"open system"

[kbusch18]

ok so i understand the change from open to close

 

i am just wondering from what basic model of jeep would you find the open system already factory installed or where would i fine parts out of a vehicle to make mine open

[mj Mike]

open system is the way to go. you are looking for a 1992 and up jeep cherokee 4.0l hi out put. get rid of that old presser bottle & get a over flow bottle. and 6 feet of 5/8 heater hose when u get the heater valve if u do. i do not run one or need one. this swap is worth wile and i am very happy with it .you will be to!

[Garvin]

I did this on my '90 XJ and it worked wonders.

 

If you're looking at doing it correctly, you will need a bunch of parts (listed below, all from a '92).

 

Radiator

Thermostat housing

Overflow bottle

Heater valve

Bunch of 5/8" hose (think I got 6' and it was more than enough)

 

You don't technically need the heater valve, just posting it if you were to convert it completely. You will also need to reroute your hoses (will need to take a glance under a '92+ to see the routing, I just went to the junkyard and took pics and wrote up notes on them). If you do not reroute your hoses, you will run into the same issue I had where the pressure will push coolant out of the overflow bottle.

[88pioneer]

All I used was the radiator, overflow, an heater valve. I didn't need the t stat housing

[terrawombat]

Yea, I don't see the need for the newer style thermostat housing, which just adds an additional threaded hole for a temperature sensor. I believe the Renix-era engines had this temperature sensor in the block.

[Garvin]

Yea, I don't see the need for the newer style thermostat housing, which just adds an additional threaded hole for a temperature sensor. I believe the Renix-era engines had this temperature sensor in the block.

 

When you replace the radiator, you remove the fan sensor in it (lower drivers side corner, towards the back of the radiator). The point of putting a new thermostat housing is now you're adding that sensor back in. It is also a two wire setup but you will need to splice lines in from the drivers side front corner to that sensor on the thermostat housing. When I put the sensor on, I ran to a junkyard to grab the correct pigtail and cut back as far as I can on that one. I ended up cutting after the connector (on the sensor side of the pigtail) of the RENIX style sensor and running from that, that way I'm not chopping up the main wiring harness.

 

The sensor that you are referring to on the back of the block is the temp sensor.

[terrawombat]

Ah, I forgot about that sensor on the radiator.

 

So, let me see if I have this straight. On a Renix-era vehicle, the temperature sensor on the radiator is to control the electric cooling fan (if equipped), the temperature sensor on the back of the cylinder head is for the instrument cluster gauge, and the temperature sensor on the block is for computer fuel adjustments.

[Geonovast]

Ah, I forgot about that sensor on the radiator.

 

So, let me see if I have this straight. On a Renix-era vehicle, the temperature sensor on the radiator is to control the electric cooling fan (if equipped), the temperature sensor on the back of the cylinder head is for the instrument cluster gauge, and the temperature sensor on the block is for computer fuel adjustments.

 

Correct.

[ParadiseMJ]

Ah, I forgot about that sensor on the radiator.

 

So, let me see if I have this straight. On a Renix-era vehicle, the temperature sensor on the radiator is to control the electric cooling fan (if equipped), the temperature sensor on the back of the cylinder head is for the instrument cluster gauge, and the temperature sensor on the block is for computer fuel adjustments.

 

Yes, that's all good, BUT, the sensor that you will get at the parts store is not a temp switch. It does not, and will not control the e-fan on/off. It is only a sensor to tell the computer (on 91+ models). If you want to put the switch into a 91+ t-stat housing you'll have to buy a special temp switch from a GM vehicle. It's only a switch and sends current to the e-fan control relay at a certain temp (~215-220) and turns it off when the temp goes down.

 

So what a RENIX has is:

a. a SWITCH in the radiator (for the e-fan control)

b. a SENDER, in the back of the head (for the gauge, light)

c. a SENSOR, in the block, under the manifold (for the computer)

 

I have done this mod on both my 88 4.0 and my 90 4.0, I did not replace the radiator switch for the fan, I just wired in a switch on my dash thru my e-fan control relay that I can flip on/off at will. If you want it to be automatic, you'll need to buy the right kind of switch for the fan control or it will not work.

 

 

Also, I deleted the heater control valve in both rigs but the XJ (90) is not affected by the coolant constantly going thru it, but on the MJ (88) it always blows hot. So, a heater control valve (the newer type) will go into the MJ

[HOrnbrod]

open system is the way to go. you are looking for a 1992 and up jeep cherokee 4.0l hi out put.

 

1991 and up XJ or MJ will work for this.

[mopwrd340]

my son picked up a raditor one day from pick a part it was brand new never had aything run through it . it was a open system one and i took my fan sesnsor out removed a plug on the new one and the sensor screwed right in . don't know what brand it was :banana:

[HOrnbrod]

A lot of replacement radiators work well for converting Renix cooling systems since they retain the fan switch bung hole. Even the aluminum single core radiator I use on my 91 has one.

 

[Suuperman]

Unless you really want or need to put in a new radiator with the filler neck on it you can do this conversion for under $50 and it requires no other sensor moving or anything. Plus when you need to replace your 'closed' radiator it's several $$ less than an open style rad.

 

You just need to get an inline filler neck from the summit catalog and then convert your bottle to an overflow OR get an actual oveflow bottle from a junkyard.

 

The neck will run you about $30.

 

Cut the upper hose about 3" or so off the radiator and put it in. You may have to cut (section) a little more of the hose out to get it all lined up right.

 

It works great. I have been running my '90 XJ like this for 6+ mos now (and we had 100* plus days here this summer) and my buddy did this on his daughter's XJ and his MJ many years ago. Both are still like this today and are working great..

 

I need to look at mine to remember which brand filler neck I used but I believe it has a 1.25" end on each side. it puts the filler at about the same height (maybe even slightly higher) than a '91+ filler would be so it's easy to fill etc. I can take pics if you like.

[sinkrun]

Pics would be great I am fighting with that plastic bottle right now and told myself I would never buy another. I would upgrade the whole system but my rads only a few years old so I do not want to buy another. I am ordering one tonight for the MJ.

[danbyrambler]

Superman - What PSI radiator cap are you using? I did the same thing to my MJ awhile back - 1.25 OD on both ends of the inline adapter from Summit & put the overflow bottle from an '88 Toyota 4x4 pickup by the MJs air filter housing - also put in a Prestone flushing tee - Never had any problems with the closed system, just wanted to make it easier to change the antifreeze - Thanks, RM

[Garvin]

When I did my conversion, I just bought a brand new overflow bottle for the open system. I believe I got it from Advance Auto for like $20 or $25.

[Suuperman]

I'm using a moroso water neck and cap. The cap says on it that it's a 12-16 lb cap but I believe the catalog rating was 15 psi.

 

And I was off in my 'measurement' on where it sits inline. It's actually about 10" from the radiator. This way it will clear the battery and the hood (so it doesn't hit when you close the hood).

 

If memory serves the neck was $29 and the cap was $9. Then the only other thing you need is an overflow bottle (or modify your closed system bottle to work as an overflow). Just make sure the filler neck you get has the overflow nipple on it

 

 

 

[terrawombat]

Thanks for those pictures. I did a quick search for in-line radiator water fill necks and found a few at Jegs and Summit. Advance Auto sells one, too, but it's plastic and I like the idea of it being aluminum. Only ones I have found are all 1.5" OD on both sides, so I'll have to double check the measurements to make sure that will fit. This seems like it would be a cheap way to get to an open system without having to remove the like-new radiator I just put in. Still need to grab a '91+ heater control valve...

[Suuperman]

I bypassed/deleted my heater control valve as well (it leaked). I notice no ill effects from it. My heat works fine and it doesn't make it hotter inside having the heater core always in the loop.

 

You can use the upper heater hose (t-stat housing to firewall) and then whatever size hose the bottom heater hose is from the water pump to the firewall.

 

it eliminates the rats nest and does away with multiple potential leaks. I know it is 'supposed' to be there but it hasn't hurt anything on mine. I did it to this XJ my '91 MJ (miss that truck) couple years ago with no ill effects there either.

[Suuperman]

http://www.summitracing.com/parts/MOR-63745/

 

Here ya go. The rad caps should be on the right side of this page.

[terrawombat]

Thanks for the link and, consequently, the part number for the thing. Found it on Amazon.com w/free shipping (as long as you have a Prime account, which I do).

[danbyrambler]

Superman - Thanks - I'm using a 18 lb stant-one with the P release lever - besides the easier anti freeze change thing I also wanted to limit the pressure in the closed systems bottle since stress cracks were the only problems I've ever had - was afraid the p bottle could/would be sucked dry if a 13 lb cap was used - RM

[sinkrun]

Just ordered mine, my plastic tank and that mess of hoses is coming out completely.

[Suuperman]

I bypassed/deleted my heater control valve as well (it leaked). I notice no ill effects from it. My heat works fine and it doesn't make it hotter inside having the heater core always in the loop.

 

You can use the upper heater hose (t-stat housing to firewall) and then whatever size hose the bottom heater hose is from the water pump to the firewall.

 

it eliminates the rats nest and does away with multiple potential leaks. I know it is 'supposed' to be there but it hasn't hurt anything on mine. I did it to this XJ my '91 MJ (miss that truck) couple years ago with no ill effects there either.

 

 

With my 'upper heater hose' comment I meant to put int here you use one from a ZJ. It is already 'molded' (bent) and is a fairly easy fit. You will have to cut some off of it as it is too long.

[terrawombat]

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.