coolwind57 Posted September 7, 2017 Share Posted September 7, 2017 Ok, I haven't figured this out yet. I've driven my new Comanche for 4-days now since I bought it. Been doing lots of upgrades and I've been having a blast. Here's an issue that I haven't yet figured out and I'd like to run this past you guys. 97K original miles, pretty much all stock engine compartment. Base model, I have idiot lights--no gauges. My water temperature idiot light has been slowly coming on....and I mean a light glow at first then gradually coming on moderately but seemingly not full on. Doesn't look like a full glow to me. The first time, I pulled over worried that I was in trouble. But the engine did not appear to be overheating. No spillage from pressure bottle (I have that nutty closed system that I am trying to better understand), no smells, etc. All appears to be in order with no apparent over heating. Last night I removed the HCV and back flushed the heater core. Cabin heat didn't seem up to par. In doing the flush, I had pinched off the heater hoses going back to engine as to minimizing air pockets throughout the rest of the system. I ran out of light in "burping" the system by raising rear end and loosening that temp sensor, but otherwise refill went ok. I'll burb at work today. What's up with that idiot light? I am only guessing, but did she need a "burping" all along (even before my HCV delete) or did maybe a previous owner install the wrong temperature sending unit (one made for gauges instead of idiot light)? This is all I can come up with in my limited knowledge of this strange closed system. Any ideas, fellas? Link to comment Share on other sites More sharing options...
cruiser54 Posted September 7, 2017 Share Posted September 7, 2017 what happens if you unplug it and drive? Link to comment Share on other sites More sharing options...
coolwind57 Posted September 7, 2017 Author Share Posted September 7, 2017 15 minutes ago, cruiser54 said: what happens if you unplug it and drive? Well, I hadn't tried that. I'll give her a shot and unplug at the sending unit today on my way home from work. What are you thinking here: if its unplugged and still glows that I may have some electrical circuit issues going on? BTW, It doesn't start off glowing. I watched it intently on the drive in this morning. Began glowing as temperature climbed, about 3-4 minutes upon starting and driving down the road. It glowed brightest around 5-6 minutes (driving at 50mph for the next 10 minutes and decreased to a very light glow, pretty-much the remaining 30 minutes of my commute. This "brightest" still looked as if it wasn't a full-on illumination in my opinion. I'm poor, so I'd like to try to figure this out before dropping $15-20 bucks on a new temp sending unit. And of course I want to ensure that nothing damaging is going on too. I am about 25% finished with your connections/grounding-refresh advise. You're a good man, cruiser54. This morning, the interior heat seemed improved after my heater core back flush last night. I'll do the "burp" procedure on my lunch hour. I am beginning to dig the idea of the open-system via Mac's aluminum pressure bottle (with added overflow bottle) upgrade. This current closed system is aggravating to a guy who's not used to seeing this. Seems illogical and over-complicated to me. Link to comment Share on other sites More sharing options...
cruiser54 Posted September 7, 2017 Share Posted September 7, 2017 2 minutes ago, coolwind57 said: Well, I hadn't tried that. I'll give her a shot and unplug at the sending unit today on my way home from work. What are you thinking here: if its unplugged and still glows that I may have some electrical circuit issues going on? BTW, It doesn't start off glowing. I watched it intently on the drive in this morning. Began glowing as temperature climbed, about 3-4 minutes upon starting and driving down the road. It glowed brightest around 5-6 minutes (driving at 50mph for the next 10 minutes and decreased to a very light glow, pretty-much the remaining 30 minutes of my commute. This "brightest" still looked as if it wasn't a full-on illumination in my opinion. I'm poor, so I'd like to try to figure this out before dropping $15-20 bucks on a new temp sending unit. And of course I want to ensure that nothing damaging is going on too. I am about 25% finished with your connections/grounding-refresh advise. You're a good man, cruiser54. This morning, the interior heat seemed improved after my heater core back flush last night. I'll do the "burp" procedure on my lunch hour. I am beginning to dig the idea of the open-system via Mac's aluminum pressure bottle (with added overflow bottle) upgrade. This current closed system is aggravating to a guy who's not used to seeing this. Seems illogical and over-complicated to me. what happens if you unplug it and drive? Link to comment Share on other sites More sharing options...
cruiser54 Posted September 7, 2017 Share Posted September 7, 2017 If you're poor, don't go with Mac's. Get a new radiator for the open system that has the bung for your e-fan switch and get a cheapo recovery bottle. Link to comment Share on other sites More sharing options...
coolwind57 Posted September 7, 2017 Author Share Posted September 7, 2017 36 minutes ago, cruiser54 said: If you're poor, don't go with Mac's. Get a new radiator for the open system that has the bung for your e-fan switch and get a cheapo recovery bottle. Yep, blessed with dashing good looks, but cursed with meager endowment of funds. Initially I thought that Macs was the cheaper route, but as I just checked pull-a-part pricing & eBay, I've found that you're correct. Check this out: **$139 for the Mac's bottle, $23.92 shipping (Yikes!) and a junkyard recovery bottle for $13.95.** TOTAL=$176.87 **$78 new eBay radiator and eBay $17.20 recovery bottle, both free shipping** TOTAL-$95.20 **$39.95 junkyard radiator and a junkyard recovery bottle, $13.95** TOTAL=$53.90 I'll put this on the back burner for now unless the current closed system gives me fits--and then its on like Donkey Kong. Link to comment Share on other sites More sharing options...
cruiser54 Posted September 7, 2017 Share Posted September 7, 2017 Your friendly local Napa should have the radiator for $107. Think ease of warranty etc. The recovery bottle is a 730-4514. Good time to replace heater hoses and eliminate the pesky heater control valve. Napa hoses for a 97 and later XJ are preformed and correct end sizes. Think about putting a full cluster in at some time. Link to comment Share on other sites More sharing options...
coolwind57 Posted September 7, 2017 Author Share Posted September 7, 2017 10 minutes ago, cruiser54 said: Your friendly local Napa should have the radiator for $107. Think ease of warranty etc. The recovery bottle is a 730-4514. Good time to replace heater hoses and eliminate the pesky heater control valve. Napa hoses for a 97 and later XJ are preformed and correct end sizes. Think about putting a full cluster in at some time. Sounds good. Dang 97+ XJ heater hoses cost more than the radiator and recovery bottle! I may consider finding the newest heater hoses from pull-a-part. Link to comment Share on other sites More sharing options...
schardein Posted September 7, 2017 Share Posted September 7, 2017 I replaced the heater hoses on both my XJ and MJ with 97+ models from the junkyard. Even if they were original, they are still newer than my originals. It's been over a year and no issues. Buying local makes it more convenient for warranty/returns, but I also suggest you check prices on Rockauto. If you are buying several things and can get them from the same shipping locations (to minimize shipping costs) you can get some pretty good deals. Sometimes you can add some items like wiper blades, air filter, and spark plugs and have little effect on total shipping cost to get an even better deal. Before I make a purchase (other than at the pick-n-pull) I usually cross reference prices on Rockauto, Amazon, and ebay. Link to comment Share on other sites More sharing options...
omega_rugal Posted September 8, 2017 Share Posted September 8, 2017 The idiot light is a little "analogue" comes on dim when the engine is about to overheat and fully lit when the engine is cooking... Link to comment Share on other sites More sharing options...
cruiser54 Posted September 8, 2017 Share Posted September 8, 2017 Hmmm, but what if it is glowing way before it gets any where before being warmed up? Link to comment Share on other sites More sharing options...
Minuit Posted September 8, 2017 Share Posted September 8, 2017 Start with an infrared thermometer. Need to get another idea of what's going on. They aren't precision devices but should be accurate enough to get a better picture. If the engine is running just under boil-over temp then you need to know. That's still the first I've heard of the idiot light being "analog" so it's very possible you have the wrong sender, and if you had a gauge it would read in the normal range. The closed loop cooling system is a pain in the @$$ and has no benefit over the later, mostly self-burping open loop system. Converting it will save you headaches in the future. Link to comment Share on other sites More sharing options...
omega_rugal Posted September 8, 2017 Share Posted September 8, 2017 2 hours ago, Minuit said: That's still the first I've heard of the idiot light being "analog" so it's very possible you have the wrong sender, and if you had a gauge it would read in the normal range. Its the correct type, but it`s a 30 year old thermistor, it`s resistence may fall before it`s supposed so instead of off-on is more like off-dim-on... i noticed back when the cooling system in my MJ was leaking, i saw the light dim and thougt "is it ON or what?" kept driving and a few minutes later the engine began to boil and suprise, the light was fully on... Link to comment Share on other sites More sharing options...
coolwind57 Posted September 8, 2017 Author Share Posted September 8, 2017 Quick update: Burping the closed system (decline front end, unscrewing Temperature sending unit) didn't work. An air pocket did escape, but it didn't fix my idiot light issue. I noticed that what this thing does is glow brightest upon initially reaching temperature. Then it tapers off a bit to a medium, then very light glow. So light that it is hardly visible when the sun is out brightly. I'll unplug the sending unit for the ride home today, as cruiser54 advised. I have to swing by O'Reilly's later this morning anyhow, and I'm going to go ahead and pick up a new temperature sending unit. Not typically a "throw-money-at-it kind of guy", but hey they're only 11-bucks. I just need some more piece of mind that I'm not melting my engine. Thanks fellas. I'll update. Link to comment Share on other sites More sharing options...
cruiser54 Posted September 8, 2017 Share Posted September 8, 2017 Get an infrared point and shoot thermometer. Always useful. Link to comment Share on other sites More sharing options...
johnj92131 Posted September 8, 2017 Share Posted September 8, 2017 Replacing the 30 year old temp sensor is a good idea. The temp sensor in my 86 diesel turned out to be bad when we fired up the TDI engine. Harbor Freight sells several infrared point and shoot thermometers for $28 or less with their typical 20% off coupon: https://www.harborfreight.com/catalogsearch/result/index/?dir=asc&order=EAScore%2Cf%2CEAFeatured+Weight%2Cf%2CSale+Rank%2Cf&q=thermometer I will likely pickup one this weekend for just over $23. Link to comment Share on other sites More sharing options...
HOrnbrod Posted September 8, 2017 Share Posted September 8, 2017 The dash temp idiot light if working correctly should not act "analog". It's either OFF or ON depending on the coolant temperature switch (not sender) setting. If the light is illuminating in degrees of intensity, the temp switch is either defective internally, or the temp switch and/or dash indicator light have funky grounds. Clean the ground connections up first, then if no help replace the switch. The OEM p/n is J3230408; use an OEM replacement switch if possible. http://www.ebay.com/itm/Mopar-J3230408-Engine-Coolant-Temperature-Sender-/182633410302?epid=169638040&hash=item2a85ccaefe:g:jBsAAOSwjvJZTEM5&vxp=mtr The best fix by far of course is replacing the dash cluster with one with full gauges. Then you will have full "analog" indicators. Link to comment Share on other sites More sharing options...
cruiser54 Posted September 8, 2017 Share Posted September 8, 2017 Yup^^. http://cruiser54.com/?p=110 Link to comment Share on other sites More sharing options...
coolwind57 Posted September 8, 2017 Author Share Posted September 8, 2017 45 minutes ago, cruiser54 said: Yup^^. http://cruiser54.com/?p=110 Will do. Link to comment Share on other sites More sharing options...
coolwind57 Posted September 9, 2017 Author Share Posted September 9, 2017 FIXED! Thank you friends for your help. It came down to a bad temperature sending unit. I popped a new one in and we're doing great now. Link to comment Share on other sites More sharing options...
cruiser54 Posted September 9, 2017 Share Posted September 9, 2017 1 minute ago, coolwind57 said: FIXED! Thank you friends for your help. It came down to a bad temperature sending unit. I popped a new one in and we're doing great now. Great. Glad to hear. You should really do Tips 1 through 5 when you have an hour or so. Link to comment Share on other sites More sharing options...
coolwind57 Posted September 9, 2017 Author Share Posted September 9, 2017 56 minutes ago, cruiser54 said: Great. Glad to hear. You should really do Tips 1 through 5 when you have an hour or so. I"m on it! Link to comment Share on other sites More sharing options...
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