I read a lot about the delta but usually there is no mention of how outside temps would effect the delta.

This time of year with outside temps in to 40-60 degree range, my 2005 F250 will typically run ECT 190 and EOT 198 when testing at 65 mph, flat, etc...

In the summer where outside temps here will be 90-110, my delta will typically be ECT 192 and EOT 211-215 under the same test conditions.

I have a 2 year old OEM cooler, a BPD EGR cooler and a bypass coolant filter.

Ford Gold in the system.

Is it normal for the delta to be "good" in lower temps and "bad" in warmer temps even when the truck is fully warm?

Does this indicate that the oil cooler is bad?

 

From a cooling system and oil system perspective, in general the ambient temperatures are only influencing ECT through air to coolant exchange in the radiator, controlled by thermostat. In the cooler temperatures like winter you might not bump up against the thermostat control unless you are working the motor hard, obviously in summer that is easier to achieve so additional factors come into play as the thermostat opens and the radiator is exchanging water/ant-freeze mixture with air. The ratio of water/anti-freeze mixture does impact the efficiently of the heat exchange in the radiator, even the amount of air in your degas can have some influence.

The heat exchange occurring in the Oil Cooler is fluid to fluid, based upon both Oil and coolant flow for the surface area that is functional to support the exchange - safe to say that ambient temperatures have very little influence here once the motor is up to operating temperature.

So that leaves flow and surface area. Coolant flow is rpm based and controlled by thermostat, oil flow is rpm based and is influenced by IPR pressure and influenced by the oil cooler bypass valve and influenced by the Oil filter bypass valve. The Oil filter housing is the only significant surface area that is exposed to under the hood ambient temperatures as well as operating temperature.

You could really stretch the physics and argue that good flow of oil through the Oil filter housing is actually dropping the temperature of the Oil during the winter months due to the surface area of the housing being exposed to ambient temperatures. I imagine there is at least 24 sq inches of surface area that is exposed to ambient air.

Yes to your question.

As far as the Oil Cooler being bad, Ford has their procedure that the dealerships have to follow when diagnosing - best for you to determine for yourself.

 

I have not noticed significant difference in delta from -30 to 80 except when I added a cover for the grill in cold temp. Then the delta increased. We don't see 100 so I can't comment on the heat

 

At what point (outside temp) do you add a cover to the grill? I've been watching my deltas and they have stayed consistent, but not reaching operating temperature (190+) unless really getting into the throttle on a grade. I'm seeing the same weather conditions as the OP since we are about 9 miles away from each other.

 

Below zero is the only time I need to have it zipped up. Above zero I can zip it which opens a v shape through the middle top of the grill. If I leave it closed above zero or so coolant runs around 200 if I'm putting any kind of load on it.

 

Microbe,

I see a difference in my coolant/oil differential during the winter, both during normal driving and towing. I may see more then others as I don't have the 'stator' in front of motor, as I also saw a decrease in my oil temp once it was removed. But my delta in oil temp is not as great as yours is from ambient delta.

My theory on this has to do with the temp of air engested. An effect I believe has on fuel economy as some well. Since diesel are always "full throttle", there is a lot of air throughput. And while the temperature difference in the air is miniscule to the combustion temps, if we see an improvement in mpg with a 10°F change in thermostat setting then it's possible that air cooling is just as changing. As an example, with some designs the programming is such that an over temp condition with result in cylinder skipping, allowing every other stroke to not fire and throughput ambient air to aid in cooling, something that has saved our Lincoln when its plastic cooling systems likes to fail.

If air cooling was not a factor with diesel, why Is this design of motor (diesel) that needs to utilize radiator blocking so often.

 

I installed a new oil cooler and radiator in September, '16. It was still hot here in SC so I got a fairly good look at the temps.

In the hot weather, mine seems to go to 202 for ECT, around 206 for EOT at highway speed (70 - 80), no load.

In the cooler weather, ECT will go to 192, EOT 194, that's the highest I've seen it this winter.

I have a tube type EGR cooler, new oil cooler, new radiator, 195 deg thermostat, Rotella ELC coolant, new temp sensor, stock tune, stock exhaust.

Our first camping trip isn't until May so unless I pull my tractor somewhere, I won't see much for temps at load.

 

This board is awesome!

Thanks for all the reply's.

All very interesting and informative.

Going to keep studying on this "ambient temperature" stuff just for my own education.

Going to be installing a new Oil Cooler Bypass Valve soon to see what, if any, change that makes.

Truck runs great, no puking ever and my antifreeze looks good and never loose any.

As I said, oil cooler and egr cooler are both two years old (I know that they still could get clogged that fast) and my coolant filter never has any junk in it when changing.

Thanks for all your feedback, keep it coming!

 

I don't recall my delta moving much between winter and summer. I live in east Texas and we have similar temps to you.


I do see about a 10 degree difference in ECT from winter to summer. Winter seems to hang around 190 F, in 90+ ambient summer weather it can get up around 200.

 

Do you run with your A/C on? Are you idling or cruising?

The definition of ambient air temp varies with the situation since technically the variable is the temp directly adjacent to your radiator.

Deltas tend to increase significantly with a hot condenser radiating heat, decreasing the efficiency of the radiator, especially at low speeds and high load.

The fan kicks on at faster intervals to compensate for that extra condenser heat.

 

I was impressed with the quality of the analyses and writing in this thread. There is not a lot of this quality circulating in the world these days either verbal, written or twitted.

That said, I find that with 100K on my truck, I get in the range of 190 - 192 F
ECT vs 199 - 203 F EOT at 65 mph on the flats unladened after the truck is run about 10 - 15 miles. That makes the delta between 9 - 13 F with most of the time falling between 11- 13 F. This delta has been consistent since I bought a Scan Gauge in 2010.

I would be concerned about your hot ambient temperature of 192 F ECT vs 211-215 F ECT which is a delta of 19-23 F.

Was the systems flushed when you replaced the oil cooler? Are you measuring the temperatures with the truck unladened? Have you looked at the bypass filter to see if there are any particulates in it? Good luck and post back with your results.

 

Continued thanks to those that have responded.

To answer some of the questions, With the winter temps the AC condenser would normally be off except when running the defroster to initially clear the window but then it is switched to floor vents which I believe turns off the condenser.

In the summer the condenser would normally be on as I use the AC all the time in temps above 80 (and it is normally 90-110 here in the summer).

The system was flushed with the block plugs out prior to installing the new oil cooler but did not use Restore during the flush.

Temps are being measured after full warm-up and then driving for approximately 15-20 miles on level ground at 65 MPH. The truck is unladen except for the Leer cap/camper shell and a bed slide in the bed (I would guess the bed slide weighs 200 lbs or so).

Recently changed my by-pass filter for the third time and there was a small bit of casting sand in the bottom when I cut it open. Not much the actual filter material.

Going to swap out the Oil Cooler Bypass Valve next just to see if it has any impact (don't really expect much of a change but I figure it is worth it to see if this changes anything on its own).

 

What anti-freeze are you currently using? Hoping a CAT-1 (usually red in color)

Have you topped off with distilled water or tap water?

You can test the current oil cooler for silicant drop out by pulling the cap that is used to reverse flush the oil cooler, insert a white pipe cleaner and twist it around so it can swab the interior, if it is covered with an orange goo/slime/crud then it is time to flush again with Restore taken to 190'F for at least 20 minutes.

 

Assuming the EGR is not ruptured...
Assuming the Oil Cooler is not ruptured....

At 220k I can guarantee that the oil cooler bypass valve is not closing, is not supporting the most efficient flow of oil through the oil cooler under any conditions. Reach out to BulletProofDiesel and ask them to sell you the valve, for about $20 it might make your day.

With that, if you still have a large spread then it is time to think through a different approach.

 

Cooper.Farm, currently using Ford Gold with distilled water.

I'll try the pipe cleaner trick and see what I get.

EGR cooler is a BPD that is two years old, oil cooler is OEM and same age.

The temps have been the way they are now since the new EGR cooler and OEM oil cooler.

Never has gone much higher (only tow a light trailer occasionally).

I am curious if other people have such changes from fall to summer temperatures.

I figured it wouldn't hurt at all to change the Oil Cooler Bypass Valve since it has been in there for over 220K.

Truck runs great, starts good, no smoke, doesn't use any coolant or burn any oil.