Adding a DEF Coolant Loop Shut-Off Valve

[LWBAZ]

In this thread…

https://www.irv2.com/forums/f278/k2-...mp-547033.html

…several of us were discussing DEF temperature readings. Also mentioned was the possibility of a valve failure; specifically the valve that is only supposed to open in really cold weather, thereby allowing hot engine coolant to circulate through the DEF head so as to prevent the DEF in the tank from turning to slush (or worse).

Looking at that particular valve on my 2018 Entegra Cornerstone, it turned out to be smaller than I expected and didn’t appear to be particularly robust. Since we very rarely travel in extremely cold weather, I decided to add a quarter-turn ball valve that will allow me to ensure that hot engine coolant is not circulating through the DEF head unless I want it to.

Attached are some photos. The first one shows all the parts I used, except for about four feet of 5/8” blue silicone heater hose which I also needed to purchase. The second, third and fourth photos show the tags from the ball valve and the hose barbs I purchased at our local Ace hardware store.

The fifth and sixth photos show the completed project with a few notes added for clarification. Any questions or confusion, feel free to ask.

[R.Wold]

I like it. Just curious how you determined the input side - guess there was still pressure in the line? Not sure on a Spartan chassis with a Shaw head, but on a Freightliner DEF head it’s apparently easy to confuse the two, with some coming from the factory reversed, and some techs hooking them up backwards after replacing a DEF head.

[LWBAZ]

Originally Posted by R.Wold

I like it. Just curious how you determined the input side - guess there was still pressure in the line? Not sure on a Spartan chassis with a Shaw head, but on a Freightliner DEF head it’s apparently easy to confuse the two, with some coming from the factory reversed, and some techs hooking them up backwards after replacing a DEF head.

Fortunately, the Shaw DEF heads include labeling on the head indicating coolant inlet & outlet and DEF suction & return.

The first of the attached images shows which is which. The second image is an actual photo of a Shaw DEF head. You can almost see the arrows on each port, indicating the direction of flow for coolant and DEF.

[R.Wold]

well at least they did something right.....

[LWBAZ]

Here's a photo of the DEF head on my coach with labeling indicating which line is which.

[LWBAZ]

Originally Posted by R.Wold

well at least they did something right.....

Yes, I agree. But I would gladly trade the clear & precise labeling for a reliable DEF head!

[buck58]

Great Thread!! Thanks so much for the information & detailed description of the parts and work…✝️

[brobox]

Nicely done Larry and thank you for the great share. I'll bet that bit of owner ingenuity cost less the Spartan paid in labor for one DEF head replacement. It would be interesting to run the tank heat test after the installation to see how much of a difference there is.

[Gary.Jones]

Since we are all aware that there are a lot more sensors in the DEF system than any one engineer would have thought to design, are we reasonably sure that there isn't a "flow sensor" also included in that mess?

Larry, how about driving circles around Phoenix for a couple of days to make us reasonably sure that you didn't just guarantee that you are now certain to get the notorious DEF Head failure codes at some random time or distance....

Please report back before I buy my valves. --

Gary

[J Gunter]

Looks like a great job Larry. 2020 and on would be a little harder since the Valid air manifold sits right above the def tank. I’ll have to look at mine again, but I’m sure the Valid manifold would have to be taken loose and tied up to gain access to the coolant line.

[dave&ginny]

Larry,


great job and thanks for the pictures.

[Archer2]

That looks really good. Since the OEM valve should never be open unless the DEF is frozen, which is not likely to happen in a Arizona anytime soon, the added “insurance valve” can’t hurt, right?
Anyway that’s a very neat job.

[ThunderRidge]

Careful out there.

From the Cummins Owners Manual.

Even though DEF freezes at approximately 11F, the SCR system is designed to be frozen and thawed. The DEF tank is heated by engine coolant, and the DEF lines and after treatment DEF dosing unit are electrically heated. No operator interaction is needed when operating in cold temperatures; heating and thawing are controlled automatically by the ECM.
After turning the key switch off on a vehicle with SCR, a pumping sound may be heard from underneath the vehicle. This sound is the aftermarket DEF dosing unit recirculating DEF through the system and returning it to the tank. This is normal system operation. The recirculating process may take up to 15 minutes to complete. To avoid system damage, do not disconnect the vehicle batteries during this process.

It is unlawful to tamper with, modify, or remove any component of the SCR system.

[Tim Fox]

Larry
Nice job and as usual, great write up.