Coolant system and temperature delta. I want to share my experiences over the last six months with coolant system on a 2006 132K Ford F2 50. I got the truck at a salvage auction and have no background info beyond the mileage. In September I drained the coolant system. The coolant that came out of the truck at that time was green. I did a chemical free coolant flush as outlined in the tech folder. At the same time I did a compressed air/water backflush of the oil cooler.
Distilled water was used for the last three flushes. CAT coolant was used after Flushes.

I had been monitoring the Delta value between the oil temperature and the coolant temperature prior to the flush and swap. Using the 20 minutes, 60 mph, flat Road technique the dealt it was 14° both before and after flushing swap.

In October I installed a bypass coolant filter. I continued to monitor the Delta values over the next 1000 miles. At the end of 1000 miles I did another 20 minutes, 60 mph, flat Road delta measurement and now the Delta is 10°.

I don’t claim to understand what has happened. This does not appear to match up with the experiences of other forum members. Are there any theories out there as to why I am seeing these numbers? I can’t think of a good reason for the Delta to drop after I began filtering the coolant.

I’ll run another thousand miles or so and then post the next delta value.

 

Interesting. I've picked up a couple 6.0 at salvage auctions in the past 6 months.
I'll follow along to see what happens....

 

Buys a 6.0 at auction is like spinning the roulette wheel. Not for the faint of heart.

 

Ambient temp is a factor (you didn't mention what that was during your runs) as well as the new coolant is supposed to have better heat transfer - 4 degrees is way more than I'd expect on the latter. Maybe some crud freed up from your oil cooler with time?

 

Was there a significant difference in ambient temps between the two runs?

 

I don’t think ambient temps were more than 15 degrees apart. I t may have been that the actual oil temp was higher for first run than the more recent one. I think that the delta is a few degrees higher at oil temps under 200 than when the oil temp is over 200 (reduced coolant Viscosity at higher temps allows it to flow through partially clogged oil cooler better?)

 

Dan. Thanks! The coolant was the same for the post flush run and the most recent run. Wouldn’t that be great if some crud freed up. Maybe another full flush and oil cooler backflush with compressed air/water would free up some more? From what I’ve read, the “standard” oil cooler clogging stuff (silicates?) are in there forever once formed. Maybe my coolant crud is different than the oil cooler clogger that begins the profession of EGR failure followed by head warp.

 

Thing is, you weren't running the gold coolant before - that stuff causes the hard deposits - no idea what green does in a 6.0, maybe leave a deposit that can be dissolved?! You're heading in the right direction anyway, and 10 degrees isn't all that bad, mine will run 6-9 at around 65.

Another thought is what is your coolant temp at when running the test? I've had some variability if it is still in the range that the thermostat may be opening/closing (which tends to be under 190 deg coolant temp) - once I hit 194 is when I start paying attention to the oil/coolant difference...

 

There is no rhyme nor reason to coolant temps IMO. New cooler, radiator, flushes, EGR high flow cooler installed, coolant filter, tried external oil cooler for a while, thermostat, new degas and I still run 8-9 delta but I rarely get over 14 delta towing.

 

8-9 degrees is healthy, no reason for concern.

 

Im normally between 8 and 9 on my 05. Only thing I’ve done is coolant flush and filter install.