The new 5.0 V8 introduced in my (bought new) F150 has been losing antifreeze for well over a year. I finally found the culprit. It is a bad O ring in the plastic T connector (Part #DR3Z-8566-A replaces: BR3Z-8566-B).

Mine was leaking at the quick connect that leads to the thermostat housing. I wiggled each connection, and the one leading to the thermostat housing had a lot of play and antifreeze poured out. The O-ring (which is a "flat" o ring) inside had collapsed on one side.

The problem is that you can't buy that O ring from Ford. They charge you over $60 for the whole T connector. They have no part number, and the worst part, is that this T connector is in big demand. (It is also used on the newer Mustangs.) My Ford dealership said that the T connector is backed ordered 4-5 weeks, and they cannot get the O ring. They did get for me the other O-rings for the other connectors, but they are different. I confirmed with Ford home office that the O ring alone is not available.

But the part is available on E-Bay and some warehouses. No aftermarket yet.

If anyone finds a source for the flat O ring, let me know. My 2011 truck is down and out until I receive the part from a warehouse in OK.

Otherwise, love my truck. 75,000 plus miles in less than 2 years, 8 months.

Part number 23 in the diagram.

 

I searched ebay for both numbers and found tasca appears to have 4 of the old number. http://www.ebay.com/itm/BRAND-NEW-OEM-THERMOSTAT-HOUSING-T-CONNECTOR-2011-2013-FORD-F-150-MUSTANG-/360508527105?pt=Motors_Car_Truck_Parts_Accessories&hash=item53effb9201&vxp=mtr
I would call them and see if this is true.

 

can you measure the original part and find a cross reference:

http://www.mcmaster.com/#o-rings/=qlactr

Looks like levittown ford has them for sale(you need to work through to the cooling system section):

http://www.levittownfordsupercenter....p?cPath=30_210

Part # 10:

 

I'd just engineer it like tcp2 suggested. Measure it up and head to a hydraulics shop. Estimate the durometer based on comparing to other known o-rings at the shop, and you should be set! Easy peasy lemon squeezy.

 

Around here, a bearing/belt supplier usually sells o-rings. If you take the old one to one and tell them the application and chemical, they should be able to come up with a match. An automotive supplier should be able to do the same.

Take Care

Green Gem