Redo coolant plumbing? (RENIX)

Many of my hoses are shot on the passenger side of the engine. I want to replace the hoses that come out of the thermostat housing and run to the pressure bottle and heater core. These are pre-built with metal fittings for tee's (rusted out big time). Is there any reason why I can't just make my own setup using new hose and tee's and not go looking for the pre-fabbed hoses? I mapped them out and it looks like 2 very similar t-split assemblies. I would preferably use copper or galvanized tee-junctures, but have only been able to find nylon. Anything wrong with nylon or copper for the application? Are these under too much pressure for a normal hose connection with clamp to deal with?

Thanks for any tips..

Pressure would be no prolema--only about 16 or so psi present. Temperature would be a concern--but it would only have to stand up to about 260 degrees, worst case. How would coolant effect the material?

Anyway, 5-90 and a lot of others have rolled-their-own out of copper/brass. There is one(?) hose that is special--stepped from 3/4 to 5/8 or something like that. You can get a brass barbed adapter to take care of that.

Are you considering elimination of the coolant control valve? Many others have done it, its on my "Jeep-Do" list.

you dont need no stinkin' 3/4 to 5/8th's hose. and just forget the heater control valve, route stuff directly.


no need for copper pipe, unless your talking about the waterpump peepee.

Yah - cranked up a set of copper tube plumbing using 1/2" tube in about a half-hour, once I got tired of buying moulded right-angle hoses.

There are two spots where using 5/8" hose (1/2" copper line) won't work - at the thermostat housing and the bottom of the plastic volume tank. Both spots take 3/4" hose.

Easy enough - at those spots, instead of leaving the 1/2" tube bare (to fit in the 5/8" hose,) put a 1/2" straight union on the hose - making it ~3/4" ID and the 3/4" hoes will fit neatly.

Couple the plumbing assembly to the engine and firewall with short bits of rubber hose - "vibration stubs."

I've attached a pic of my "quick and dirty" job - I do need to refine a few things. The valve is a "force backflush" valve, and the blind fitting is a hose bibb adapter. Connect the garden hose to it, close the valve, and you have a reverse flush under mains pressure. Remove the hose, replace the cap, open the valve and drains, and drain out the tap water. Close the drains and refill. The hose bibb can also be used as a fill port to backfill the system compleatly (RENIX) and cut down on air pockets in the system, in addition to drilling the thermostat flange to pass air bubbles out and coolant in to displace the air.

Yes, I also replaced the nipple coming out of the water pump with a run of brass and an elbow - I didn't like having a rubber hose behind the idler pully, no matter how secure it's supposed to be. The port in the water pump is threaded 3/8" NPT, so use 3/8" pipe (which is also right about 5/8" OD, and readily accepts a 5/8" ID hose.)

5-90 is the man when it comes to that.
Consider the shape of the rest of the cooling system as well.

I recently swapped my MJ over to the HO cooling system, and not dealing with the pressure bottle happens to be awesome. If your radiator is in bad shape anyway, it may be worth doing.
the HO heater core valve is $25.

5-90 said:

Easy enough - at those spots, instead of leaving the 1/2" tube bare (to fit in the 5/8" hose,) put a 1/2" straight union on the hose - making it ~3/4" ID and the 3/4" hoes will fit neatly.

Click to expand...

Do you mean a 1/2" copper coupling?


This is a union, which is used to connect two pieces of pipe when you can't turn either one.

kujito said:

Click to expand...

Well, I learned it as a "union" being a "straight connection" - of whatever sort.

Anyhow, ya got me - and the pix will help everyone else!:roflmao:

I just had a picture of some guy in his driveway, cooling system apart with no other way to get back to the hardware store; staring at the union (in pieces) like "How the fawk is this supposed to work?!"

Thinking about it though, it would give you the ability to open it up without messing with the hose clamps on your "vibration stubs." The end on the right in the pic, is ~ the same O.D. as the coupling.

5-90 said:

Well, I learned it as a "union" being a "straight connection" - of whatever sort.

Anyhow, ya got me - and the pix will help everyone else!:roflmao:

Click to expand...

I sense a great disturbance in the Force!

thats funny, ive done 3 radiator remove/replace's in the last 2 months, and have not used a single INCH of 3/4 hose... its all 5/8ths for me... granted i dont have any overflow pressure bottles.... but 5/8ths WILL go on the t-stat housing...

Just did my 87, it was all 5/8ths