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Superman - Thanks for the tips. I got the inline radiator fill neck in the mail today. I'm going to hit the junkyard on Saturday for some things for my '92MJ and I'll see if I can grab an upper heater hose off of one of the ZJs they have in the yard. If not, I can just get some cut to length at the auto parts store for cheap. As long as you say the heater still works without the valve, that's good enough for me...the truck I'm trying to do this on has been demoted back to a full time work-truck for the time being (or until the motor finally pops because of it's ridiculously low oil pressure) so I'm not too concerned if it pumps out scorching heat, especially not with the cold weather rolling in. If I can find a '91+ heater valve at the yard in good shape, I may just grab that and the hoses, though. Thanks again.

 

You can also use the molded hoses (w/o the water control valve) from a 97+ XJ as they stopped using the valve in 1997. I ditched the valve years ago. Just another useless part that breaks and cause problems.

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Superman - Thanks for the tips. I got the inline radiator fill neck in the mail today. I'm going to hit the junkyard on Saturday for some things for my '92MJ and I'll see if I can grab an upper heater hose off of one of the ZJs they have in the yard. If not, I can just get some cut to length at the auto parts store for cheap. As long as you say the heater still works without the valve, that's good enough for me...the truck I'm trying to do this on has been demoted back to a full time work-truck for the time being (or until the motor finally pops because of it's ridiculously low oil pressure) so I'm not too concerned if it pumps out scorching heat, especially not with the cold weather rolling in. If I can find a '91+ heater valve at the yard in good shape, I may just grab that and the hoses, though. Thanks again.

 

You can also use the molded hoses (w/o the water control valve) from a 97+ XJ as they stopped using the valve in 1997. I ditched the valve years ago. Just another useless part that breaks and cause problems.

 

Thanks for the tip! Tonight, I started on converting the truck into an open system. Removed the expansion bottle, heater control valve, and all heater hoses. Cut the upper radiator hose and spliced in the Moroso radiator fill neck. Stuck it right on the factory "ledge" attached to the A/C compressor that normally holds the radiator hose - worked out pretty nice.

 

Now - onto the heater lines. I have a spare set of 97+ XJ lines from an engine I picked up at the JY. The bigger, heater inlet hose from the 97+ XJ fits just fine, but the outlet hose is a little bit short and I found out why. On my '88MJ, the metal tube that comes off of the water pump is much shorter and just sticks straight up. On my '92MJ, '98XJ, and '01XJ, that same metal tube comes straight up and then makes a 90 degree bend towards the rear of the engine, thus requiring a shorter rubber hose to the firewall.

 

So, I'll use the 97+ XJ inlet hose, but will have to get a cut length of 5/8" outlet hose for the other side - no big deal. The finale to this project will just have to wait until tomorrow.

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I just did mine today and its working great nice clean install. I was wondering if the overflow is needed or what would happen without it as I seen to remember the olders cars not having them just the hose running down a corner of a fender. Mine did push a little out maybe it was just a little full.

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The overflow / coolant recovery bottle is a very good idea -Super easy way to keep an eye on what's going on - as the coolant gets hot it expands - if the pressure caused by this expansion exceeds the pressure caps rating then coolant will be forced past the cap & into the bottle - The reverse happens when the engine cools - the decreasing volume coolant now creats a vacuum & the bottle returns liquid to the system - when the cooling system is opened for a new hose-new thermostat-af change or whatever some air will be introduced & is usually purged 1st before any liquid may be forced out & the resulting vacuum will again draw from the bottle; then additional coolant needs to be added to the recovery bottle & monitored until the system stabilizes - 2 or 3 normal operating temp to cold engine cycles usually - Then life is good & on automatic until maybe one day you notice the bottle's level a little lower & when refilled it keeps on getting lower - Then you start the hunt for just where the coolant is disappearing to.

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Thanks for all of the tips in this thread. Went to the auto parts store, picked up some hose, flush kit (just in case) and some clamps. Also got a universal coolant overflow bottle w/metal basket, hardware and hose for $10. Installed everything and took the truck through it's normal "test" route around town, in a neighborhood, and on some 50MPH roads. Temperature held pretty steady right below 210*F. Would rise a bit when I came to a stop sign or traffic light, but nothing too drastic. Looks like my overheating problem may be fixed. I think I need to add some coolant as I got nothing out of the overflow line, but I'm out of anti-freeze. I think once I get the system completely filled and burped, it'll stay under 210*F when I'm stopped and idling. Now, onto the oil pressure problem...

 

Here are some pictures of the setup:

 

 

 

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  • 8 months later...

I'm tooling up to set up my 'open cooling system' this week.

 

Just about to start ordering parts and got a couple question. . . . . . .

 

Pros/cons of having the rad with a filler neck or one without?

 

And

 

Why do I need a new heater flow control valve? :dunno:

 

image_209027.gif

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I'm tooling up to set up my 'open cooling system' this week.

 

Just about to start ordering parts and got a couple question. . . . . . .

 

Pros/cons of having the rad with a filler neck or one without?

 

And

 

Why do I need a new heater flow control valve? :dunno:

 

image_209027.gif

 

Having a rad with filler neck is nice since it makes the system look factory and like it was done properly, however, it will be more expensive to get a brand new radiator with filler neck versus getting a brand new remotely mounted filler neck that is spliced into your upper rad hose.

 

I completely eliminated my heater flow control valve and have yet to see any adverse effects from it. Someone said that without it, my heater core would always have full flow going to it (which I don't disagree with) and that it would affect my A/C during the summer (by making it not as cold). I have yet to experience that. Even on the 100+ degree days we have had my A/C has been pumping out nice, cold air.

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Why do I need a new heater flow control valve? :dunno:

 

image_209027.gif

Bump :brows: Anyone got some input about this?

As far as I can see the heater valve on my truck is an inline type so if I just replace the heater hoses from the block to the heater core with generic heater hosing which gets rid of the all the T junctions and then put the valve back inline that should work fine shouldn't it? Or is there something I'm not aware of about the valves? :dunno:

I have no A/C so being able to have a bit of cool air on my feet in the heat of summer is essential! I can't do that if I remove the valve completely from the system.

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Not 100% sure of this but i don't think not having the heater control valve will make your vent air any hotter. The way i see it is there are seperate departments in the heater,evap,blower motor assembly right? I mean if when you change the coolness setting at the dash it doesn't limit the amount of hot water let through the valve it just opens it when any heat is disired right? Seems like the heater control valve is just a vacumme controled water switch or sorts, on or off. So if you have your comfort switch set to cool then i imagine the trap doors in the whole assembly will just pull vented air from somewhere that is not the heater core...thus cool or as cool as outside air blowing. I will have to look at my controls again to make sure i stated this correctly but i also have put a 96 radiator and eliminated the control valve in my 88. so far it has been the best upgrade i have done.

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