Jeep Strokers

Fresh 4.6 build. Will run all day in stop and go traffic or idling up some knarly trail in 110 degree weather and never go over 195. Pull a hill on the highway or travel down the highway at 3000 rpm and it will over heat in about 5 minutes. Temp comes down if I slow down.

What I have done: new flow cooler water pump, high flow 194 thermostat, new double row aluminum radiator, new CPS, flushed the holy hell out of the system with Red Devil Flush (3 times), added wetting agent, running 60/40 water to coolant ratio.

Engine sounds great. Pulls like a beast. No stutters, backfires or misses. However, it idles past 12 degrees advanced, more like 20 degrees.

Have you tried backing the timing down(not even sure it's possible without a crank sensor mod)? I've never had the issue, but I've heard friends have to back their timing down because at speed they would run hot. I don't actually know the base timing for a 4.0 is. I'm guessing it can't be more than 15* btdc.

Clogged exhaust, transmission issues, and coolant cavitation would be some other things I'd be looking at.

Are you still running the stock, original mechanical fan-clutch? If so, replace it.

Any updates?

Possibly running lean? what size fuel injectors are you running?

More than once I have seen the wrong water pump installed. Be sure that it is the correct rotation for your engine. The wrong rotation will cool a little bit. But, at higher loads and engine speeds it quickly over heats.

KarmaKannon1 wrote: ↑July 29th, 2020, 7:52 am Have you tried backing the timing down(not even sure it's possible without a crank sensor mod)? I've never had the issue, but I've heard friends have to back their timing down because at speed they would run hot. I don't actually know the base timing for a 4.0 is. I'm guessing it can't be more than 15* btdc.

It is not possible, at least how you are thinking. And retarding timing increases temps, not decrease.

KarmaKannon1 wrote: ↑July 29th, 2020, 7:52 am Have you tried backing the timing down(not even sure it's possible without a crank sensor mod)? I've never had the issue, but I've heard friends have to back their timing down because at speed they would run hot. I don't actually know the base timing for a 4.0 is. I'm guessing it can't be more than 15* btdc.

Clogged exhaust, transmission issues, and coolant cavitation would be some other things I'd be looking at.

New header, exhaust, cat, straight flow muffler.

RubiMikeTX wrote: ↑July 31st, 2020, 7:53 pm Are you still running the stock, original mechanical fan-clutch? If so, replace it.

Tried stock fan and two electric fans with shroud. Electric fans worked better, but still can't go freeway speeds without overheating.

dwg86 wrote: ↑September 3rd, 2020, 8:50 am Possibly running lean? what size fuel injectors are you running?

Bosch flow rates @ 43.5 psi / 3 bar24.7 lb

Bertismyname wrote: ↑September 20th, 2020, 11:58 am More than once I have seen the wrong water pump installed. Be sure that it is the correct rotation for your engine. The wrong rotation will cool a little bit. But, at higher loads and engine speeds it quickly over heats.

Used stock pump, then tried high flow. No difference.

Russ Pottenger wrote: ↑August 29th, 2020, 12:37 pm Any updates?

Barely stays at 220 going 3000 rpm down freeway in 60 degree weather. Have been thinking about trying an oil cooler or maybe one big electric fan instead of the two smaller. Fan doesn't seem likely problem as I'm doing 65 down the freeway. Tried removing lights and winch but didn't help. Maybe my ecu is bad. Everything works great. Just over heat at high rpm. Jeep is nearly unusable on freeway during summer.

Sounds silly but have you replaced your radiator hoses? I have seen the inside of a hose tear loose and with normal flow/low RPM they seem to cool fine but with higher RPM and faster water flow the inner lining balloons up and blocks the flow of coolant. Also how old is the radiator? Water scale buildup possibly?

bnelson wrote: ↑November 19th, 2020, 2:25 pm Sounds silly but have you replaced your radiator hoses? I have seen the inside of a hose tear loose and with normal flow/low RPM they seem to cool fine but with higher RPM and faster water flow the inner lining balloons up and blocks the flow of coolant. Also how old is the radiator? Water scale buildup possibly?

Yeah, started with spendy silicone hoses, but switched to oem hoses just to see if that would work.

Radiator is brand new double core oversize