I have a '99 3.0 4x4 and just replaced my camshaft synchronizer and sensor. While I was in there screwing around with that, I noticed this tiny line broken off. I'm not knowledgeable about engines in general. I'm learning as I go with this truck. I simply have no idea where to start in ordering the replacement part. I'm including a picture of it. Once I know what it is, I can find a new one and find instructions for changing it out.

 

Looks like the Heater flow shut off valve, it is used to shut off coolant flow thru the heater core when MAX AC is selected in the Cab

Should have a Grey plastic vacuum hose attached, hose runs from there to firewall and thru to heater control console

You can repair broken "hard lines" with regular vacuum hose.
Auto makers switched to hard lines because they are less expensive and make assembly easier at the factory.

Just cut a piece off the broken line and take it into auto parts store, get some rubber vacuum hose that fits snugly over the hard line, no need to clamp it, its a "vacuum" hose so "pulls" connections together, it won't "push" them apart.

Get more than you need, if one broke then others will as well, they are all about the same size

 

Ok, that makes sense. The repair issue is the gray line broke right where it goes into the plug, so there isn't any line to put a repair on. I might try to get the end out of the plug.

 

The line is just shoved in there, so it does come out, but not easily.

 

Yes, pull off the rubber elbow from the valve
Soak it in hot water and hard line will come out

Take that piece you cut off, or cut a piece off now, and put it in the rubber elbow, then use rubber vacuum line you bought to connect them together