I found the leaking part and now I know why it didn't show up in any parts diagrams lol. It is a heater bypass cap. We bought the car when we still lived in Florida so a previous owner must have bypassed the rear heater or something. Should be an easy fix and hopefully I'll get another 130k miles before it gives me problems again!

 

Yeah, normally there is a hose and pipe assembly back there that's returning coolant from somewhere... though I'm not immediately familiar with where it ultimately goes!

They certainly seem to have bypassed something...

 

Yep, does appear to be the heater core return hose/pipe assembly that has been disconnected/removed and capped off...

Normally a short hose there going over to a pipe bolted to the back side of the motor with that pipe ultimately heading upward behind the driver side of the motor where there is another short hose that, presumalby, attached to heater core return piping. I say "presumably" because I've never actually paid any close attention to where it connects on the upper end!

Suspect you have another cap up there somewhere...

 

The strange thing is that the heater works fantastic in the van and it does have the normal heater tubes going into the firewall. Just wondering if this is maybe a normal condition for vans with the dual HVAC system. Thankfully I got it fixed and we'll see how long it lasts. The part was $3 so I guess that's better than a blown head gasket lol

 

This thread shows the pipe assembly and a service manual drawing regarding it's location/routing.

https://www.chryslerminivan.net/threads/weeping-heater-hose-pipe.170687/

 

This thread explains it....in that diagram, look at item 1. It says Cap & Clamp and that is what I have, so I must have the oil cooled version. Thanks a lot. I wonder if I would be able to find the actual Mopar parts for Cap & Clamp?

 

Yep, found the Mopar part numbers - Cap - 55055694AB (Discontinued) & Clamp - 6502017

Hopefully my Dorman replacement cap will hold up.

 

Ah, good catch on that drawing! So you've probably got the "Tow Package" on that van... as I think that was the package that added the oil cooler.

None of my T&C Limited vans have the tow package so I've only ever seen the hose & pipe back there!

 

It did come with the tow package! I just road tested it and the cap is holding for now. I reused the old clamp, so that probably wasn't the best decision, but we'll see how it goes.

 

The clamp is most likely fine if it felt tight going on. They don't really wear out. Another fix would be to get a small piece of fuel line that size, clamp it on, stick a bolt tightly into the open end and clamp that with a screw clamp. I've done that many times over the years for various issues and never had a problem. I would trust that more than a cap.

 

Good advice! Thank you. If it gives me any more trouble, I will try this. The clamp did feel tight going on, but I didn't like that I could spin the new cap with my hand after putting the clamp on. I might swap out the pinch clamp with a screw type host clamp so I can tighten it more. I'm hesitant to mess with it though because if the cap comes off when I am removing the clamp, I will be taking another bath in coolant.

 

Yeah, that's not very confidence inspiring. I prefer screw clamps for most applications. Some people say spring clamps are better because they expand and contract but I like be in control of how tight they are. Most problems from screw clamps are because people over torque them and cut into the hose.

If I were to swap the clamp I would put my finger on the end of the cap and slide the clamp as far off as I can. Then pinch the hose from the bottom, where the clamp was, and slide it off the rest of the way.

 

For your application, these are junk, worm gear screw clamps.

Ideally you want some like this as you want control.
The t-screw holds better with equal force all around vs worm gear tight on one side only by the screw.

This is what you will see on performance vehicles too.

 

If you leave the radiator cap on and clamp off the overflow hose you may get lucky and not get quite so wet.

 

Overflow hose?

 

He's referring to the hose going from the radiator neck, just under the radiator cap, over to the coolant overflow reservoir at the front driver's side.

In other words, he's saying that if you keep the system closed up everywhere other than the cap you are going to replace then the lack of venting will assist in minimizing how quickly coolant flows out that return nipple you are working on as there will be somewhat of a vacuum fighting the flow.

Of course, this assumes that your radiator cap itself is good and sealing properly... and that there are no other leaks elsewhere in the system!

 

Will report back how this goes lol

 

You could pull the cap and catch the coolant in a clean container. Add it back to the radiator when you're done. Or just drain the radiator again and reuse the fluid.

 

I like the general idea, but the location guarantees that the coolant that comes out will not be reusable. It will definitely hit the frame on it's way down. I'm just going to try and swap the cap as quick as possible to minimize the amount of lost coolant.

 

Any dirty old container or even a stout cardboard box... the trick to clean and reusable fluid is a clean new trash bag.

Another trick for working on fluid with our hands is to tie a rag around your wrist to stop the fluid from running along your arm and into your armpit, beyond

 

Yup. Could probably buy a couple cheap wrist sweat bands on Amazon.

A funnel attached to a hose to direct it to a container works too.