sinkrun Posted October 23, 2011 Share Posted October 23, 2011 My MJ is over heating at idle speed or crawling thru the wood slow. No air manual fan 4.0 about a 5 year old rad from advance. Just started this and its been cool here when it was 100 in did not do it. Just a idiot light no gauge yet any ideas before I throw money at it? Link to comment Share on other sites More sharing options...
Blue88Comanche Posted October 23, 2011 Share Posted October 23, 2011 check the thermostat it maybe stuck closed Link to comment Share on other sites More sharing options...
kyleag89 Posted October 23, 2011 Share Posted October 23, 2011 Have you checked to see if your fan clutch has a good amount of resistance? Link to comment Share on other sites More sharing options...
sinkrun Posted October 24, 2011 Author Share Posted October 24, 2011 No I never thought about that will do in the morning and throw a thermostat stat in. Link to comment Share on other sites More sharing options...
Eagle Posted October 24, 2011 Share Posted October 24, 2011 If it only overheats at idle but not when rolling down the road, the thermostat isn't stuck closed. More likely the viscous fan clutch isn't spinning the primary fan fast enough. They do get tired. Overheating at idle is the classic symptom. Link to comment Share on other sites More sharing options...
btm24 Posted October 24, 2011 Share Posted October 24, 2011 Is it really over heating or is it just over flowing from the pressure bottle? I know mine used to "over heat" all the time t idle untill I replaced that bottle. The old one had one or more checks in it which would release the pressure. Â Brandon Link to comment Share on other sites More sharing options...
Jerry Posted October 24, 2011 Share Posted October 24, 2011 Is it a closed system? If it is, have a real close inspection of the radiator for pin hole leaks. That's all it took for my closed system to lose enough pressure to overheat when working hard or crawling but still being fine on the highway. Drove it like that for ages occasionally having to stop and let it cool a few minutes if the light came on. Wasn't until i drove in snow that I spotted a tiny tiny tiny tiny green drip in the white stuff coming from a real fine almost invisible mist spraying out a crack in a radiator seam :wrench: Link to comment Share on other sites More sharing options...
sinkrun Posted October 24, 2011 Author Share Posted October 24, 2011 Its a closed system converted to open with a inline filler neck pressure bottle has been eliminated. The fan clutch when hot is quite free forgot to check it when cool. It should not be free when hot right? Link to comment Share on other sites More sharing options...
Eagle Posted October 24, 2011 Share Posted October 24, 2011 Its a closed system converted to open with a inline filler neck pressure bottle has been eliminated. The fan clutch when hot is quite free forgot to check it when cool. It should not be free when hot right? Right. Link to comment Share on other sites More sharing options...
Jerry Posted October 24, 2011 Share Posted October 24, 2011 You should be able to hear the fan working and feel lots of air movement when it's hot. You could try picking up an xj/mj electric fan from a local P&P, throw it in wired direct to the batt (with a fuse!) and see if you still get overheating :cheers: Link to comment Share on other sites More sharing options...
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