I am prepping for a cooling system service. Thermostat. coolant and hoses. I see that there is a tee in the right bank to the heater core and radiator. What size or diameter heater hose do I need to order? Any recommendations for the tee? I'm pretty sure mine is the original ford, tee is crimped into hoses. I am just trying to get everything lined up before draining the system.

Thank you

 

5/8" heater hose like every other Ford I've seen. Not sure about the T, my IDI had no T when I got it. Just direct to heater core and out to water pump, which I have put a coolant filter inline before the heater core. Interesting note is the IDI NPT to 5/8 nipple on the passenger side head has a restrictor inside, a square cut washer reducing diameter that coolant can flow. There are usually brittle or disintegrated and no idea on size as I've never seen one removed and intact.

 

Thanks for the info. Mine goes off the passenger side head to a tee which goes to heater core and all the way down to the lower radiator. The tee is crimped to the hose so I assume its original.

 

This is a long post discussing this special fitting and it's function for E4OD transmissions plus a possible optional use for trucks with other automatic transmissions.

The cooling system for trucks with the E4OD is designed that way so it's probably original.

The fitting on the lower tank of the radiator is 1/2 inch and it takes a 1/2 inch (Inside Diameter) heater hose.

Although the fitting takes a 1/2 inch hose, the passageway through that fitting into the lower radiator tank is very very small. Somewhere close to 1/32nd to 1/16th of an inch, (probably 1.0mm to 1.5mm) judging by the photo. Here is a photo of the radiator fitting that I posted in a different topic in Oct. 2015. This is from a very good quality after-market Brass/Copper radiator that was in a 1991 F350 parts truck with an E4OD.
The hole is counter-sunk (bevelled edge) so it's a bit smaller than than the initial opening.



1/2 inch Coolant Hose Radiator Fitting on Right for an E4OD transmission




It's purpose: After start-up the coolant inside the engine circulates mostly inside the engine, into the heater core and back to the water pump through the return hose from the heater core. The coolant does not go back into the radiator until it gets warm enough to open the thermostat (except a very small amount through bypass valve in the thermostat housing). During this 'warm-up' time the coolant in the radiator stays cold until the thermostat opens to allow the hot coolant circulating inside the engine to flow into the top radiator tank, and down through the tubes to be cooled. There is a heat exchanger inside the bottom tank (aka: transmission cooler) that looks like a big brass tube. It has some kind of fins or channels on the inside to conduct heat from the transmission fluid. Transmission fluid is pumped through that heat exchanger where under normal operating conditions heat is conducted from the transmission fluid and picked up by the circulating coolant to keep the temperature of the transmission fluid in the normal operating temperature range.

Slightly off topic but I want to point out here: Contrary to some opinions that I've read in other related topics, these automatic transmission heat exchangers are very efficient, much more efficient than external auxiliary transmission coolers that remove heat by airflow over tubes and fins or plates and fins. It's NOT a good idea to bypass the transmission fluid heat exchanger in the radiator and use only an auxiliary transmission cooler. (which is sometimes done when the exchanger begins to leak inside the radiator) Unless you have no alternatives at the time- such as "can't afford a new radiator" and you need the truck NOW). Two reasons: The aux. cooler depends upon adequate air flow and is not efficient at low engine RPM in stop and go traffic = transmission is more likely to overheat. Also, with the E4OD there would be no way to help preheat the transmission fluid through the heat exchanger during engine warm up which is the PURPOSE of the hose and fitting we are talking about.

With your E4OD transmission there is another very important function of this heat exchanger and THAT is what this additional hose is for.
That function is to ADD HEAT to the transmission fluid through the heat exchanger during the warm up period (before the thermostat has opened) to help bring the E4OD transmission up to it's normal and safe operating temperature range more quickly after start up.

Keep in mind that the coolant in the bottom tank (and in the radiator) is cold* until the thermostat opens and hot coolant begins to circulate in the radiator. Therefore, as the transmission fluid is pumped through the heat exchanger before the thermostat has opened, much of that heat is removed from the transmission fluid and it would take a longer period of time for the transmission to finally come up to it's safe and normal operating temperature range.

*Also NOTE: during normal operation and driving, the engine temperature (coolant temperature) shown on your temperature gauge is sensed from location in the engine where flowing coolant temperatures are going to be near their highest temperature. The temperature of the coolant in the bottom radiator tank, after it has flowed down through the cooling tubes in the radiator is very much cooler! People seem to often overlook this fact when they are considering how the transmission fluid heat exchanger in the lower tank works and how efficient it is. It is MUCH COOLER than the temperatures shown on the temperature gauge and it is very efficient in removing heat from the transmission fluid.

This extra 1/2 inch coolant hose diverts some of the hottest coolant circulating in the engine during warm up, directly to the lower radiator tank and heat exchanger which reduces the amount of heat removed from the transmission fluid. In effect, this ADDS HEAT to the transmission fluid to help bring the E4OD transmission up to it's safe and normal operating temperature range much sooner. Apparently the engineers at Ford, and/or whoever designed and manufactured the E4OD saw the necessity for this.

Another important thing to NOTE: The passageway through this extra hose fitting on the radiator is very small! The reason for this is, we DON'T want to divert too much coolant from the heater core hoses because normally ALL of that coolant flows directly back to the water pump. If the amount of coolant going back to the water pump is reduced too much OR if that flow is otherwise restricted then it has been my perception that this is likely to cause the water pump impeller to pull a vaccum void (air space) in the area near the coolant entry point of the return hose back into the water pump and cause water pump cavitation, especially at higher RPM and resultant cavitation damage that could cause the water pump to fail prematurely.

Off Topic but: THAT is the reason why I have cautioned AGAINST installing a coolant filter directly in-line in in either of the heater core hoses (most often it's installed in the return line back to the water pump). As the coolant filter becomes plugged and the coolant flow back to the water pump becomes restricted, cavitation is likely to result - that's my perspective. Thus, it is best to install a coolant filter directly across the two heater core hoses in a parallel fashion rather than 'in series' in one hose. The difference in pressure between the two hoses (one going into the heater core and the other one coming out and back to the water pump) will provide enough flow through the coolant filter for it to be effective and with no possibility of obstructing the flow back to the water pump.

Back to this additional coolant hose for E4OD transmissions: I do not know if this design feature was continued for the 4R100 transmissions and I would really like to know that. If not, it might indicate a recognized weakness in the earlier E4ODs and this feature was added to remedy that weakness OR if it's continued with the 4R100 series then it may just be an essential design element for these transmissions. Does anyone reading this know?

I think this feature is very interesting and would probably benefit a C6 transmission to help bring transmission temperatures up to safe operating range more quickly. ESPECIALLY if you are using a larger axillary transmission cooler, larger than the original ones provided in trucks that were equipped with a tow package.

I recently installed a radiator designed for the E4OD (with this extra fitting) in my 1987 6.9L with the C6 transmission and I am planning to use that fitting for a return line from a coolant filter installation which will be in a single hose coming off of a 'Tee' fitting in one of the two heater hoses. I haven't decided which hose yet. There would be some small differences with each option and I'll make that decision when I determine what climate zone I'll be living in next year.





I would like to know exactly

 

Thanks for the input Fixnstuff. That pretty much means that the tee I picked up at Napa today isn't going to work then..lol Now I need another 5/8 to 1/2 tee and some 1/2 inch heater hose.

 

Where can I get this special fitting? Im trying to replace my radiator and the fitting is rusted on something fierce. Ive googled it every way imagineable but can't seem to find new or old parts for this.

 

Have you tried using some heat yet? I would put a torch just outside the fitting on the radiator. She should break free.

 

I know this is an old post, but does anyone have an idea where to source these hoses with the integrated "Tee" in it? Or is the answer either a junk yard or /I just to get hose fittings and make it?

 

I got a tee off amazon. Four Seasons 84543 heater hose fitting 5/8 x 5/8 x 1/2. It's 1/2 hose to the lower radiator tank.

 

Awesome! Thank you!

 

You're welcome.

 

The fitting is not rusted on, IT'S BRAZED to the internal brass heat exchanger and to the lower radiator tank during the manufacture of the radiator so won't be able to remove it.
This fitting is pre-installed (TIG welded) on aluminum radiators for E4OD transmissions and you need the correct IDI diesel radiator for a truck or van with an E4OD.