Bansheemanche Posted March 13, 2008 Share Posted March 13, 2008 Ok my truck has been overheating since yesterday. I topped off the coolant and it still overheats. I have a mechanical and electrial fans. I notice when my gauge hits the middle (the gauge has been off since I bought it) I popped the hood and the mechanical fan is running but the electrical fan isn't. I am assuming that is should. Would this cause a overheating issue if it didnt run? I know it ran before so what happened. It didnt start overheating till yesterday when I went mudding with it. I made sure the radiator was clear of mud and ofter stuff. So would that be this issue or what else, like a t-stat or water pump? Maybe a temp sender or sensor or a relay or the whole electrical fan? Thanks, Zack Link to comment Share on other sites More sharing options...
mvusse Posted March 13, 2008 Share Posted March 13, 2008 The mechanical fan by itself should be able to keep it from overheating. If it is a factory installed electric fan, I think that is for the AC. I would start with the cheapest part, and check the t-stat first. Link to comment Share on other sites More sharing options...
juan Posted March 14, 2008 Share Posted March 14, 2008 the electric aux.fan on older xj/mj's does not come on untill 210 / 220 degrees which is to late in my opinion - this is the way the factory did it. Now I did modifyed it and installed my own switch to manually turn the fan on once the temp gauge starts to climb. good luck Link to comment Share on other sites More sharing options...
Bansheemanche Posted March 14, 2008 Author Share Posted March 14, 2008 Ok so factory didnt do it till 210-220? So I possibly didnt go over that yet? It blew at the upper radator hose where is connects to the radator. The hose and all that is fine but it has one of those crappy clamps that you need pliers for to get undone and it is pretty far back. I need a new clamp for that. I will try a t-stat first but I find it is kind of wierd that it was hot after I went wheeling. I will admit I was pretty hard on my mj. 5K shifts sometimes and pulling out my friends pathfinder (hehe). I don't think a T-stat would just close and not open up at those temps. I installed a tach and next is a temp gauge after I fix this stuff. Thanks, Zack Link to comment Share on other sites More sharing options...
Bansheemanche Posted March 14, 2008 Author Share Posted March 14, 2008 Bump. All help is needed with this mang. Link to comment Share on other sites More sharing options...
purplexj Posted March 26, 2008 Share Posted March 26, 2008 I had an overheating prob and tried to flush it. When I openend the petcock nothing came out. I removed the rad and flushed it with a garden hose. There was so much crud in it that I had to use a wire/stick/screw driver at the petcock to get it to run out. Also connected garden hose to heater hose with lite psi to clean heater core. This solved my probs. Later on I had the prob of aux fan not coming on, which was due to bad ground at the a/c compresser. The aux fan should come on at about 210, if it does'nt you will overheat. I now have changed the therm and added a switch to control the aux fan. Everthing works great now and I never need to use the switch but it's good to know it's there. Link to comment Share on other sites More sharing options...
purplexj Posted March 26, 2008 Share Posted March 26, 2008 Forgot to mention My fan shrould was broken, I replaced it and a new rad cap. Upgraded to 94 up mech fan and clutch that I got for free from friends jy. All of these fixes I'm sure helped , but the main was the clean rad. Or possible in your case the aux fan not comming on. Hope that snow in your pic isnt recent, it's about 52 here today. Link to comment Share on other sites More sharing options...
HOrnbrod Posted March 29, 2008 Share Posted March 29, 2008 The aux fan should come on at about 210, if it does'nt you will overheat. I now have changed the therm and added a switch to control the aux fan. Everthing works great now and I never need to use the switch but it's good to know it's there. The aux fan on the 91+ HOs doesn't come on until 215*-220*, way too high for me. It can be even higher if the coolant sensor in the thermostat housing has calcified deposits on the sensor tip. I fixed this problem today. The aux fan relay in the HOs is in the PDC. This relay is triggered from a ground to it's coil from pin 31 on the ECU when the temp reaches the high limit (or you turn the A/C on). I simply soldered in a wire to the pin 31 ECU output wire and ran it through a spare switch on the dash to ground to energise the fan when I want. I think the Renix models w. the aux fan are triggered the same way through a relay but use 12V from the ECU, not a ground signal. So this can work on the Renix models too. Good insurance to have when stuck in bumper to bumper traffic. :cheers: Link to comment Share on other sites More sharing options...
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