rocketwheels Posted July 9, 2014 Share Posted July 9, 2014 I haven't laid hands on the truck yet to look for myself, but I need a little advice on an issue. OK, here is his run down... he bought it last fall , Xj 6cyl / auto with A/C. Has the normal cooling system with a radiator cap...NOT the sealed expansion tank system. Truck radiator cooling does ok , remains in good range in moderate weather. BUT, In this 90 plus weather, the truck is up in the 220 range and coolant churns and looses some coolant when shut off. Friend isn't mechanically inclined but does ok...he replaced the thermostat and the radiator cap at my suggestion, but this hasn't changed the symptoms. He doesn't see any signs of oil in the coolant or vice versa. The truck has the clutched fan and the electric fan. The fan clutch checked out ok (tough to turn the fan by hand when really hot) and the electric fan kicks on when the truck gets into the upper temp range.....BUT isn't the electric fan supposed to come on automatically when the A/C is turned on, regardless of the engine temp? Is there some kind of relay for that, outside of the normal temp sending unit? I'm thinking that that perhaps that is the issue, because the temp doesn't get quite as high when he doesn't turn on the A/C. Also, I thought that perhaps the engine coolant needs to be "burped", maybe there is air in the system. Isn't there a trick to burping the system? I really hope he doesn't have a head gasket starting to go bad, blowing exhaust into the coolant, causing it to over pressurize and heat up. So, I've got these items to look at...Cap, thermostat, fan clutch, sending unit, relay ?, "burping" the system. Have I got the basics covered? I plan on catching up with him this weekend to look at the truck, please throw some suggestions my way on what else may be causing the heat up. Link to comment Share on other sites More sharing options...
88ComancheMitch Posted July 9, 2014 Share Posted July 9, 2014 Could always make sure the heater core isn't clogged. Back flushing it might help. I've heard that the radiators go bad and the only symptom is over heating...not any visual signs. Link to comment Share on other sites More sharing options...
Mattwheels Posted July 9, 2014 Share Posted July 9, 2014 hood louvers to let the heat escape, wrap the headers in heat tape to try and keep the heat away from the engine bay, try a 185 or even lower Tstat. and then could remove the clutch fan and add in a second electric, thats about all I can think of for cooling, besides getting a custom radiator. Link to comment Share on other sites More sharing options...
88ComancheMitch Posted July 9, 2014 Share Posted July 9, 2014 I've read in multiple places that the hood louvers don't help with overheating...I'm not sure if that's true or not... Link to comment Share on other sites More sharing options...
Mattwheels Posted July 9, 2014 Share Posted July 9, 2014 it won't necessarily, but it will let heat escape faster after stopping, and they look cool ;) Link to comment Share on other sites More sharing options...
88ComancheMitch Posted July 9, 2014 Share Posted July 9, 2014 it won't necessarily, but it will let heat escape faster after stopping, and they look cool ;) This is why I have Z34 louvers on the way for my MJ :) Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted July 9, 2014 Share Posted July 9, 2014 hood louvers to let the heat escape, wrap the headers in heat tape to try and keep the heat away from the engine bay, try a 185 or even lower Tstat. and then could remove the clutch fan and add in a second electric, thats about all I can think of for cooling, besides getting a custom radiator. Don't do that. Biggest reason is headers are not designed to work like that. Given the fact that most of our Jeeps are running the stock, cast manifolds that are already prone to cracking due to age and stress, wrapping it will just exacerbate the issue. Plus, only ricers do that crap. As far as the T-stat... 195°F is the correct one to use. A properly functioning and well maintained system should run right around 210°F +/- a few degrees regardless of ambient outside temperature. OP, what's the color of the coolant in his system? Is it dark and murky? If so, my first suggestion would be to grab some coolant system flush, Prestone or equivalent. Follow the instructions for the deep clean procedure. Afterward, flush it really well with a garden hose, put 50-70% antifreeze and the rest distilled water back into the system. Run it for a few days and report back. Link to comment Share on other sites More sharing options...
Mattwheels Posted July 9, 2014 Share Posted July 9, 2014 hood louvers to let the heat escape, wrap the headers in heat tape to try and keep the heat away from the engine bay, try a 185 or even lower Tstat. and then could remove the clutch fan and add in a second electric, thats about all I can think of for cooling, besides getting a custom radiator. Plus, only ricers do that crap. well except nascar and pretty much every racing team ;), but because of the use of the tape they found that the tape was pretty much the only thing holding the headers together! now that I've looked it up, I agree Tape is bad, but you can still have them coated with ceramic, or other types of chemicals that will lower the heat in the engine bay and allow the headers to dissipate heat quickly. but now you're talking $$$$ Link to comment Share on other sites More sharing options...
Incommando Posted July 9, 2014 Share Posted July 9, 2014 Lebaron louvers I have no scientific proof but they seem to have helped when I added them .You can see the heat pouring out of them. At speed they probably do less as the heat gets scavenged out anyway but at slow speeds or idling allowing the heat to escape rather than get trapped and bake has to do something. After removing my header pipe and welding up the crack-prone areas as a preventative measure I coated it with some high-heat ceramic stuff to maybe keep the heat in the pipes. Link to comment Share on other sites More sharing options...
nitroxsteve Posted July 9, 2014 Share Posted July 9, 2014 hood louvers to let the heat escape, wrap the headers in heat tape to try and keep the heat away from the engine bay, try a 185 or even lower Tstat. and then could remove the clutch fan and add in a second electric, thats about all I can think of for cooling, besides getting a custom radiator. None of this is necessary these trucks don't run hot if the cooling system is functioning properly. The electric fan should run when the A/C is on not sure what triggers it. What year are you working on? Link to comment Share on other sites More sharing options...
Incommando Posted July 9, 2014 Share Posted July 9, 2014 Many trucks do not have an auxiliary electric fan or A/C. They just have the smallish mechanical fan that only draws over 1/2 of the radiator. I have a Taurus fan for a future conversion. Link to comment Share on other sites More sharing options...
Eagle Posted July 9, 2014 Share Posted July 9, 2014 We NEED to know what year this truck is, because the auxiliary fan operation is different between the Renix-era models and the later HO models. Link to comment Share on other sites More sharing options...
rocketwheels Posted July 11, 2014 Author Share Posted July 11, 2014 nitroxsteve, Eagle .... don't know for sure , but at least mid 90's era. His coolant is really murky. We plan on a flush and new fluid to go with the new thermostat and the new cap. I have a back flush adapter I made many years ago to hook a garden hose into any clamped system starting backward thru the heater core. A good burping of the system will be the final order of the day. He did tell me that the PO claimed to have replaced the radiator a few years ago. We shall see what that does. BTW what is the burping proceedure? I've read it in the shop manual, but any advice? TIA Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted July 11, 2014 Share Posted July 11, 2014 Best way to fill up the closed system is pull vacuum on the whole thing (collapses all the hoses and in theory, removes all the air). They make a device that pulls the vacuum, then using the now void system, pulls the next coolant in. It's quite nifty, actually. Link to comment Share on other sites More sharing options...
Eagle Posted July 11, 2014 Share Posted July 11, 2014 Burping is for the Renix-era closed system, not the later open system. We still don't know what year this truck is. Link to comment Share on other sites More sharing options...
rocketwheels Posted July 12, 2014 Author Share Posted July 12, 2014 Eagle, talked to him this eve....2000 model, gonna flush and review tomorrow evening. Link to comment Share on other sites More sharing options...
91Pioneer Posted July 12, 2014 Share Posted July 12, 2014 I own one of these tools, VERY handy to have. Oddly I did not use it when I refilled my Renix system LOL I used it on my Ford and whoo boy it's pretty slick. It literally sucks the new coolant right out of the jug and into the system, and yup the hoses collapse when they are vacuumed. UView 550000 Airlift Cooling System Leak Checker and Airlock Purge Tool Kit Link to comment Share on other sites More sharing options...
reece146 Posted July 12, 2014 Share Posted July 12, 2014 Eagle, talked to him this eve....2000 model, gonna flush and review tomorrow evening. MY2000 could be the infamous 0331 cylinder head casting crack issue. Inspect the coolant and exhaust for signs of contamination. Link to comment Share on other sites More sharing options...
rocketwheels Posted July 12, 2014 Author Share Posted July 12, 2014 Ok, flush, refill, new cap and a new mech fan clutch.....truck now runs just above 200 at regular road speeds and sits in traffic at around 21 (oops 210 , danged fat fingers ), already an improvement from what it was doing...we'll watch and wait to see what happens over the next few days. Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted July 13, 2014 Share Posted July 13, 2014 Nice! Glad to hear it. :thumbsup: Keep us posted. Link to comment Share on other sites More sharing options...
rocketwheels Posted July 13, 2014 Author Share Posted July 13, 2014 BTW...the electric fan is not comming on solid when the A/C is turned on....it only runs sporadically as it does just like when the A/C isn't on. Link to comment Share on other sites More sharing options...
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