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Hey all, Here is the model and information you need to know about my Jeep. 1989 Jeep Comanche Eliminator, 4.0L Straight 6, Automatic Transmission, 2x4, I have A/C and cruise control. I have managed to complete my closed to open cooling system conversion. I did not spend a lot of money and I also did not go the cheapest route. I shouldnt have to replace any more water pumps or worry about cooling ever again. Here is a list of components that I bought: //////////////////////////////////////////////////////////////////////////////////////////////////// 2-Row Radiator - $100 https://www.amazon.com/gp/product/B01EVWTXLY/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1 Quality: 8/10 Functionality: 10/10 Comes with elbow and straight radiator cooling line fittings. Radiator Cap - $35 https://www.amazon.com/gp/product/B01F93S3E2/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1 Quality: 9/10 Functionality: 7/10 It is very hard to turn on and off the radiator. 4' of 5/8" Black Heater Hose - ~$15 total Autoparts store 4' of 3/4" Black Heater Hose - ~$15 total Autoparts store (2) 5/8" to 3/4" Hose Adapters - ~$15 total Autoparts store One Gallon of Concentrate Coolant - $15 Autoparts store One Gallon of Distilled Water - $3 High Flow Thermostat Housing - $33 http://www.hesco.us/products/7882/cooling-system/133247/hi-flow-thermostat-housing-hfth2#.WRuBvWjyuwU High Flow 180deg Thermostat - $19 http://www.hesco.us/products/7969/thermostats-and-housings/43013/hp--gmfordamcjeep-thermostat-180-degree-4364#.WRuIYGjyuwU Thermostat Housing Spacer - $37 http://www.hesco.us/products/7969/thermostats-and-housings/43017/thermostat-housing-spacer-hesths#.WRuIiWjyuwU High Temp Blue Silicone Gasket Maker - $12 Autoparts Store Hi-Flow Water Pump w/ Gasket - $87 https://www.4wd.com/p/flowkooler-high-flow-water-pump-natural-1747/_/R-GNLS-1747 Hose Clamps - ~$10 Autoparts Store 6' of 5/16" Hose for Radiator Vent - ~$10 Autoparts Store (1) 5/16-18 by ~2" long (1) 5/16-18 by ~1-1/4" long *Not exactly sure on length because I gave up on using the housing spacer (I will explain later) *The housing spacer and thermostat housing comes with gaskets. Total: ~$396 Well worth it, will never have a cooling issue. Works like a charm. My Jeep is preventing global warming from happening. //////////////////////////////////////////////////////////////////////////////////////////////////// A few pictures of stuff I bought... Start taking off parts... I had to take off the supports on top of the radiator, loosen the belt, and accessory fan. See photo below. NOTE: See the square rubber supports on top of the radiator? You need to reuse those. Take them off and put them on the new radiator so you do not forget... :doh: At this point I drained the coolant and took off all the hoses and transmission cooling lines. There is no pressure in the transmission lines so no fluid should leak out! Here is my old radiator taken out of the truck. This also shows the fitting types for the transmission lines. See the bottom elbow transmission fitting? My new radiator came with a replacement. The stock one is one piece and not a swivel fitting like the new fittings. You MAY have to grind, file, sand, etc. the diameter of the new elbow fitting so the plastic quick disconnect fitting will slide on the new fitting. Either that or you can file the plastic piece like I did. See below. ^^ That plastic piece goes on the elbow fitting ^^ I found that there was two holes that did not line up to support the radiator...Both sides. So I zip tied them on. Not too important since there are other brackets supporting the radiator on the top. First issue I found with the housing spacer... The belt comes pretty close the to lower housing bolt. See below. Also you can see two brass inserts. That is a 1/4" plug on the right (wrapped in teflon tape) and 3/16" plug on the left. Normally sensors go there on the newer jeeps. The Renix older jeeps have the sensors elsewhere. Second issue because of stupidity (Halfway my fault). Hardware store worker said the housing bolts were M8-1.25. They are not... They are 5/16-18. So I stripped out the holes and the bolts. I said screw the spacer and used original bolts. Bad luck for trusting the hardware store kid. :fs1: A little fabrication was needed for the radiator cap on the support bracket. It comes pretty close. Also, the vent hose is a 5/16" hose. I re-purposed my coolant reservoir bottle for my overflow tank. I forgot to take a picture but the two heater hoses go straight into the heater core. This shouldn't affect the A/C as the heater valve is open when the A/C turns on. This info is straight from the Jeep service manual I have. Heat comes out of the vents when the blower fan isnt on which is the only case which could be bad... Heat could build up without the blower fan on and melt/overheat things in the HVAC. Other helpful things to note: Make sure to put fan belt shroud/cover on before the new radiator is in. Make sure to put the rubber supports from the old radiator onto the new radiator. !!!!!!!! LET THE SILICONE CURE BEFORE FILLING THE SYSTEM WITH COOLANT !!!!!!!! Feel free to message me for any questions about my experience with this upgrade. :cheers: :rock on: :clapping: :waving: . :MJ 2: .

Hello there, I have an 87’ mj 2.5L, having a serious problem with overheating. For the first two weeks i had it it was constantly overheating, then in one afternoon i put a new rad in, new thermostat, new filters, and an oil change. Immediately it solved the overheating issue. Been about a month now of smooth and perfect temp running, until it sat for a week then started overheating again. Before it was the radiator overheating, now it seems to be smoking out of the back of the engine block. I’m thinking it has something to do with the thermostat, if anyone has any ideas or solutions or want more information, please let me know!!! Thanks

I feel like my Jeep won't get up to temp. I posted elsewhere and was told it was nothing to be concerned about.. So per an IR thermometer at the t-stat housing, the coolant will get up to 170-175 degrees after 20-30 mins of mixed driving. -The heat works great and both heater hoses are hot. -The upper radiator hose gets warm-hot. -The radiator is reading 100-130 degrees via IR thermometer. The radiator cap does not get hot. It was 43 degrees out when I did this drive. 88 Comanche with open cooling system, 4.0l. Flushed the (already pretty clean and under 2yr old) cooling system 2 times, once with VC9 and the other dish detergent, with no heater core in the loop. Then replaced heater core, and put in a new 195 degree Stant thermostat. Coolant is roughly a 50-50 mix and all new. I did all this and now it won't get up to temp. Before this the Jeep always ran perfectly at 205/210 and never had an overheating issue. Any ideas?

DIY convert from closed to open cooling. This Write up is how I converted from closed to open cooling. You may choose other parts to achieve the same end result. I am converting because I am tired of messing with the pressure bottle, to remove the heater flow valve, and replace old hoses. Parts: Radiator with filler neck $82.57 * Part number: CU1193 Radiator cap $24.99 * (I bought a fancy cap with built in thermometer.) Part number: 2471S 2 Gallons antifreeze coolant $14.99 ea ($24.98 for 2) *** Item number: 7020022 10' 5/16 hose $19.90 *** $1.99 per foot Item number: 5194083 4' 3/4 heater hose $5.56 *** $1.39 per foot item number: 5192978 4' 5/8 heater hose $5.56 *** $1.39 per foot Item number: 5192951 Two 3/4 to 5/8 hose adaptors $2.99 ea ($5.98 for 2)*** Part number: 80424 A junkyard radiator bottle (I think mine was from a ZJ or WJ dad snagged it for me) Total conversion cost: $169.54 + S&H and tax Optional Parts: Later model thermostat housing with temperature switch new water pump Dual Fan Controller Second Electric fan for dual conversion Wire Relay or Fan Controller Power Switch MJ or XJ 2.5L Radiator Bottle $16.99 ** Part number: 52003213 MJ or XJ Bottle Cap $7.97 ** Part number: J3223202 Ordered from: Amazon.com * Morris4x4.com ** Advanced Auto Parts *** Tools: Gloves Safety glasses Knife or box cutter Phillips and flat head screwdrivers Bucket T-25 T-30 8mm Socket and or wrench 10mm Socket and or wrench Getting Started Start by draining out the old radiator fluid, removing the upper and lower radiator hoses, fan temperature switch, and if you have an auto transmission the transmission cooler lines from the radiator. Use an 8mm socket or wrench to remove the electric fan and clutch fan shroud. The radiator support is held on by several bolts 10mm and T-25 or T-30 (sorry mine where all stripped before I started not exactly sure the actual size). The bolts removed connect the support to the frame and front clip, then they are all out remove the radiator support. The radiator should come out without much fuss. With the radiator out of the way now would be the perfect time to convert to Dual electric fans and replace the water pump. Sadly I was running out of time due to fighting with stripped bolts so i was not able to do ether.... Depending on the radiator you get you may not need to change the thermostat housing. My thermostat housing is from a later model XJ, and can use a temperature switch. However the radiator I purchased has the hole for the fan temperature switch. Remove the 3/4 hose and the 5/8 hose from the thermostat housing and the water pump. Remove the old coolant pressure bottle and the hoses going to the heater core. Cutting the hose may be needed. The new hoses will need to be adapted from 3/4 to 5/8, the reason for this is the thermostat housing outlet is 3/4 connecting to the heater core that is 5/8, and the heater core outlet is 3/4 connecting to the water pump inlet that is 5/8. After all the old hoses are removed take your new 3/4 and 5/8 hose and route it however you like, then measure where to cut the hose in half. Use the 3/4 to 5/8 adapters as needed. Again the hose routing is: 3/4 from thermostat housing 3/4 to 5/8 adapter 5/8 to heater core inlet 3/4 from heater core outlet 3/4 to 5/8 adapter 5/8 to water pump The new coolant bottle is the next challenge. I ordered a 2.5L MJ/XJ coolant bottle that should fit on the drivers side fender, I will likely need to go back to a cone air filter to make room for it. Till I decide for sure what bottle I am sticking with I used one from a Junk yard Jeep and slightly modified it to work. I had to remove the old pressure bottle "shelf" to make room. I used a self tapping screw to attach the radiator bottle to the back of the engine bay where the old bottle was located. I routed the 5/16 hose around the back of the bottle and used the heater hoses as a bridge, ending where the radiator filler neck will be. Install the new radiator and reconnect the upper and lower radiator hoses. Reattach the radiator support. Connect the Coolant bottle hose to the filler neck. For good measure I zip tied all the new hoses in place. Fill the radiator system with 12 quarts (3 Gallons) of coolant. Must be a 50/50 mix, you can use pre-mix or concentrate with distilled water. you may not be able to fit all 12 quarts as there will likely be some coolant still in the engine. Bleed the air out of the system, Renix engines have a coolant temperature sensor on the back of the head accessible from the engine compartment. Clean up and all done Prior to this conversion My Jeep would boil over in 20 minuets and interstate travel was a no go. Now the temperature has yet to pass the 210 mark while traveling 75 mph on the interstate. A side note, my A/C seems to be blowing cooler as well now....

I have swapped a gm 4.3 into my 86 MJ. I used the Novak motor mounts and redrilled my factory transmission support/ crossmember. I have plenty of clearance at the front of the engine and I'm looking for advice on the radiator. The radiator had over 280,000 miles on it when the 2.8 finally went. I've already dropped in the 4.3, mated 700r4 and 231C from a gmc s15 jimmy. Will the stock style 2.8 radiator cool the 4.3 or will I need to upgrade? If I change to the 87 up radiator, will I have to change my hood latch/ front end? Thanks for the help!

Hey guys I am New here i am now the proud owner of a 1990 4.0l renix thanks to the other forums regarding this, I am 95% complete. I am in the process of swapping out my idiot gauges for a full panel, i have only one issue so far and that is the part number for coolant temperature sending unit. I bought one from autozone its part number is tu108, however i do not know if that is for an idiot switch or for the temperature gauge, if someone has a part number it would be awesome. thanks Dis i have almost every major auto part store near by i prefer, oreillys or autozone(only bc they had it in stock)

i'd like to know if anybody would like to get a list together (or knows of one) of different types of hood vents that would work well on an mj or an xj. i know of the lebaron ones, but i've heard of people using others. anything we should be on the look-out for?

Hi all. Todays project for me is to wire my aux fan up so that when the truck is running, the fan is running. When my engine was replaced, the fan was never put back in. I installed it, but can't find the original wires for it. The truck likes to heat up in traffic, so I feel better with it running all the time. It's an 88 Pioneer 4.0L Is there a good source of power under the hood, or do I need to go under the dash with it? I'm alligator clipping it on to the battery now. Thanks in advance. Once I get this one done, I think I'm on to the hard projects.