oldrusty Posted December 6, 2008 Share Posted December 6, 2008 I have a question about the open cooling system on my wifes 2000 xj. Is there an easy way to fill the cooling system on the 4.0 ho motors. I had to replace the lower rad hose on our xj tonight and am having a hell of a time trying to get all the air out of the system. I filled it up and drove it and while it isnt over heating I only get heat when the engine is under a load. If you rev the engine above 2000 rpm in park you get instant heat from the vents. I'm thinking I have air in the heater hoses somewhere. I had this problem once before and bled it out through a heater hose, but can't for the life of me remember how i did it. Link to comment Share on other sites More sharing options...
BLHTAZ Posted December 7, 2008 Share Posted December 7, 2008 Actually...you have the closed system. The open system has a radiator cap and is easy to deal with. Here is the write up I did on bleeding the system... viewtopic.php?f=9&t=12311 I have also seen guys talk about filling the system through the upper radiator hose to help avoid getting the air in it, but I am not sure exactly how that works. Link to comment Share on other sites More sharing options...
Wildman Posted December 7, 2008 Share Posted December 7, 2008 I have a question about the open cooling system on my wifes 2000 xj. You should be able to remove the top heater hose (the highest point), and "burp" the system that way. Of course, do it when the engine is cold, and keep filling the radiator until the fluid come out the heater hose, then reconnect it. I have also seen guys talk about filling the system through the upper radiator hose to help avoid getting the air in it, but I am not sure exactly how that works. That's how I fill the closed system, and never had a problem, but I take it off the thermostat neck and when the fluid comes out the neck, stick the upper hose on, and done. Link to comment Share on other sites More sharing options...
oldrusty Posted December 7, 2008 Author Share Posted December 7, 2008 Actually...you have the closed system. The open system has a radiator cap and is easy to deal with. Here is the write up I did on bleeding the system... viewtopic.php?f=9&t=12311 I have also seen guys talk about filling the system through the upper radiator hose to help avoid getting the air in it, but I am not sure exactly how that works. My 89 MJ has the closed system. The wifes 2000 xj has the open system with a radiator cap. Thats the one I'm working on. Link to comment Share on other sites More sharing options...
BLHTAZ Posted December 7, 2008 Share Posted December 7, 2008 Interesting...I didn't think the open system started until 1991 on XJ's or MJ's. Has it been converted or is a late 2000 production that managed to get the '01 stuff? With the open system, I have always just filled it from the radiator cap, squeezed the upper hose a few times to get the air out and then started the engine with the radiator cap still off and waited for the t-stat to open. When the water level drops in the radiator with the t-stat open...fill it up & cap it then make sure the resevior has cooloant in it too. I have never had a problem doing it that way. Link to comment Share on other sites More sharing options...
reson46 Posted December 9, 2008 Share Posted December 9, 2008 Interesting...I didn't think the open system started until 1991 on XJ's or MJ's. Has it been converted or is a late 2000 production that managed to get the '01 stuff? Not sure this statement makes sense. :hmm: He has a 2000 XJ which does have an open cooling system. There is no need to fill it through the radiator hose. Just fill it from the top of the radiator. I had to replace the lower rad hose on our xj tonight and am having a hell of a time trying to get all the air out of the system. I filled it up and drove it and while it isnt over heating I only get heat when the engine is under a load. If you rev the engine above 2000 rpm in park you get instant heat from the vents. I don't think your problem is air in the system. I think you may have a vacuum problem. The vents are vacuum controlled. If you have a broken vacuum line or if the vacuum canister has gone bad it will result in air coming out of the wrong vents or possibly not working at all. Willy Link to comment Share on other sites More sharing options...
BLHTAZ Posted December 9, 2008 Share Posted December 9, 2008 Interesting...I didn't think the open system started until 1991 on XJ's or MJ's. Has it been converted or is a late 2000 production that managed to get the '01 stuff? Not sure this statement makes sense. :hmm: He has a 2000 XJ which does have an open cooling system. There is no need to fill it through the radiator hose. Just fill it from the top of the radiator. Willy You're right... It makes absolutely no sense... :oops: :shake: :wall: I was reading 2000, but for some reason it was registering as 1990... Too many shirts... uhhh... I mean things on my mind right now ;) :yes: Link to comment Share on other sites More sharing options...
oldrusty Posted December 10, 2008 Author Share Posted December 10, 2008 It was air in the system. The heater hose coming off the thermostat housing has a little rise in it that makes it higher than the radiator cap. I pulled that hose off and filled the rad till antifreeze came out of the thermostat housing. Then I held the hose up in the air and filled it up till the antifreeze once again started to run out of the t stat housing. I then held my finger over the end of the heater hose while i moved it down to the nipple and reattatched it. Heater works great now. I'm not sure if this is the factory routing for this hose. If it is I don't understand why jeep would route a heater hose so that it sits higher than the radiator cap. :dunno: Link to comment Share on other sites More sharing options...
BLHTAZ Posted December 10, 2008 Share Posted December 10, 2008 Glad you got it fixed...despite my effortts to confuse you... ;) :thumbsup: Link to comment Share on other sites More sharing options...
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