2010 JKU (3.8), just over 217,000 miles on the odometer. Have had a number of issues with the cooling system in the last two years or so, started with a bottle of Blue Devil destroying the radiator. Since then, 2 new radiators, all new hoses, water pump, 2 heater cores, a new fan, fan relay. System was jetted in both directions before replacing everything and I don’t reuse coolant.

Runs like a champ however if I stop briefly—long enough to let engine continue to gain heat but not long enough for it to actually cool down— it won’t start. It will crank and then kinda just fart itself off. If I run into the store for a few mins and come back outside, the temp meter is often well above the normal range.

I went all winter not thinking about this as it was a pretty chilly one in Denver and today it’s nearly 70 and we’ve been giving the Jeep some good lovin today.

Any idea what I should look at first? When I replaced my fan relay about two summers ago, the fan would run after the engine would be turned off but it wouldn’t stop. My engine has always run warmer, I had a lower temp thermostat in there one or two thermostats ago but think now it’s honestly got a fail safe one in it. Might explain why it takes a minute for the heat to get hot…. Damnit

Anyways. Thanks in advance for any help!

**ETA: Sometimes I’ll go to start it and it will act like it’s going to crap out on me however if I give it some gas while cranking it’s usually fine. I run enough sea foam and Lucas injector cleaner through the tank and the engine to feel confident it’s not a fuel delivery issue but the gas pump getting it to go makes me second guess myself.

 

Not sure but it's worth throwing it out there. Take a look and possibly replace Crank Position Sensor. Maybe also cam position sensor but def pull the CPS and clean. A new on is under $20