Hello folks. I’ve recently started taking my 2012 kk on trails in SoCal, so of course I’ve been upgrading. From what I’ve learned about the 3.7 overheating is a common problem, and causes many problems with these engines. My experience so far has reinforced this as I have overheated a few times. I expected to run into issues since I doubt this vehicle has ever been off-road before this year. The cooling system immediately showed itself as a week link. I changed the water pump not that long ago, and just recently replaced the radiator. It was definitely partially clogged. I thought this might be sufficient but it still overheated on a trail, so I just dropped in a mechanical fan to see if that will do it. Haven’t been out since to test it since I need to replace the cats, which may be exacerbating the problem. That long lead up was just to explain why I’ve been thinking about flex fuel conversions. As I understand it alcohol would reduce the running temp. I’ve seen an awful lot of Chrysler vehicles with flex fuel badges lately, so the question is has anyone cobbled together a flex fuel liberty or know if any 3.7s ever had that option? I know it can be done with aftermarket parts, but the costs are a bit high.
Flex fuel
- Thread starter Okok
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
3.7’s never had the flex fluel option, but some 4.7’s may have had it towards the end. Somebody can correct me on that if I’m wrong. Though 4.7’s and the 3.7 share some similarities, the 4.7 had two spark plugs per cylinder and some other major differences. I wouldn’t want to try using any fuel other than regular unleaded gasoline with my 3.7. The ECM wouldn’t know how to compensate and set the fuel trim and EtOH would mess with the oxygen sensors at the very least. Of course even regular gas can have upwards of 10% ethanol these days.
The mechanical fan should do the trick and you shouldn’t have to worry about any other mods to keep it cool. I’ve never had my engine overheat since installing it, and I do wheel it on some steep trails in PA for my job.
Check to make sure your radiator has orange coolant in it (Mopar HOAT or Zerex G05). If it’s green, it is a “universal” coolant that will react with HOAT and create globs that can clog up your radiator. Use HOAT only for effective cooling and get the green stuff professionally flushed out if you have it.
The mechanical fan should do the trick and you shouldn’t have to worry about any other mods to keep it cool. I’ve never had my engine overheat since installing it, and I do wheel it on some steep trails in PA for my job.
Check to make sure your radiator has orange coolant in it (Mopar HOAT or Zerex G05). If it’s green, it is a “universal” coolant that will react with HOAT and create globs that can clog up your radiator. Use HOAT only for effective cooling and get the green stuff professionally flushed out if you have it.
Last edited:
As I understand it due to the addition of ethanol to almost all pump gas these days the fuel systems of pretty much every vehicle these days can handle e85, it’s just a Matter of delivering the correct amount of fuel for the ratio of ethanol to gas. I could buy an aftermarket ecu, a sensor for the fuel line, possibly larger injectors and fuel pump if necessary (more ethanol necessitates more fuel), and have all that tuned. If I had money I wanted to burn I would try it out for fun, but I’m afraid that project is below suspension, wheels and tires, lockers, winch etc. on the list of priorities. If however I found out that I didn’t have to upgrade the injectors and fuel pump, and I could pick up a used oem ecu and sensor that could be retrofitted that project becomes much cheaper. I was hoping someone knew about ecu compatibility and injector flow rates essentially.
thanks for the heads up about the coolant. It was explained to me at the auto parts store that the universal coolant didn’t have the additives that that react poorly with the hoat coolant, which is what makes it “universal.” The conflicting info is concerning, but I intend to get a full flush soon and stick with one coolant from here on out so I shouldn’t have to worry about it.
