Heater bypass

[Packer fan]

I have heard and also saw another post that mentioned that the coyote always has the coolant that goes to the heater circulating. The FFV heater has the flow shut off when the heater isn’t on.
My question is, is it bad for this motor to use the FFV heater set up? Could I put in a T and run a bypass hose so it is always circulating? Or would this make the heater not work very well when I want it?

Thanks,

[Dave Howard]

I have a Gen 1 Coyote in a 2012 MkIV. FFR heater installed with supplied control valve. I did not put in a 4 way valve for constant coolant flow to the heater. I have over 20,000 miles on the car with several longer hour/day roadtrips in the log as well as full on drag strip runs. If the cooling set up with the heater is doing any damage, there hasn't been any sign of it yet. I still have 100% confidence in the car and the drivetrain. Am I planning another road trip for next summer? 2,000 miles to the east coast (Canada) and back is on our radar.

[edwardb]

The heater control valve in a Mustang (and I would expect for the F150 Coyote as well) is a 4-way design that allows coolant to continue flowing with the heater core bypassed when the heat is off. Ford's instructions for the Coyote state that if a heater is not installed, it's still necessary to have coolant flowing from one side to the other. "If a heater circuit is not used then the heater supply must be connected to the heater return to allow air to be purged from the right hand cylinder head and provide sufficient coolant flow through the right hand cylinder head." Factory Five has added this to their later Coyote installation instructions as well. The heater control valve Factory Five supplies with their fairly recently released Gen 3 Coupe Heat/A-C system is also a full flow 4-way design. It's a little interesting Factory Five is providing a heater option without this kind of valve. Have you asked them about it? Your choice of course, but the cooling system design by Ford is expecting coolant flow at all times, for the reasons they cite.

A little more background: The Mustang performance guys have reported some issues with overheating cylinder #8 in the Coyote. This is apparently the hottest running of the cylinders, and the first to overheat if any issues or if the engine is pushed hard. Probably far beyond where most of us are pushing ours. But maybe another reason to make sure fluid is circulating as it's designed. This thread, while about the bypass mainly, does discuss a little more and has a coolant flow diagram if you haven't seen one: https://www.ffcars.com/forums/17-factory-five-roadsters/495114-coyote-heater-bypass.html. This article does a good job of explaining how the Coyote cooling system works. It's a little unconventional: https://www.diyford.com/ford-coyote-engine-cooling-system-performance-guide/.

[Fixit]

I'm muscling through this as well, and found this piece Heater Bypass Valve - Pull to Open (https://www.oldairproducts.com/product/25-1018-bypass-heater-valve-pull-to-open/Default.aspx?gfid=p123438&source=googleshopping&gclid=EAIaIQobChMI3uj3q8-j3QIVFcpkCh143g92EAkYBCABEgI4SvD_BwE) The photo doesn't show a 4th port/return... hmmm.

I'm going to take a look at the 4-way valve FFR suggests for the Coupe kit.

[1932]

You need to have water movement when heater is off. I like to bypass heater to keep heater out of cab- use a valve that keeps water moving but out of heater.

[Packer fan]

I installed a 4 way bypass valve.

Jim

[CVOBill]

98888Vintage makes an "H" pipe for the bypass. I used it in my Hot Rod.

[Alan_C]

I am using a 2nd Gen Coyote in my 70 Mach 1 restomod. I have been making diagrams for the cooling, AC, hydroboost, etc. In the upper right corner is the configuration I will be running for my heater core bypass. I ran the exact same setup on the 4.6L DOHC engine in put in my MK4, so I know it works. On the MK4, I found there was a output on the heater switch that was hot when any of the fan positions low, med, or high were selected. The heater switch output was used to energize the vacuum solenoid and let water flow through the heater core. The default was to bypass the heater core. Hope this helps, just one solution to consider.

https://i.imgur.com/R4UHj4gh.jpg

[bobm488]

I copied "Fixit" post 248. his instructions are very clear and goes in easy.

118889

[Ducky2009]

For the Coyote engine, Ford recommends that water circulate from head to head. With that being said, without a heater, run a heater hose from head to head but add a restrictor in the hose. If you're running a heater, add a 4-way valve, such as in the diagram in post #8. This allows water to circulate through the heater or bypass the heater and circulate from head to head.

[Badfish]

I'm planning to get the Electronic Bypass Heater Valve #50-1555 by Old Air Products, to bypass my Summit heater.