Jeep sounds completely different after cooling system overhaul

04 LJ

🇺🇸 JEEP 🇺🇸
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Winterville, NC
So I’ve had many 4.0 Jeeps (not all Wranglers) and for the most part, they have all sounded the same. That was the case for my LJ too until this evening when I took it out for its maiden drive after completely overhauling the cooling system. It’s very bizarre and I’m not sure how to explain it other than it seems way louder during acceleration. Like the more I accelerate, the more of a “whoosh” sound I hear. I feel like I hear more whooshing than I do engine now which it definitely didn’t do last year before the overhaul. Since it gets louder as I accelerate I can only assume it’s the fan moving more air but it’s the same fan I had before, just with a new clutch...? I know this sounds weird but I know how my Jeep sounded before and how it sounds now. All gauges were where they needed to be, just FYI. Speaking of gauges, I was somewhat disappointed to see the Jeep running at 210 degrees after the complete overhaul. I thought I would at least get a few degrees from it.

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If you put a 210 thermostat in it should stick to that temp is my understanding.

Mine after a a cooling system overhaul did the same thing. It's got much louder of a fan noise.
 
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Mine did the same after installing the new fan clutch. You could spin the old one with one finger, at any time. I just figured the new fan clutch has way more resistance, and therefore spinning the fan way more, and faster, making more noise. Yeah, that’s it. Makes gobs more horsepower than before. If I paint the fan red . . .
 
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If you put a 210 thermostat in it should stick to that temp is my understanding.

Mine after a a cooling system overhaul did the same thing. It's got much louder of a fan noise.
I put a 195 Stant Superstat in it. Part # 45359. Concerns me that it’s staying at 210.

I’ve never overhauled the cooling system in any of my Jeeps before. Perhaps it’s the brand new clutch spinning the fan faster than the old clutch did?
 
A 195* t-stat is what you need. That temp reading is normal for your 4.0

I agree with pagrey, the new clutch is making a difference. Mine did that too.
 
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I've read somewhere on here that the actual numbers on the guages may not be real on the newer TJs. Specifically the oil pressure guage is controlled by the computer to always read in the center unless there is a problem. The oil pressure in my 98 drops way down to less than 20 at idle after warmed up. I believe the newer computers don't let that happen. Could temp be the same way? Good always = 210, bad = different?
 
No, that's normal for it to run at 210, regardless of how new the cooling system is.

You want it to run at that temperature, as that temperature is the optimal temperature for the PCM to be running at. If it was running too low, you'd actually be getting worse performance from your engine.

As for oil pressure, ignore that gauge entirely. The stock oil pressure gauge is basically useless.
 
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Might need to burp it some more to get your temp back down. Seems like I remember burping mine every day for a week afterwards. Lot less fluctuation now.
So Thursday after I finished the install I filled it, ran it in the garage until it got to temp and then I shut it off. Once it cooled, I opened the cap, heard some gurgling, added more fluid, and repeated. I’ve done this several times now until the fluid under th cap is still full after running it. Should I be burping it another way or doing something different?

Just FYI, the new overflow was filled to the full mark and hasn’t moved a MM. Not even after my road test last night.
 
I've read somewhere on here that the actual numbers on the guages may not be real on the newer TJs. Specifically the oil pressure guage is controlled by the computer to always read in the center unless there is a problem. The oil pressure in my 98 drops way down to less than 20 at idle after warmed up. I believe the newer computers don't let that happen. Could temp be the same way? Good always = 210, bad = different?
Interesting. I’ve never heard this before. Seems about like something DC would do.
 
So Thursday after I finished the install I filled it, ran it in the garage until it got to temp and then I shut it off. Once it cooled, I opened the cap, heard some gurgling, added more fluid, and repeated. I’ve done this several times now until the fluid under th cap is still full after running it. Should I be burping it another way or doing something different?

Just FYI, the new overflow was filled to the full mark and hasn’t moved a MM. Not even after my road test last night.
I had air bubbles in my heater hoses, I think. There’s probably quite a few other little places where air can get trapped as well throughout the system. I would start it up, with the cap off, and start moving the hoses around with my hand. There’s probably a more professional way to do it, as I’m not a mechanic. But, with all the correct parts in place, it’s rare my temperature fluctuates much at all once it gets warmed up.
 
That's the exact temp my runs at and I was concerned at first, but then got educated that's the correct temp it sounds run at.

Great heat in the winter tho..

I Purge air by putting the front up on car ramps and doing the same. Dunno if really helps but seems to.

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I put a 195 Stant Superstat in it. Part # 45359. Concerns me that it’s staying at 210.

I’ve never overhauled the cooling system in any of my Jeeps before. Perhaps it’s the brand new clutch spinning the fan faster than the old clutch did?
Mine runs exactly at 210 when I checked with a scan tool it’s actually 204
 
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Agreed, the sound the OP is hearing is almost certainly the fan moving air. The new fan clutch probably engages tighter than the old one, spinning the fan faster at given engine rpms than the old one. It also may engage the fan more frequently than the old one.

The rated temperature for a thermostat is the temperature at which it will begin to open. Typically it will not be fully open until 12-15 deg above the rated temperature (as per Stant's website), hence the commonly seen 210 operating temperature.

And yes, since the advent of OBDii around 1996, I don't think any instrument panel gauges on any vehicle get a signal directly from a sensor. All sensors send their signals to the PCM, which positions the gauge needles where it has been programmed to do so.
 
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The same?
Running up to Temp,. Let cool, release air.

Or I get lazy and leave the cap off and run it at advance rpms for about 30-40 seconds.. I do that there times and watch the air burp out.

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Running up to Temp,. Let cool, release air.

Or I get lazy and leave the cap off and run it at advance rpms for about 30-40 seconds.. I do that there times and watch the air burp out.

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Gotcha. I cranked it today with the cap off and before I could get back around to the front the damn coolant was bubbling out the neck.