And if you have tried a 180 have you noticed any problems. The possibility of running one was discussed a few months back and it was mentioned that the computer may not like it and that there could be some problems. If you have run one has the JK run any cooler because of it?

 

Cooler thermostats are good for performance but bad for engine oil sludging. Water in the oil won't boil off as effectively which is a big cause of oil sludging.

I think the superchips flashpaq allows you to adjust your fan turn on/off temps to match a cooler thermostat if you wanted to give it a try.

 

Are you actually having overheating issues?

 

I guess it depends on how youy define overheating issues. If you mean a serious failure, blown hoses, boiling over etc then the answer is no, not yet. However since I installed the Aeroforce Interceptor and am actually seeing the temps the computer sees I think it is running hotter than I want. The gauge, if you can call it that, is programmed to be deceptive in that it reads exactly the same (straight up) from 180 to 220. I undersatand some are a little tighter and read the same from 185 to 215. But I am seeing temps in the 230 range when on slow trails while the ambient temp is in the 50's and 60's. I am very concerned that when I'm out in the desert in July and August and the temp is well over 100 that I will then be running hotter than is prudent. If it never got over 210 or so I could live with that but it doesn't seem capable of holding that. There is a reason Jeep engineers tweaked the gauge to give meaningless readings.

My gut feeling is that the JK has too small a radiator, perhaps insufficient fan capacity and misprogrammed fan cut in speeds. It seems to be ok when you have decent speed and there is reasonable airflow. But it becomes marginal when you are on slow trails. FWIW I notice the same thing with the trans; especially when in 4H or 2H. It seems to be ok when in 4Lo and it;s not working hard. Doing the same trail at the same ambient I have notice a 65 degree difference in trans temp between 4Hi and 4Lo. Since the trans is bolted to the engine it can transfer heat to the engine making things worse. I have seen the engine get up to 240 when the trans got up to 250 (50 degrees ambient, 4Hi, 15 mph, climbing 2000 ft over 5 miles) So i think both issues need to be addressed. I would rather not have to go to 4Lo to deal with this issue because for long offroad trips there are times when I want to stay in 4Hi as often as possible to keep the fuel consumption down.

I think you might be deluding yourself if you think the JK is not on the ragged edge as far as cooling capacity. And this is with relatively new vehicles; it will only get worse with time. I'd prefer to prevent the problem than deal with it 50 miles from a road. But then being inthe west where we have vast tracts of land to play on and where it can get damn hot perhaps I look at it differently.

 

I personally haven't had temperature problems, but in regards to your topic. If you're seeing temps in the 200-230 range, a thermostat that opens sooner isn't really going to help with your peak temperatures. Even a 195 thermostat is wide open within your operating temps. Thus the cooling system is using 100% of it's capacity. To lower your maximum temperatures, you need to increase your cooling capacity.

Lower opening thermostats are better for performance IF you reprogram ("chip") the engine map to utilize those cooler temperatures to make more power.

 

He is 100% correct. I would make sure the Fan is operating correctly (2 speeds) and that there is nothing blocking the airflow to the radiator. Depending on your mileage you may want to do a Radiator flush too. My Wife's 60k old Honda pilot was running very hot lately and a simple flush of the radiator cleared that right up.

Today's engines are designed to run in the 200-220 range, you get better emissions and mileage because the burn is a little more efficent.

 

So I guess theoretically, if the 195 thermostat is fully open at 195, and if you had adequate fan and radiator capacity, the temp should be maintained at 195 or close to it. So if we brought the fan cut in at 195 or even a little lower, given sufficient radiator capacity, the temp should again be maintined close to 195. And if it can't be maintained there it would be an indication of an inadequate radiator.

So if the radiator is of inadequate capacity what is the best course of action? The Griffin is available but isn't cheap. I recall we used to be able to get local shops to build us what we wanted. Oft times a big 4 row desert cooler that worked great. Are there any other alternatives?

 

Unfortunately in order to save like $2 car companies use plastic tanks on their radiators. They are now disposable units unlike the radiators from the 60's and 70's that had brass tanks.

You can add one of those huge aluminum radiators but they are way too expensive. Any other alternative would require alot of research on your part (seeing what is larger and will fit in the space. Then you would probably have to fab the mounts, tranny cooler lines (if you have an auto) sensors etc.

I have not heard of anyone having much trouble with the engine overheating, that is probably why aftermarket companies do not make more. I have heard of people adding extra tranny and PS fluid coolers though.

Another thing to think about is with a 195 degree thermostat you may not pass emissions since your engine is not up to it's correct operating temperature. If you engine stays at 195 your computer may think that is still in warm-up mode (faster idle ect) and also all of the emissions control equipment is designed for higher temperatures.

 

I think if the radiator was adequate it would keep the temp down in the 195-200 range; and I'd be happy with that. I spoke to a Griifen Radiator tech yesterday. He said that the stock JK radiator was just simply short of cooling capaicity. Their radiator is aluminum and 1 1/2 thick. The one the sell for the JK with 3.8 is the same as they provide for the Hemi conversion except for the location of the hoses (the Hemi's are on the side). He said that they are working fine on 6.1 Hemi conversions that have been sent over to the middle east and so have plenty of excess cooling capacity.

He did suggest programming he fan to come on sooner or upgrading the fan and looking for something that could move about 3500 cfm. I wonder what the stock fan is rated at?

I imagine a Griffin and hood louvers would be ideal.

 

Hey Chuck I have the griffin radiator and while I believe it is a lot better at not getting clogged up with mud, it doesnt seem to be helping the jeep run cooler much. I just got the aeroforce about two weeks ago and I have had the temp go up to 226 going thru the mountains in Va, but I will say it was a bit muddy. I washed it out after that and havent seen the temp go over 222. Around town driving its 195-210ish, highway its usually 205-220. And nothing cools the trans once it gets up over 195. I tell you one thing running it thru some puddles REALLY cools it off, temps in the 180-195 range. I'll see how it is this weekend after I install my new SPal fan and will be doing a lot of wheeling fri/sat/sun.