Replacing heater hoses

[jodawill]

I'm trying to track down all of the heater hoses for the original configuration. The hoses I'm finding online just don't seem to be correct.

 

Rock Auto (and everywhere else) lists this 9/16" to 5/8" hose. But my measurements put it at 5/8" on the tee and 3/4" on the engine. Should I buy these and stretch them to fit? There's this 5/8" to 3/4" elbow, but the original has two angles.

 

Here's my understanding of what I need:

 

The heater valve has three 5/8" connections:

1. Goes to the 1/2" connection on the side of the reservoir - straight 5/8" to 1/2" hose - FOUND
2. Goes to the 5/8" connection on the heater core - straight 5/8" hose - FOUND (common hose)
3. Goes to the 3/4" connection on the water pump - 5/8" to 3/4" double elbow

 

The tee also has three 5/8" connections:

1. Goes to the 7/8" connection on the bottom of the reservoir - maybe stretch the 5/8" to 3/4" elbow?
2. Goes to the 3/4" connection on the heater block - maybe just stretch the 5/8"?
3. Goes to the 3/4" connection on the thermostat housing - 5/8" to 3/4" double elbow

 

Could someone shed some light on this?

 

Thanks!

[jodawill]

According to Rock Auto, this is what I need for the heater valve assembly. This appears to be correct. I think I was wrong about that long one being a double elbow.

 

I still have an issue though because the double elbow one that connects the tee to the water pump says 5/8" to 9/16", which is not what I measured. It should be 5/8" to 3/4". Perhaps this is a data entry error?

[jodawill]

The specs for this hose is contradictory: https://www.rockauto.com/en/moreinfo.php?pk=1332841&cc=1181720&pt=6892&jsn=3243

[JZLAJeep]

I take it you are keeping the closed system and keeping the two factory "Ys" and connecting into them? Before buying any specialty hose, I'd just buy 3/4" and 5/8" hose from the auto parts store make connections where you have to. The hose will bend and loop some without kinking. Or, this will be a good time to convert your system to an open system and get rid of the heater control valve which simplifies the hoses. There is a lot of information out there on the topic, including the link that keeps the old radiator.

 

I recently made the closed to open conversion with a new radiator and overflow bottle and simplified the hoses to the firewall so there is one 3/4" hose and one 5/8" hose, just like Jeep did in and after 1997.

 

[jodawill]

On 7/10/2026 at 10:10 AM, JZLAJeep said:

I take it you are keeping the closed system and keeping the two factory "Ys" and connecting into them? Before buying any specialty hose, I'd just buy 3/4" and 5/8" hose from the auto parts store make connections where you have to. The hose will bend and loop some without kinking. Or, this will be a good time to convert your system to an open system and get rid of the heater control valve which simplifies the hoses. There is a lot of information out there on the topic, including the link that keeps the old radiator.

 

I recently made the closed to open conversion with a new radiator and overflow bottle and simplified the hoses to the firewall so there is one 3/4" hose and one 5/8" hose, just like Jeep did in and after 1997.

 

I tried using regular hoses first. The problem is that out of all six of the hoses, only one of them is actually the same size on both ends. I tried going the route of using tees and adapters, but it turned into an unmanageable mess. I suppose that's the route I'll have to take if the hoses from Rock Auto don't work. I'm assuming that the specs on that double elbow hose are wrong. Hopefully it all works out.