When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Oh well, this discussion just took a turn in another direction. This morning, 14 degrees out and block heater plugged in, it wouldn't start with the remote start. I went out and started it and it took a couple of extra seconds. Drove it to both schools. It was up to about 180 ECT. Pulled out on the highway and went to stand on it and NOTHING. No turbo, no power, just flat. I got up to 40mph and made it back to my street. The HPOP was only making about 575 and would not go higher. Scanned it and got the code for injector control pressure. Got to the driveway and tried to run it up in P, but it just wouldn't show any ICP over 500. Turned it off and it would not restart. FICM was 48V. Called the shop, they sent a rollback. It started and backed out to the street but died when he tried to drive it onto the rollback. So, its gone to the shop.
Thanks. Money-Pit PM'd me and referred me to that thread - I hadn't kept up with it.
Not doubting it happened for some folks, just would like to know the mechanism because if a temperature differential is reduced, then it pretty much seems to me that the flow through the cooler had to change (increase) since the heat exchange area of the oil cooler is constant. Not sure how that would happen, but I can accept that it does for some situations.
The ECT is the hot water temp and the EOT is the cold oil temp. So, if you raise the overall water temp (and keep the coolant flow the same), then I just can't see anything happening other than the oil temp going up also - by about the same amount.
Q=U*A*delta T (for the engineering background). You simply can't remove more heat (actually enthalpy) from the oil (reduce it's outlet temp, or even keep it the same) with warmer inlet water unless the flow changes.
If there are flaws in that thinking, I certainly would not mind hearing what they are and how it would support a reduction in the ECT/EOT differential.
Thoughts?
Originally Posted by Bullitt390
I would tend to think the coolant flow is reduced with a hotter t-stat allowing more heat transfer from the EOT.
See a similar concept with the old Ford FE engines (360, 390, 427, 428 etc). Many think they can run 160 degree t-stats versus the stock 180 and the engine will run cooler.
Nope, what actually happens is the engine ends up running hotter since the t-stat is open further causing the coolant to flow faster thru the radiator. Not as much heat transfer and the end result is coolant temps topping 210 or more.
So, what does a person do? Install a 195 t-stat and it stays at 195. T-stat remains barely open, reducing flow and allowing the radiator to do it's job.
That is one example.
Not much different than the Sinister oil cooler with the bigger internal passages. Too much flow and not enough saturation time which equals hotter EOT.
Josh
Aren't there essentially 4 parallel circuits of coolant flow in the 6.0, starting from the coolant pump?:
1 Through the thermostat>radiator>back to pump
2 Through the driver's side of the block>back to pump
3 Through the passenger's side of the block>maybe heater core?>back to pump
4 Through the oil cooler>egr cooler>intake/egr valve manifold>back to pump
I haven't gotten into the pump, but I assume it steadily moves fluid at a proportional rate to rpms. So one variable would be the thermostat's flow restriction. The pump is moving a given volume per rotation, and as the thermostat restricts the flow though the radiator circuit, then the flow through the other three circuits should increase.
Now we've all seen the cutaway photos of oil coolers with their baffled aluminum passages. So there is lots of opportunity for heat transfer. Assuming those passages are mostly open, it stands to reason that forcing more of a relatively cooler fluid through the oil cooler will take more heat away from the hot oil in the adjacent levels. It doesn't seem that much of a dwell time is needed with that much surface area in such an excellent heat conductor, just a relative difference in the counter flow fluids.
So, unless I'm missing something here, it seems plausible that a higher temperature thermostat(t-stat that presents more restriction in the radiator circuit, therefore more in the other circuits) can reduce the margin between oil and coolant temperatures.
Oh well, this discussion just took a turn in another direction. This morning, 14 degrees out and block heater plugged in, it wouldn't start with the remote start. I went out and started it and it took a couple of extra seconds. Drove it to both schools. It was up to about 180 ECT. Pulled out on the highway and went to stand on it and NOTHING. No turbo, no power, just flat. I got up to 40mph and made it back to my street. The HPOP was only making about 575 and would not go higher. Scanned it and got the code for injector control pressure. Got to the driveway and tried to run it up in P, but it just wouldn't show any ICP over 500. Turned it off and it would not restart. FICM was 48V. Called the shop, they sent a rollback. It started and backed out to the street but died when he tried to drive it onto the rollback. So, its gone to the shop.
Sorry to hear that. I've been there.
About this time last year I was looking for a shop to do some work on my engine beyond what I can practically manage myself in my garage that I can't even fit my truck in. I knew for sure my oil cooler was due for replacement.
One day I was headed to work and, as I rounded a corner and got on it to get up to speed on a highway entrance ramp, it suddenly went flat, would just barely get along. I had to hobble down the shoulder to make it to work. I tried creeping home after work, but didn't make it. Just died. I initially thought it was gelled fuel because I forgot additive on my previous fill up. Took me the longest time to figure out it was my HPOP. Main seal popped out at the drive gear.
Any word back from your shop?
Looks like you pretty much already know it's your HPOP?
Since they're in there you can go ahead and replace that oil cooler. But I'm still interested in the debate going about the thermostat in your thread.
The shop called Friday and he had tested the pressure through the ICP and the bad news was its the oil cooler. So yes, I'm doing everything that I could think of while he has it, which includes a new oil cooler and new t-stat. The unfortunate thing now is we won't be able to determine if a new t-stat closes the gap between ECT and EOT because with both a new cooler and a t-stat the problem should be corrected (if it existed). However, if I get the truck back this week and it runs perfect and I still have an 11 degrees spread between ECT and EOT, I will feel better that before the HPOP failed I had decided not to replace the oil cooler until the spread got larger. I'll make sure to update when I get it back and after I have a chance to take it on the interstate to see what happens.
Aren't there essentially 4 parallel circuits of coolant flow in the 6.0, starting from the coolant pump?:
1 Through the thermostat>radiator>back to pump
2 Through the driver's side of the block>back to pump
3 Through the passenger's side of the block>maybe heater core?>back to pump
4 Through the oil cooler>egr cooler>intake/egr valve manifold>back to pump
I haven't gotten into the pump, but I assume it steadily moves fluid at a proportional rate to rpms. So one variable would be the thermostat's flow restriction. The pump is moving a given volume per rotation, and as the thermostat restricts the flow though the radiator circuit, then the flow through the other three circuits should increase.
Now we've all seen the cutaway photos of oil coolers with their baffled aluminum passages. So there is lots of opportunity for heat transfer. Assuming those passages are mostly open, it stands to reason that forcing more of a relatively cooler fluid through the oil cooler will take more heat away from the hot oil in the adjacent levels. It doesn't seem that much of a dwell time is needed with that much surface area in such an excellent heat conductor, just a relative difference in the counter flow fluids.
So, unless I'm missing something here, it seems plausible that a higher temperature thermostat(t-stat that presents more restriction in the radiator circuit, therefore more in the other circuits) can reduce the margin between oil and coolant temperatures.
I think your assessment is a very plausible explanation (even though the coolant is a little hotter, if it has more flow, then you could see a reduction in the differential). If the heat exchanger is partially plugged, then extra flow could certainly help (again - if you actually do realize extra flow). Well said.
It's all finished. I picked it up tonight but I forgot my bluetooth dongle so I couldn't use my gauges. The shop owner said the EOT was within 2 degrees of the ECT on the shake down after he finished it. He did say it was running around 190 with the new t-stat. The outside temp is still around 25 so that's 10 or 11 degrees warmer than before.
I made the first drive this morning with the gauges on. The picture is after I turned into my street and parked in the drive, so it had cooled down a few degrees. It was running 190 ECT and the oil had not caught up yet. Before on the same run, the ECT would not get over 179.6 and the oil would be 7-8 degrees warmer.
