Jerry Posted June 14, 2010 Share Posted June 14, 2010 I need a shunt in the right direction please guys My new Pioneer('89 4.0L Auto) has the idiot light instead of a proper water temp gauge and it comes on if I'm sitting idling for five minutes on a hot day. Is that normal? It did it while I was in line up for emissions testing the other day so I got the guy to switch on the fans they use to blow air into the radiator and within about 20 seconds the light went out again. Does the idiot light come on well before the motor is really overheating or is engine damage occurring by the time it comes on? I thought I'd get an after market electric fan for it and if the light comes on BEFORE a true overheat then I'd rig the fan to switch from the light. It's got brand new Rad and viscous fan BTW Thoughts? Suggestions? :idea: Thanks :thumbsup: Link to comment Share on other sites More sharing options...
LarryH88bt Posted June 14, 2010 Share Posted June 14, 2010 Your fan should come on before the light I would think. Maybe your fan is busted. And MJ and XJ 4.0's absolutely need that fan or it will get too hot. The fan should come on at about 215? Not sure about the light. Normal is 210. Link to comment Share on other sites More sharing options...
gl1200aman Posted June 15, 2010 Share Posted June 15, 2010 Have you checked the temp sensor for the elec. fan? How about the thermostat? I have an 88 4.0 and I put in a new 2 row radiator and thermostat and in 88 deg. stop and go traffic the temp is not effected, stays around 195. Link to comment Share on other sites More sharing options...
Jerry Posted June 15, 2010 Author Share Posted June 15, 2010 But it hasn't got an electric fan it's got a VISCOUS fan :???: http://en.wikipedia.org/wiki/Fan_clutch Link to comment Share on other sites More sharing options...
bigd44889 Posted June 15, 2010 Share Posted June 15, 2010 it should have both it has cluch fan and next to it there is soposed to be an eletric fan Link to comment Share on other sites More sharing options...
Jerry Posted June 15, 2010 Author Share Posted June 15, 2010 it should have both it has cluch fan and next to it there is soposed to be an eletric fan OK! So I'm missing the electric fan, no wonder it was getting hot while sitting idling! I'll be needing to go down the wreckers yard then and find one. At least it means all the wiring should be there and I can just plug it in :clapping: Thanks for the info :thumbsup: Link to comment Share on other sites More sharing options...
mopwrd340 Posted June 15, 2010 Share Posted June 15, 2010 did you check the clutch fan to see if its working right. if I'm not mistaken your truck might not have came with a electric fan . if it didnt have a/c . :hmm: Link to comment Share on other sites More sharing options...
ComancheKid45 Posted June 16, 2010 Share Posted June 16, 2010 did you check the clutch fan to see if its working right. if I'm not mistaken your truck might not have came with a electric fan . if it didnt have a/c . :hmm: No A/C no E-Fan :smart: Link to comment Share on other sites More sharing options...
Jerry Posted June 16, 2010 Author Share Posted June 16, 2010 Darn! No A/C so maybe it didn't come with an electric fan. The rad and viscous fan are brand new, properly box fresh brand new, so I'm guessing they are in GWO. Apart from the thermostat are there any other common reasons why the overheat light would come on under those conditions? Which are: stationary and idling for approx ten minutes on a medium warm day. Any of you guys out there have the light come on like that? It's fine when on the move. Although I don't have a temp gauge so it could be running hot all the time :dunno: Link to comment Share on other sites More sharing options...
Harper Posted June 16, 2010 Share Posted June 16, 2010 Darn! No A/C so maybe it didn't come with an electric fan. The rad and viscous fan are brand new, properly box fresh brand new, so I'm guessing they are in GWO. Apart from the thermostat are there any other common reasons why the overheat light would come on under those conditions? Which are: stationary and idling for approx ten minutes on a medium warm day.Any of you guys out there have the light come on like that? It's fine when on the move. Although I don't have a temp gauge so it could be running hot all the time :dunno: I was going to suggest that very thing. I don't have the light on mine. I have a gauge instead. But I don't think the light comes on until around 230 or so, maybe a little higher. So you might be running a bit too hot all the time. Sounds like you have a partially blocked radiator that barely does the job while you're moving, and can't handle the heat while standing. Link to comment Share on other sites More sharing options...
MjAllTheWay Posted June 16, 2010 Share Posted June 16, 2010 did you check the clutch fan to see if its working right. if I'm not mistaken your truck might not have came with a electric fan . if it didnt have a/c . :hmm: No A/C no E-Fan :smart: I have no A/C and i have an electric fan so i don't now if thats true Link to comment Share on other sites More sharing options...
ParadiseMJ Posted June 16, 2010 Share Posted June 16, 2010 My truck did not come with a fan either but does have A/C (the PO probably removed it) and a 5 speed. There was a spot for it, the wiring was there, the relay was there. I scored a newer style S-blade fan at the junkyard and it popped right in. In your case the problem sounds more like a fan clutch though IMHO. Rule of thumb, my diagnostics: Overheating on freeway/highway at speed - problem with COOLANT flow. Water pump, clogged channels, radiator. Overheating while crawling, in traffic, under load, slo 'n go and creeping temps - problem with AIR flow which points to fan clutch (or some sort of blockage, bent rad fins, etc.). If you have a newer fan clutch and it's still not cutting it then maybe your new fan clutch is NOT in GWO. BTW - a cooler t-stat will not control max temps. When I converted to open cooling I put in a ZJ HD fan clutch, not the MAX clutch. I don't have a part number, but if you go to NAPA and ask for a ZJ HD clutch they'll likely try to sell you a MAX clutch. The ZJ HD one will fit, the MAX one won't fit. Link to comment Share on other sites More sharing options...
Jerry Posted June 16, 2010 Author Share Posted June 16, 2010 i'll try locking the fan so it can't slip and see if that makes any difference. I think I can rule out any blockages in the radiator as it's only six months old. The PO isn't sure if the thermostat was changed so I'll do that and give the system a flush. There is some bug netting behind the grill, could that cause a sufficient reduction in air flow? Link to comment Share on other sites More sharing options...
driggity Posted June 17, 2010 Share Posted June 17, 2010 did you check the clutch fan to see if its working right. if I'm not mistaken your truck might not have came with a electric fan . if it didnt have a/c . :hmm: No A/C no E-Fan :smart: I have no A/C and i have an electric fan so i don't now if thats true My truck also has an electric fan but no A/C. Link to comment Share on other sites More sharing options...
MjPioneer Posted June 17, 2010 Share Posted June 17, 2010 Just going to toss this out there. I have tested the following setups on my Mj, All tested by me. Stock fans 1 Clutch fan 1 E-fan=Temp-195-205 1 Clutch fan 0 E-fan=Temp-210+ 0 Clutch fan 1 E-fan=Temp-195-205 0 Clutch fan 0 E-fan=temp-210+ (...I wouldn't even try it..again) Daul E fans 0 Clutch fan 2 E-fan=Temp-180-200 1 Clutch fan 2 (mini)E-fan=Temp-180-200 "Light weight" clutch fan 1 Clutch fan 1 E-fan=Temp-205-210 1 Clutch fan 0 E-fan=Temp-210-215 Puller fan 1 Clutch fan 1 E-fan=Temp-200-210 0 Clutch fan 1 E-fan=Temp-210-215 0 Clutch fan 2 E-fan=Temp-205-210 Puller and Pusher combo=Temp-200-210 Taurus fans=Temp-185-205 (If wired wrong they will completly die on you well you are driving...) Currently I run a single E pusher fan and am getting a temp from 195-210 in 85-95 degree heat, stop and go traffic. I have mine wired to run constantly well the truck is running. I will admit it gets right past 210 in heavy traffic but will quickly go under 200 once I start moving. From all the testing I have done over the years I have found it most neccesary to get the heat away from the manifolds rather then the block itself. I would double check every thing in the cooling system before you dive head first into crazy fan set ups. *All test were done by me Mjpioneer. 1989 Mj Comanche Pioneer 4.0/ba10 closed cooling system. Test conducted between the mileage 250,xxx301,xxx* I hope this helps you, and anybody else considering fan set ups. Link to comment Share on other sites More sharing options...
mopwrd340 Posted June 17, 2010 Share Posted June 17, 2010 you could get a temperature gun to check againist the gauge . i looked at my sons freind xj it was showing 240 on the gauge . but it wasnt boiling over any put new sending unit in it still showed the same . i figured the gauge was off and told him to get another instrument panel.my temperature gun said it was sitting at 200 . Link to comment Share on other sites More sharing options...
Jerry Posted June 18, 2010 Author Share Posted June 18, 2010 Just going to toss this out there. I have tested the following setups on my Mj, All tested by me. Stock fans 1 Clutch fan 1 E-fan=Temp-195-205 1 Clutch fan 0 E-fan=Temp-210+ 0 Clutch fan 1 E-fan=Temp-195-205 0 Clutch fan 0 E-fan=temp-210+ (...I wouldn't even try it..again) Daul E fans 0 Clutch fan 2 E-fan=Temp-180-200 1 Clutch fan 2 (mini)E-fan=Temp-180-200 "Light weight" clutch fan 1 Clutch fan 1 E-fan=Temp-205-210 1 Clutch fan 0 E-fan=Temp-210-215 Puller fan 1 Clutch fan 1 E-fan=Temp-200-210 0 Clutch fan 1 E-fan=Temp-210-215 0 Clutch fan 2 E-fan=Temp-205-210 Puller and Pusher combo=Temp-200-210 Taurus fans=Temp-185-205 (If wired wrong they will completly die on you well you are driving...) Currently I run a single E pusher fan and am getting a temp from 195-210 in 85-95 degree heat, stop and go traffic. I have mine wired to run constantly well the truck is running. I will admit it gets right past 210 in heavy traffic but will quickly go under 200 once I start moving. From all the testing I have done over the years I have found it most neccesary to get the heat away from the manifolds rather then the block itself. I would double check every thing in the cooling system before you dive head first into crazy fan set ups. *All test were done by me Mjpioneer. 1989 Mj Comanche Pioneer 4.0/ba10 closed cooling system. Test conducted between the mileage 250,xxx301,xxx* I hope this helps you, and anybody else considering fan set ups. That's some useful MJ testing data! :thumbsup: Link to comment Share on other sites More sharing options...
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