ghetdjc320 Posted July 15, 2020 Share Posted July 15, 2020 As I write this, I’m sitting on the side of the road waiting for my MJ to cool down. It’s always 85 or so every day here on island. For those of you who know my MJ, the built engine is super clean and has no contaminants in the coolant. I run a flowkooler water pump with billet impeller, Hesco ported thermostat housing, aluminum dual core radiator and an oem 195 thermostat. The truck will run cool for a good long while after starting. Zero issues for probably 30 mins. After some stop and go traffic it starts. Long uphill pulls will also set it off. Once it climbs to 210 it will just keep on going. There are no coolant leaks that I can tell and I’ve done my absolute best to burp the air out of the system. Radiator cap is good and is a 13 or 16lb unit (can’t remember off the top of my head). Any ideas? I have no compression in the coolant or coolant in the oil. I know the oem design is very lacking but this is a bit ridiculous. By the way, running triple 10 fans with controller and optima yellow top battery with 230a Singer alternator so power is not an issue. Link to comment Share on other sites More sharing options...
JimB Posted July 15, 2020 Share Posted July 15, 2020 Is it possible the thermostat is stuck open? If the coolant is flowing to fast for the radiator to cool it can run hot. Especially during stop and go traffic. Link to comment Share on other sites More sharing options...
ghetdjc320 Posted July 15, 2020 Author Share Posted July 15, 2020 Turns out it was the fuse for the cooling fans. I think the fan controller is not cutout for the current draw of the fans. Going to upgrade to a bigger controller. Link to comment Share on other sites More sharing options...
marcial88 Posted July 15, 2020 Share Posted July 15, 2020 Turns out it was the fuse for the cooling fans. I think the fan controller is not cutout for the current draw of the fans. Going to upgrade to a bigger controller. Have you looked into a higher amperage alternator? 1986 Jeep Comanche X4WD GM 2.8L V6Front: Stock Dana 30Rear: Stock AMC 20Los Angeles CASent from my SM-G955U using Tapatalk Link to comment Share on other sites More sharing options...
ghetdjc320 Posted July 15, 2020 Author Share Posted July 15, 2020 2 minutes ago, marcial88 said: Have you looked into a higher amperage alternator? 1986 Jeep Comanche X 4WD GM 2.8L V6 Front: Stock Dana 30 Rear: Stock AMC 20 Los Angeles CA Sent from my SM-G955U using Tapatalk I’m running a Singer 230A. It’s a recent install though so it’s possible this was damaged before the alternator upgrade Link to comment Share on other sites More sharing options...
Pete M Posted July 15, 2020 Share Posted July 15, 2020 4 hours ago, ghetdjc320 said: Turns out it was the fuse for the cooling fans. I think the fan controller is not cutout for the current draw of the fans. Going to upgrade to a bigger controller. well, that would do it. as least you found the problem and nothing got too hurt in the process Link to comment Share on other sites More sharing options...
derf Posted July 15, 2020 Share Posted July 15, 2020 When I had my electric fan in the J10 I ran an 80A relay with 10GA wire. The controller would trigger the relay that would turn on power to the fans. For the power wire I put in a fuse that was sized to the load the fan would put on the system. The fans ran brilliantly. The problem ended up being an over-bored 401 V8 that ran way hotter than the cooling system could handle but the fans were great. Link to comment Share on other sites More sharing options...
AZJeff Posted July 16, 2020 Share Posted July 16, 2020 I used an electric fan in my old 1991 F150. My setup used the two speed fan from a Ford Taurus station wagon with the 3.8, and is a common, low-cost way to get some serious CFM across the radiator. On the "high" speed setting, the fan drew THIRTY (30) amps continuously. Needless to say, that's pretty darned high. Rather than rely on a fuse that might fatigue and fail (even if sized correctly), i used a self-resetting circuit breaker and #10AWG wire to the fan (which is what Ford used on the OEM installation.) You might double check your startup current AND your running current on those three fans in parallel. I am betting it is higher than you think. Link to comment Share on other sites More sharing options...
grouch Posted July 16, 2020 Share Posted July 16, 2020 If it runs hot in traffic it's air flow....If it runs hot at speed, it's water flow. If it runs hot at both....your screwed. Link to comment Share on other sites More sharing options...
omega_rugal Posted July 17, 2020 Share Posted July 17, 2020 26 minutes ago, grouch said: If it runs hot in traffic it's air flow....If it runs hot at speed, it's water flow. If it runs hot at both....your screwed. if it s both you may have low coolant or a pressure leak, higher pressure raises coolant boiling point, if the coolant can not build pressure it overheats other causes could be a stuck thermostat, running too lean, too much spark advance, crowded engine bay the worst would be a blown head gasket it grinds my gears that whenever a car overheats people keep changing thermostats... Link to comment Share on other sites More sharing options...
JustEmptyEveryPocket Posted July 17, 2020 Share Posted July 17, 2020 1 hour ago, omega_rugal said: it grinds my gears that whenever a car overheats people keep changing thermostats *Just joking* Change the thermostat? Hell naw son, you have to take it out completely. That will cure the overheatin' in a hurry! Link to comment Share on other sites More sharing options...
grouch Posted July 17, 2020 Share Posted July 17, 2020 2 hours ago, omega_rugal said: if it s both you may have low coolant or a pressure leak, higher pressure raises coolant boiling point, if the coolant can not build pressure it overheats other causes could be a stuck thermostat, running too lean, too much spark advance, crowded engine bay the worst would be a blown head gasket it grinds my gears that whenever a car overheats people keep changing thermostats... Air in the system will cause sudden overheating too, but Pete probably already knows that . Link to comment Share on other sites More sharing options...
ghetdjc320 Posted July 17, 2020 Author Share Posted July 17, 2020 FYI this problem was due to a burnt out fuse for the cooling fans. Link to comment Share on other sites More sharing options...
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