Heater hose sizes for 87 MJ

[Top C]

I am going to do away with the vacuum heater valve and run hoses directly from the thermostat and pump directly to the heater core. I'm also doing away with plastic water bottle  and put the inline radiator filler and cap adapter in upper radiator hose. So I've have a simple question what is the heater hose sizes for the upper and lower heater pipes and what is the size at the other end of those hoses that go to the  water pump and thermostat ports?  I wanted to get everything together before ripping the current system apart.  I've look in many places but I guess I haven't looked  for the sizes in right place.  One place I looked said they used a 97 Cherokee heater hoses as a direct fit, has anyone used this approach yet?

 

Thanks for your help in advance

Mike

[Fernando87mj]

Yes the 97 hoses have been used before. I plan on doing the same once I swap to the open cooling system. Check this thread out , it has some good info 

 

[coolwind57]

i remembered that there was a funky issue with using 97+ heater hoses on our Renix MJs, but I couldn't remember exactly what it was.  I had to go look up my notes, which  I posted under my build thread.  Here's what I did for my conversion last year:

 

I converted from closed to open system.  I did the upper hose pressure cap technique, retaining my Renix-era radiator.  I used a later model XJ reservoir and found that I was able to fit it pretty well back on the firewall, facing opposite of what others had facing.  My old pressure bottle mount was modified and with a little welding, it all fits securely.  Painted white because that's all I had at the time.  I'll probably go over it with some black paint later on.  

 

Man, it sure cleared up a lot of space around my oil filter.  Simplifies the heater hoses and overall cooling system now so that even I can understand and more easily troubleshoot.  

 

I used the curved ends nearest the heater core of the 97+ heater hoses that I acquired from the junkyard.  Also fitted in a Prestone backflush port.  

 

Heads up if you don't already know:  The 97+ heater hoses will fit perfectly--if you want reverse flow into you heater core, which you DO NOT WANT.   In 97, Jeep cleaned up all the mess and complication of the heater control valve mess, but in doing so, they also reversed the outside diameters of the two heater core pipes.  So in other words, the front of the 97+ heater hoses plug in to the water pump and thermostat neck of the Renix era engines perfectly.  The rear ends of the hoses are now opposite IDs of what they should be to fit Renix.  A bit of a disappointment I suppose as I had plumb in 3/4" to 5/8" reducers for both hoses.