Here is my set up Jack.




I am also running a Mishi 200° T-stat, Motorcraft radiator, OE oil cooler, and I so have the vaccum valve on the heater line. Not sure about the water pump. Plus I have a snow plow fan clutch and I removed the stator.

 

I was going to write we would have to put a pressure transducer in the return line to see if the pressure was high, but that's exactly what you are doing.

 

Jack you got me thinking about coolant flow a little bit. I tee'd my bypass filter into the heater core supply hose. When I tow most the temp I do have the AC on, so let's assume the vaccum valve is closed. Now all that coolant that normally goes to the heater is going to the filter and right back to the coolant over flow hose. The system was designed to be deadheaded when on max ac, That flow would then be redirected through the other cooling passages, ie the oil cooler and block. Those passages would be a longer pathway back to the pressures transducer, thereby smoothing out or eliminate the pressure spikes caused by the increase in pump speed. While a centrifugal pump like our water pump can operate with upto 100% slippage, it does increase pressure with increased speed. Now with the current set up I have I must be seeing the instantaneous pressure as I am getting full flow from one of the flow paths.

By eliminating the flow from the heater flow path start to my pressure sensor, I smoothed out the pressures inadvertently.

The funny thing is that I haven't done anything different with my set up then a lot of other people. I don't know why I see different pressures. But changing the flow path definitely lower my overall coolant pressures.

 

That's where I was theorizing, too. And why I brought up how we all plumb these in. But I don't tow as you do, I don't see the ambient temps you do, and there is some variability in all these setups. Mine is homemade, and the filter is set up in front of the driver's tire, so my hoses are long and could diminish pressure. Plus, I never ran a coolant pressure gauge constantly, so I never saw anything if there was. The setups like the XDP one have short hoses. Plus, you always have vehicle-to-vehicle variability. Block and head casting variations possibly.

For example, we would buy 2 or 3 vehicles for major test programs as we did with the Superduty program. There were slight differences between those three in braking performance. We always saw that with any platform. After we got the contract, I would pare down to one, and that vehicle may be with us for 10 years, transitioning from OE programs to the aftermarket. We would keep it to have the same data platform, so tests years later were relatable. We saw the same with brake dynos in the lab. Same with test procedures. Our city traffic work had repeating loops. On one of the last Explorer tests, before the facility was shuttered, a certain material would develop brake noise on the third of five loops; you get to one operating heat soak condition.

N of 1 can be a variable, but you pair it with someone who has good observational skills, you can find something. Is it the change in flow, different filters, hose paths, the position of the moon? The coolant filter setups were never evaluated in the OE world under all the auto manufacturer tests conditions. All we (you) can do is A/B the situation and find the consistency in that, and then other people who have similar observations also A/B test and see if the results are the same. I have great respect for the engineers who work in the cooling field; there are things done that has me scratching my head.

One example is why with the 6.4L block, they put different size restrictions in the pathways from the water pump/front cover to the block jackets, with more flow to the passenger side. The 6.0L block has a ledge cast in the block for them but never installed, and the ports between the two engine blocks are the same. Why did they do that; to slow down the flow? The flow goes to the block's back, then to the heads, and back to the front cover.






We can go back to what AKBlackfoot saw with his truck, puking after a rebuild with going upgrades with a tune. The cure being installing the coolant degassing ports at the back of the heads. There's a lot of things that are unseen until someone finds them. That one didn't make sense to me when I first saw it, but my heads are drilled for that modification, just in case.

 

Maybe the orifice size is too big. It is supposed to be small for bypass purposes.

 

Good thought. The IPR full flow coolant filter goes back through the heater core with most applications.

 

The IPR Research is the system I drive. At working temperature, my permanent pressure monitoring shows this. At strong, longer loads the value rises to 15-16psi (ECT dependent).

 

Just a quick mention, in the past I did see very consistent pressure rises with both temp and rpm. This trip I didn't seem to have the rpm variable. My pressures did rise with temp as normal but they were about 2 to 3 psig less then before. I observed no pressure increase with RPM. Before I was good with a consistent jump in pressure with a downshift.

When I get home from this trip, I'll repeat the RPM vs pressure test I did in the past. I'll do it with the coolant blocked off and then flowing.

Should be interesting. If it does what I suspect I might change my operating procedure, leave the valves open most of.the time and.close them if I will be towing.

 

Jack, in looking at the differences in the 6.0 to 6.4 flow paths, I wonder if the engineers were trying to slow the flow down into the block. Coolant needs a certain about of time to get the correct heat transfer into it, too fast and it doesn't pick up enough heat. I get the different restrictor sizes. I think that is to balance the flow between the two sides. Also, if I remember correctly the 6.4 has a larger water pump. So that pump would flow at a higher rate, and would flow more liquid out one side then the other.

 

Should be interesting.

 

Yes, it has a larger water pump...and restrictors. But, it's like during the test trials, after the decisions were made about upping the pump size (as they did with the post '03 engine), they had to punt, slow the flow. The different orifices are what got me to wonder if the heater element in the back of the passenger jacket was causing an imbalance in the flow through the two banks.

 

https://www.eng-tips.com/viewthread.cfm?qid=364290

 

I wonder if installing those in a 6.0 block would help balance out the flow? B.

 

The coolant filter discharges to the degas bottle which isn't full of water and is the suction point of the pump, so I don't see how that could increase the pressure in the degas bottle.

Perhaps you are getting a lot of coolant bypassing the radiator thru the coolant filter which is raising the water temp & along with it the pressure.

I design large building heating/cooling systems utilizing water for a living. Very similar system. Typically the pressure at the pump suction (degas bottle on our trucks) is a constant and doesn't change with pump operation. the pump is sucking & pushing back into the same place so the pressure equalize. It only changes with temperature. I'll try and sketch up a simple diagram tonight when I get home.

Need to install a pressure sensor on my degas as I run similar conditions (big load, high temps, long grades).

 

I'm not sure that only the bottle pressure is high, but somehow altering flow distribution, maybe overheating in an area, elevating the pressure throughout. I just don't know......

I think we'll have to see if the condition is consistent with the valve operation, but without someone who really understands this, the answer may be elusive. I think we need Nikola Tesla.