and stayed that way.

 

So I'm taking my 1st empty highway drive in a couple years and figure I'll just watch that delta between oil and coolant (I have a gauge in Torque so it is just a glance). 65 on cruise and I was getting consistent 7 degrees -- man what do these folks do that get 2 - 3 degrees?! Why they get a Mishimoto thermostat, that is what they do...!!!!

My ECT would sit rock solid at 190.4 and EOT and 197.4...

So I found a cheaper alternative to the Mishi thermo... Turn on your AC!

Yup, brought my delta to 5 to 6 degrees -- so if floating your boat is raising your ECT to get a lower difference to EOT, because you are pushing your coolant system harder. Save sum bux and just hit the ol' AC button -- raised my ECT to 192 and my EOT stayed at 197.

Go figure... And I thought thermodynamics was a complicated engineering thing...

 

So many people are hung up on these numbers and I think, miss the reason to watch the difference. There are other factors at play and can be the deciding factor in a cooler replacement..... the EGR cooler.

As the oil cooler becomes less efficient, that coolant is passed to the EGR cooler, at a higher temperature. Less coolant flow at a higher starting temp can cause the coolant to flash to steam. We can't really see that, except
we do see a gooey mess or moisture in the EGR cooler. We know that hot material expands, may have small cracks and then the fluid is potentially exposed to direct contact with hot exhaust gasses. Anybody test the thickness of the coolant tubes in an EGR cooler? I wouldn't be surprised if they were fairly inconsistent and that damage can occur earlier. A hot day, tow the boat up some hills, it's not that heavy, you lay it down and hit 20° from an average of 11-15°. Truck cooles immediately after cresting the hill..... do this a bunch of times over the year and the coolers damaged.... what happened my difference was only 11° consistently.

At that difference, I'd be watching not only the gauge but the internals of the EGR for moisture and checking that often, remove the valve and have a peek.

A delete kit changes everything, but there is still a risk of overheating and oil cooler rupture.
I wouldn't run a mishimoto tstat unless everything's running great and your on top of monitoring everything to maintain it at that level.

I run one, my trucks deleted, my oil cooler is 49k since replacement, run EC-1 coolant, flush at 30k miles, no coolant filter and my difference is 1-4° on the 15 minute run. 4-6° all out highway on big trips and towing the 8k trailer it's 6-10°.

It's about efficiency, if it's doing a good job, then watch it and when it starts to show signs of less effective cooling.... then do something about it. Be proactive and don't wait until it becomes a serious issue.... very often what we see here in the forum. Guys show up here asking if it's to late already know the answer.

 

Some people have run those numbers for years and they never got worse. I would just keep an eye on them and wait for a spread change that may never happen.

 

I really appreciate all of the feedback!

One additional item to my post that started this thread, I do have a BPD EGR cooler in the truck in place of the OEM Ford one.

The oil cooler is Ford OEM and I have a coolant bypass filter installed.

Would the switch from a Ford EGR cooler to a BPD EGR cooler change the acceptable delta spread in a 6.0?