Cooling problems

Q

quadepickett

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This is my first post, so I don't really know if I posted it in the right catagory, but here it goes. My Jeep is a 99 Wrangler 4.0 5 speed. The previous owner has converted over to an electric fan. I've replaced the thermostat, upper and lower rad hoses, and even put in a new rad at the end of last summer. It was running fine, never really getting above 190° on the road and 200° on the trail. Then one day out of the blue it started to run around 220°. So naturally the first thing I did was replace my water pump, the problem still persists. I'm stumped, the only thing I can think is that maybe I have a clogged water jacket or something? Thoughts? Opinions? Thanks.

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Running over 220 is normal in hot conditions with the AC on. The temp gauge on the dash on a stock TJ should sit right in the middle (220) or slightly over.

You need to get rid of that electric fan and switch back to the stock setup. That electric fan is a big rookie mistake.

The only thing I can chalk this up to is that maybe with warmer weather it's just running hotter. Running at 190 is too cool anyways, that's not good for the engine to run that cool.
 
That's ac off, and it went into the red about a month ago when I was climbing a hill off-road. It does run cool at night though. I wouldn't mind it if it stayed right at 220°, but I actually overheats if I run the ac or wheel it.

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X2 to Chris's advice, converting the stock OE cooling system to use an electric fan is a downgrade that is also not as reliable. As one who has wheeled in hot desert conditions for 20 years, I'd convert back to the OE system.

Also, the engine and its cooling system was designed to run warmer than 190, it is supposed to run at or very close to 210 degrees. And the engine computer is programmed around that temperature. Running too cool can trick the engine computer into running the air-fuel mixture too rich which reduces power and your mpg. The thermostat absolutely should be a 195 degree thermostat which will bring the temperature up to 210 where the computer will be happiest and the engine will run most efficiently. In states with rigorous smog tests, the engine won't even pass the smog test if it is running cooler than it is supposed to.
 
So I need to go back to the stock setup. But before I go through all that, could I possibly have an air pocket?

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X3 I converted to a flex-a-lite radiator and electric fan shortly after getting my Jeep. For two years I fought running too cool / overheating issues. I tried 6 different electric fan set ups and 4 different trans cooler set ups. I finally went back to a mishimoto radiator and stock fan set up and have not had a single problem since. With the one thermostat, and the mishimoto radiator, it takes longer to get to the 210° mark, but it stays there, and runs great. I would advise against the electric fan unless it is strictly a trail rig, and you don't mind working on it A LOT!


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quadepickett said:
So I need to go back to the stock setup. But before I go through all that, could I possibly have an air pocket?
Click to expand...
Not likely, the 4.0L engine is self-burping. But you could also have a thermostat that is sticking shut. At least try replacing your thermostat with a new 195 degree thermostat which is the factory specified temperature. A Stant SuperStat would be a good choice, most better quality auto parts stores like NAPA carry them. That does not include low-end auto parts stores like Autozone which seldom carries anything that good.

One important note... though they may sound good, avoid any thermostat that describes itself as "fail safe". That design of thermostat won't fail in the stuck closed position but what they do regularly do is get stuck in the open position so the engine can't warm up quickly or completely. Go with a conventional/standard/regular thermostat.

This would be a very good choice... https://www.amazon.com/dp/B000C7YRNM/?tag=wranglerorg-20
 
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quadepickett said:
So I need to go back to the stock setup. But before I go through all that, could I possibly have an air pocket?

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Click to expand...

It's possible, yes. However, to my knowledge, all you have to do to get air pockets out of the cooling system is to let it idle (from a cold start) with the radiator cap off. Let it get up to temperature, and from what I understand, the air bubbles should burp themselves out.

But ultimately, you do want to go back to a stock cooling system setup. Your TJ will be much happier that way.
 
quadepickett said:
Alright, ordered the new thermostat, gonna try that first
Click to expand...
Hopefully you also ordered a paper gasket with it. If not, get one from your local auto parts store. Don't use RTV on the cooling system. Make sure to use a small wire brush on both gasket seating surfaces, both surfaces must be absolutely pristine and totally free of any of the old gasket material or it will leak.
 
quadepickett said:
So no permatex of anything like that?
Click to expand...
Nope, Permatex is RTV. Use a gasket.

P.S. It doesn't take much to seal the cooling system. I had a thermostat go bad years ago on the trail so I had to remove it to stop the engine from overheating. Doing so tore up the old gasket so I cut one out of the cardboard box some military rations came in. That cardboard gasket was totally leak free until I finally got around to installing the replacement thermostat several weeks later.
 
I just used the paper gasket, and nothing else. Just cleaned both surfaces good, and no additional material. No leaks so far, and I did that 20k miles ago.


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