Drahcir495 Posted February 17, 2009 Share Posted February 17, 2009 Just when I thought I had nothing to worry about with my Comanche's cooling system - :headpop: . I had a guy tell me in traffic that I was leaking coolant bad - he was right. The bypass valve broke -> Image Not Found Granted the piece is 20 years old, but why did they make these out of plastic? My question is that if I by-passed the bypass valve - actually I cut it off on the side of the road and reconnected the hose like this -> Does this now mean I have the cab heater on all the time or off? The replacement valves are all metal now at between 35 - 45 bucks :eek: . All the ones at the JY broke in the same place. I am going to wait to find a newer metal one in the JY for now. Link to comment Share on other sites More sharing options...
Ed in North Ga. Posted February 17, 2009 Share Posted February 17, 2009 I'm probably wrong, but- from what I remember, the valve opens with vacuum- if theres vacuum-the waters flowing to the heaterbox. The vacuum itself is only "off" if the control on the HVAC is off- any other position, the waters flowing(and even then, I think some sneaks past). the temp is controlled off a vent flap inline within the heater assembly- anyways, thats the way it worked on my old 89XJ- think of it this way, if you turn the AC on, you can control the cold to heat- if thats the case, the heaterbox is flowing hot water, even with the AC on. I always carried a 3way pipe connector, for cases just like what happened to you. Link to comment Share on other sites More sharing options...
mvusse Posted February 17, 2009 Share Posted February 17, 2009 If it's a Renix, you can do without the valve without any side effects. Just plug the vacuum hose with a golf tee. On the HO (Chrysler) engines, I have heard that the valve is indeed necessary, but I have not verified this on my Cherokee yet. Link to comment Share on other sites More sharing options...
88XJSport Posted February 17, 2009 Share Posted February 17, 2009 Drahcir495 with another helpful thread! :clapping: I am planning on eliminating the valve this summer. Can you take a better pic or explain how you connected the hoses together?? Thanks!!! Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 17, 2009 Share Posted February 17, 2009 In the 1997 models and up the water control valve was eliminated entirely. I junked mine years ago and installed a set of 1997+ heater hoses, and plugged the vacuum line. I get better heat now, no ill effects from excess heat in the cabin in summer, and the constant flow thru the heater core adds a bit more coolant volume to the system. Junk the valve, just another potential source of problems. We have enough of these as it is.... :cheers: Link to comment Share on other sites More sharing options...
jtdesigns Posted February 17, 2009 Share Posted February 17, 2009 I'm probably wrong, but-from what I remember, the valve opens with vacuum- if theres vacuum-the waters flowing to the heaterbox. The vacuum itself is only "off" if the control on the HVAC is off- any other position, the waters flowing(and even then, I think some sneaks past). the temp is controlled off a vent flap inline within the heater assembly- anyways, thats the way it worked on my old 89XJ- think of it this way, if you turn the AC on, you can control the cold to heat- if thats the case, the heaterbox is flowing hot water, even with the AC on. I always carried a 3way pipe connector, for cases just like what happened to you. Its the other way around.. No vacuum water flows.. vacuum present shuts valve off.. It defaults to open if theres no vacuum line attached. Link to comment Share on other sites More sharing options...
Akula69 Posted February 17, 2009 Share Posted February 17, 2009 Mine broke while I was fooling with the vaccum lines and scalded the $#!& out of me, and then I replaced it with a piece of hose that had a 90 degree bend it it from the auto zone. works fine and like hornbrod said, keeps the coolant flowing throught the heater core. Link to comment Share on other sites More sharing options...
Randy in Maine Posted February 17, 2009 Share Posted February 17, 2009 How do you get reservoir coolant water back into the system? Link to comment Share on other sites More sharing options...
Sir Sam Posted February 17, 2009 Share Posted February 17, 2009 How do you get reservoir coolant water back into the system? Through that little hose attached to the coolant reservoir in the picture. He has an open system. Link to comment Share on other sites More sharing options...
HOrnbrod Posted February 17, 2009 Share Posted February 17, 2009 This is true. :D Link to comment Share on other sites More sharing options...
ratrapp Posted February 17, 2009 Share Posted February 17, 2009 i bypassed mine as well.after the 3rd valve went out in 10 years i got tired of it.i also used the newer cherokee hoses.i have more heat now than ever and no more control valves to worry about.like everyone says all the valve does is cut water flow off when the a/c is on but my a/c died years ago so it doesn't matter to me anyway. Link to comment Share on other sites More sharing options...
BIGMASS Posted February 17, 2009 Share Posted February 17, 2009 If you are bent on keeping the valve, go to the junk yard and pull one from an old Cordoba. They are all metal and when the valve is open it is all the way open. But I still ditched mine altogether. Link to comment Share on other sites More sharing options...
UNL1MTD Posted February 17, 2009 Share Posted February 17, 2009 Will bypassing the valve lead to a hotter cab during the summer months even with the heat off? Stupid question, but without AC it concerns me. Link to comment Share on other sites More sharing options...
wranglercory Posted February 17, 2009 Share Posted February 17, 2009 You will have more heat in the cab just due to the fact the coolant will be flowing through the heater core. It may not be all that noticeable but it will be hotter at the heater core. The sole reason behind having one is to stop the coolant from getting to the heater core with AC on but if you bypass the bypass youll have coolant constantly going to the heater core. I have one in my garage if you would like we could work out a deal. Link to comment Share on other sites More sharing options...
Sir Sam Posted February 17, 2009 Share Posted February 17, 2009 Will bypassing the valve lead to a hotter cab during the summer months even with the heat off? Stupid question, but without AC it concerns me. I actually add a valve, a big bass ball valve, onto my 97+ Cherokees because of the heat buildup from the hot water circulating. I think its a VERY noticeable different with or without the valve. Link to comment Share on other sites More sharing options...
Drahcir495 Posted February 17, 2009 Author Share Posted February 17, 2009 Drahcir495 with another helpful thread! :clapping: I am planning on eliminating the valve this summer. Can you take a better pic or explain how you connected the hoses together?? Thanks!!! 88 :wavey: , all I did has hack saw the valve out of the piece and re-connect the hose. It now looks like a a 3way pipe connector that Ed in North Ga. talked about - good idea by the way Ed :clapping: Link to comment Share on other sites More sharing options...
mvusse Posted February 17, 2009 Share Posted February 17, 2009 Yes, technically the cab will be warmer as there will be a hot heater core under your dash, enclosed in ducting. No, I could not notice the difference. And I have no AC. Link to comment Share on other sites More sharing options...
Ed in North Ga. Posted February 17, 2009 Share Posted February 17, 2009 Drahcir495 with another helpful thread! :clapping: I am planning on eliminating the valve this summer. Can you take a better pic or explain how you connected the hoses together?? Thanks!!! 88 :wavey: , all I did has hack saw the valve out of the piece and re-connect the hose. It now looks like a a 3way pipe connector that Ed in North Ga. talked about - good idea by the way Ed :clapping: oddly enough, Ive given away more of my spare parts, than Ive needed to use....I dunno if its upkeep or just plain taking care of your vehicle, but geezzz, some people have no idea on what a "spare" anything is. Link to comment Share on other sites More sharing options...
88AMComanche Posted February 27, 2012 Share Posted February 27, 2012 silly idea........But.......What about putting a 2 way On/off valve just before the heater core? That way during the winter just turn the vale to ON, & sometime before summer turn the valve OFF .same purpose as a HCV but it would be done manulaly & with almost no chance of it going bad. I could handle popping the hood once every few months & turn it on or off. :banana: Link to comment Share on other sites More sharing options...
cruiser54 Posted February 28, 2012 Share Posted February 28, 2012 silly idea........But.......What about putting a 2 way On/off valve just before the heater core? That way during the winter just turn the vale to ON, & sometime before summer turn the valve OFF .same purpose as a HCV but it would be done manulaly & with almost no chance of it going bad. I could handle popping the hood once every few months & turn it on or off. :banana: No need to. Just bypass the original HCV. Heat is controlled by the blend air door, not the HCV anyway. I live in Arizona and have bypassed many HCVs with no ill effects. Real cold AC. Link to comment Share on other sites More sharing options...
Eagle Posted February 29, 2012 Share Posted February 29, 2012 silly idea........But.......What about putting a 2 way On/off valve just before the heater core? That way during the winter just turn the vale to ON, & sometime before summer turn the valve OFF .same purpose as a HCV but it would be done manulaly & with almost no chance of it going bad. I could handle popping the hood once every few months & turn it on or off. :banana: Not a silly idea at all. And if you know how to solder, eliminating the plastic is easy -- a copper tee, a couple of very short lengths of copper tubing, an elbow or two, and you're done. A ball valve as a seasonal shut-off can be added anywhere in the hose, or made up as part of the copper 3-way fitting. Link to comment Share on other sites More sharing options...
Exgrayxj Posted March 5, 2012 Share Posted March 5, 2012 An engine compartment that clean should be against the law. :bowdown: :bowdown: Link to comment Share on other sites More sharing options...
91Pioneer Posted December 7, 2014 Share Posted December 7, 2014 In the 1997 models and up the water control valve was eliminated entirely. I junked mine years ago and installed a set of 1997+ heater hoses, and plugged the vacuum line... Hey hornbrod, I realize I'm bumping this thread a bit LOL... however I was researching this and plan on buying the same hoses that you have. 99% of the time I'm a "keep it stock, OEM" type of guy but in this case I know the stock valve is probably more bad than good (stale coolant, restriction, complicated, etc.). What brand of hoses did you put in? Looking online it seems choices are OEM, Gates, Goodyear and Dayco. I'll probably just go with whoever is cheapest. I wanted to point out FYI that you have your hoses switched compared to the 97 XJ factory service manual. Granted it's not a big deal, but if something flows top to bottom you have more chance of air being caught in there compared to flowing from bottom up. Although the diagram could be wrong I suppose... FSM diagram: Link to comment Share on other sites More sharing options...
HOrnbrod Posted December 7, 2014 Share Posted December 7, 2014 That's odd. I used OEM hoses and installed them as shown below in the parts manuals for 1997 and up. The hoses are preformed and are of different diameters, 5/8" and 3/4". One of the diagrams is wrong. Your diagram looks like it's for a 2.5 engine; the radiator is wrong. Anyhow, it's been working just fine as I have it for many years. Anyone have a 97 4.0 and up XJ? Could you eyeball the heater hose runs? Gracias. Link to comment Share on other sites More sharing options...
91Pioneer Posted December 7, 2014 Share Posted December 7, 2014 Hmmmm well OK if they are different sizes then they should only fit one way. You're right though about the rad being wrong now that I look at it. Interestingly part #2 is different from my 91 with the valve to the 97-01 hoses. I'm pretty sure the hoses will fit in the little plastic holder though. Link to comment Share on other sites More sharing options...
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