ECT/EOT Delta silly question
Fleet Mechanic
Joined: Oct 2012
Posts: 1,558
Likes: 26
From: Bay Area
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.
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.
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.
I systematically started replacing things that needed replacing. I flushed the entire cooling system with Restore, replaced the Ford OEM thermostat with a Ford OEM Tstat. I ran CAT EC-1.
My EOT-ECT difference was steady 10-12 degrees until the ambient temperature was in the 80s-then it sometimes would go up to 15 degrees difference. With ambient temperature in the 80's, the ECT was consistently at 205 and ECT 220. I knew had cooling problems.
I saved for the oil and egr cooler and HPOP.
After replacing the oil and egr cooler, I experienced a drop from a 12 degree difference to a 4-6 difference.
The Ford Tech said my EGR cooler probably was ruptured as the EGR valve was too clean.
As many people have pointed out, the temperature difference does not tell the entire story. Nobody drives on flat roads all day at 70 MPH. My driving habits are different than another. I use my van for camping trips in the mountains. I climb steep grades and push the EOT up to 225 and beyond. Both the oil cooler and egr cooler have no idea about "delta". It's heat that kills these items. What if I ran at 250 EOT and 245 ECT all day? My delta is 5 degrees, so I must be okay. If I thought in terms of difference of temperature only, I would see a lot of things failing in my van.
Post Fiend
Joined: Sep 2006
Posts: 7,426
Likes: 6
From: Sioux Falls, SD
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.
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.
Tuned
Joined: Jun 2011
Posts: 259
Likes: 0
From: West TN
the purpose of the delta test is to find out if your oil cooler is becoming or has clogged. I think a parallel test to go with it is to watch the delta as you decelerate from the test run. Coolant will come down quickly. If oil temp lags by much, then the cooler should be suspected. If the oil comes down hard right with the coolant, then your deltas are just a little high but you don't have a problem.
Mountain Pass
Joined: Mar 2013
Posts: 224
Likes: 1
the purpose of the delta test is to find out if your oil cooler is becoming or has clogged. I think a parallel test to go with it is to watch the delta as you decelerate from the test run. Coolant will come down quickly. If oil temp lags by much, then the cooler should be suspected. If the oil comes down hard right with the coolant, then your deltas are just a little high but you don't have a problem.
i was hoping someone would agree with me on that! Makes me feel better about my 12-15 delta cruising down highway. When I slow down, within a minute or 2 of getting off highway I’ll be 10 degrees or below. If I pull up to let’s say a drive thru, and sit about 5 minutes. Spread goes about 3-5 degrees. Had my cooler backflushed and got a lot of junk out of it, temps didn’t change but at least I know its cleaner. Seems to be doing it’s job making sure oil doesn’t get too hot. 15 degrees means it could be clogging, my mechanic told me his truck has been running 15 degree deltas ever since he got it 2 years ago. Just have to monitor the oil temp and trucks are deleted so there is no EGR cooler to worry about.
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Mountain Pass
Joined: Mar 2013
Posts: 224
Likes: 1
i was 7-9 for years until my last oil change then it suddenly when up. Keep your fingers crossed mine will still be good! I’m driving it 1100 miles next week to Texas. Hope it all goes well
Fleet Mechanic
Joined: Nov 2012
Posts: 1,347
Likes: 110
From: Lakeland, Fl
Did you change brands and or viscosity? I see lower deltas with Delvac 1 5w40 than with 15w40.
Senior User
Joined: Oct 2010
Posts: 276
Likes: 2
From: Bonita Springs FL
Maybe my truck is weird, but my Deltas are lower when I tow my 10k lbs boat. Both temperatures jump up about 8 degrees from unloaded, but the deltas drop from 8 or 9 to 4 or 5 when towing the battle wagon.
Logistics Pro
Joined: Jul 2014
Posts: 4,673
Likes: 531
From: Houston, Texas
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.
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.
Hotshot
Joined: Jul 2003
Posts: 12,177
Likes: 40
From: Newport, WA
I just finished up a bunch of work on mine, including a new oil cooler. Running 65mph on as flat of ground as I can find around here, I was typically at a 5.5 degree delta (194 ECT, 199.5 EOT). Good enough for me... the real test will be when I hook the camp trailer to it in a couple weeks.