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Heater Control Valve

Old Dec 28, 2011 | 03:53 PM
  #1  
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From: shelley, idaho
Year: 1988
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Engine: 242CID I-6
Default Heater Control Valve

do i need it? mine broke. can i bypass it ? anyone done it?
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Old Dec 28, 2011 | 04:21 PM
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From: MI 48642
Year: 1996
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I bypassed mine a few weeks ago. Much cleaner in there, and no more leaking! Just run hose strait from the tstat and pump to the top and bottom of the heater core. Flush the core out while you have everything apart also. I forgot how the flow goes so if you cant find that, ill run out and check for you.

Make sure to plug that vacuum line going into the top of the valve. An old screw, golf tee, anything really. I tucked mine down under the washer fluid.
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Old Dec 28, 2011 | 04:28 PM
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you still running the factory bottle
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Old Dec 28, 2011 | 05:33 PM
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Sure you can bypass it. Later year XJs don't have it. It was a crappy under-designed piece of hardware anyways...
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Old Dec 28, 2011 | 06:35 PM
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When mine goes out again... (already did once) I plan on by-passing it.
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Old Dec 28, 2011 | 06:51 PM
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stock bottle, the guy at the local jeep store says it will make your heat stay on all the time. i cant see how that would be true but? here in southeast idaho it goes from -20 to 100 so..........
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Old Dec 28, 2011 | 06:57 PM
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Originally Posted by jhampton
stock bottle, the guy at the local jeep store says it will make your heat stay on all the time. i cant see how that would be true but? here in southeast idaho it goes from -20 to 100 so..........
Your heat wont stay on all the time, you will just have coolant flowing through the core at all times. If you turn the heat off, you wont be bringing that heated air into the xj. Just have to remember to cap that vac line so the hvac controls will work normal.
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Old Dec 28, 2011 | 07:21 PM
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Originally Posted by Fsher21

Your heat wont stay on all the time, you will just have coolant flowing through the core at all times. If you turn the heat off, you wont be bringing that heated air into the xj. Just have to remember to cap that vac line so the hvac controls will work normal.
K can you post pics of yours so I can see what I need to eliminate? I can cap the vac hose no prob just need to know what hoses to keep and not to keep
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Old Dec 28, 2011 | 07:44 PM
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you need to two lengths of that( 5/8" I think) heater hose you can buy by the foot at any auto parts store. Get 4 hose clamps for that size as well. Remove the two hoses that runs from the front of the engine, to that heater control valve. One is hooked to the tstat, the other to the pump. Then Remove the two hoses that go into the top and bottom of the heater core. Everything is not disconnected, all that you do not need. I kept mine just for spare hose cause I can lol.

You will have to catch the coolant from your core and all those hoses, so disconnect them in any order that makes that easiest. get a rough idea the distance from the core to the tstat/pump. I think I had 2x 2' lengths of hose, and connected each of them to the core after I flushed it out. I ran them into those clips on the side of the block that the 2 old hoses were in, and up to the front of the engine. I cut them off where needed and clamped them down.

If i remember correct, the bottom nipple on the core (5/8") goes to the metal water pump line, and the larger top nipple (3/4") goes to the tstat housing. I had a t-fitting down the line from the tstat housing that was actually 5/8" and I just had to grease the hose to get it onto the larger connection on the heater core. Yours will be different so you may need 2' of one hose and 2' of the other.

If I missed anything, let me know!
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Old Dec 28, 2011 | 07:46 PM
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Just get 97 heater hoses.
You will need two tees and small lengths of hose to go to the pressure bottle too.
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Old Dec 28, 2011 | 07:50 PM
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Originally Posted by 89Laredo
Just get 97 heater hoses.
You will need two tees and small lengths of hose to go to the pressure bottle too.
Damn should of noticed when that was mentioned above, I have no clue how the pressurized system works
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Old Dec 28, 2011 | 08:19 PM
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Originally Posted by Fsher21

Damn should of noticed when that was mentioned above, I have no clue how the pressurized system works
K I'll get I done tonight
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Old Dec 28, 2011 | 09:50 PM
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Originally Posted by jhampton
stock bottle, the guy at the local jeep store says it will make your heat stay on all the time. i cant see how that would be true but? here in southeast idaho it goes from -20 to 100 so..........
bypassing it will not make the heat on all the time, when doing this you have a supply and return coolant hoses the hose on the top off the pressure bottle put water in the bottle it is supply and the bottom is the return. Make sure after going into the heater core you connect the same hose back to the top of the bottle.

Last edited by freegdr; Jan 30, 2012 at 04:03 AM.
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Old Dec 29, 2011 | 12:31 PM
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From: shelley, idaho
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got it do took my tubing cutter and cut off the HCV and put a nice new peace of rubber on snugged everything down all the hoses are correct and capped the vac hose and away we went drove it to work ran fine so when i go home ill see if it is still working i have no worry's
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Old Dec 29, 2011 | 12:44 PM
  #15  
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Awesome, had no idea that you could do that. I need to replace mine but I can bypass it!!!
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