On my radiators, old and new, ive got the two trans lines then a single

connection at the bottom of the radiators.

Anyone know what this single connection at the bottom of the radiator is?

Thanks.

 

Are you referring to the drain plug? or a 4th connection?

My replacement radiator I put on recently had 4 connections. The 2 outside ones were possible drain holes (1 was blocked the other had a spigot), The 2 inside ones were for the transmission.

 

It's the bung for the the drain spigot.

 

No, Its not the drain. On the bottom of the original and the new one are the same.
It has:

Drain plug

Lower radiator hose

2 transmission cooler lines

and one line that connects next to one of he trans cooler lines. It is rubber

then turns into a metal line and goes up into the engine somewhere.

When I disconnected it to install the new radiator a small amount of

Coolant came out, I connected it up to the new one the same. The new one

had a threaded plug for a connection there I had to remove the adapter

from the old one and reuse it.

Kinda stumped here what would one single line do coming off of the

radiator? Could this have something to do with the AC?

If you look at the pic in this link closely you can see, from left to right The drain plug, The unknown connection, The two trans lines, and the hose connection.


http://www.autozone.com/1/products/3...ium-c1329.html

 

I believe it goes to the throttle body

 

Possibly. I followed the metal tube up and it is heading that way, but what is

it for? To heat up the throttle body or something?

Thanks.

 

they keep the throttle body from freezing up in cold climates , thats what i read somewhere. there is a return line of the throttle body also ita a 1/2 rubber tube .

 

But there is only one line. Is this one a return and the antifreeze comes from somewhere else?

 

I haven't looked down on the radiator but one of my heater hoses between the water pump and the heater core has a tee in it with a smaller hose going off to the throttle body.. I think in addition to keeping it from icing up, it also helps heat the air.
My Lincoln TC also has this but I am not sure where both lines go or come from..
I do remember on the Lincoln that the fitting is steel pressed into aluminum and was almost corroded out.

 

That's the return line for the Throttle body heater, it goes up to the top of the TB, the input line is sourced off the intake under the TB

 

Ahhh, thats kinda what I was thinking but was not sure.

When I went to remove the adapter for that fitting it literally ripped fight off the radiator with almost no effort. I can see that the solder joint was in very bad condition. It could have started to leak anytime.


Thanks.

 

On my ‘95 4.9L 6 cyl, a 1/4” tube runs from the heater core return hose, 2+ inches over the coolant neck, then down the front left corner of the engine block, going nowhere near the throttle body. At the bottom, a rubber hose connects it to a standard 1/4"x3/8” MIP hose barb going into that extra line fitting in the radiator's lower tank. Except, it’s NOT a standard hose barb.

On the outside, it looks normal. Inside, however, is quite different. It appears as though someone drilled a pilot hole of 3/64” or 1/16”(can’t remember which after 6 1/2 years) through the fitting then forgot to drill out the rest of the bore. As such, obviously it is not meant to flow well in either direction, so it is unlikely meant to be used as or in a heating circuit.

I believe its purpose is to serve as a pressure relief bypass. We know that coolant expands; that’s why recovery tanks are connected to the radiator filler neck. But, when the engine is cold, the thermostat is closed, isolating the radiator from the coolant circuit (except thru the lower radiator hose, working against the water pump’s pressure flow). As the engine warms the coolant, it tries to expand in (what should be) a closed-loop system; since it can’t (or shouldn’t), the pressure rises. In turn, that pressure tries to equalize by expanding the softest parts of the system: the heater hoses, the hose connections, and /or the heater core. Unless there is a hose, say, connecting that part of the cooling system directly to the radiator through a restriction, allowing the excess pressure to bleed down steadily.

Also, it appears the thing is not entirely necessary. When I was replacing the radiator 6.5 years ago, I noted that the tube, apparently made of unprotected steel, was so severely corroded that it was weeping coolant droplets, so I decided to replace it. Unfortunately, none of my information sources and none of the auto parts people I spoke to, had any information that the part existed, much less what it is called, nor what it does. Which makes it “mission impossible” to replace. So I didn’t; I just removed it from the circuit. And my heater system has YET to explode!