Hello all and I’m sorry to bother with this topic. As you all know it’s summer and hotter than **** in NM. I have a 96 4.0 4x4 and it’s having a hard time keeping up with the heat. The list of parts goes as follows……
headgasket, Clearwater head, CSF radiator(stock size), 190 tstat, 97+ new efan, new shroud, waterpump, rad hoses, heater core, overflow line to the bottle, new housing for tstat, new belt and the list goes on. You name it, it’s been replaced. The gauge is indeed accurate and so far the highest I’ve seen it go was the line right before the red. I’ve sat and idled it for about 2 hours last Monday and it held its temp ar about 220 or so and I’m thinking maybe the fan clutch is no good? It currently has a 4cyl fan clutch from napa(I don’t remember the PN) as I was told that it does better than the 4.0 fan clutch but I went ahead and ordered a heavy duty ZJ one anyways to try and eliminate that. Any insight would be appreciated. There’s no lift or anything of the sort, stock height, stock suspension, stock body and everything. Also it did come with the towing package from the factory and does currently have a new trans cooler and lines.

 

Does your efan kick in properly? Don't know about the 4cyl vs 6 fan clutch. 220 at a long idle in hot weather, hood closed doesn't sound like it's overheating. You can test the fan clutch easily enough.

 

No 220 was fine at idle, driving is when it heats up. Yes the efan kicks on with the A/C but does not kick on on its own, it is on a switch and I have been driving it with the AC on. I don’t think it makes a difference but all AC components are new as well, all the way from the condenser to the evap/heater core. I just put in the new efan yesterday and it helped a bit but still runs hot.

 

I'd think that fanclutch already be replaced..

I once accidently ( wrong part delivered) put a ZJ clutch in. It made more roar but it had like 2mm clearances from the radiator which was unsettlimg to drive with so just replaced it with an XJ one and it was fine.

Each have typical things to check more for when running hot driving versus idle-

What mix are you using?
OEM thermostat?

 

Once I got home today I tested it, right after shutoff I went out and spun the fan by hand and got little to no resistance, almost like it had just a slight drag on it. I’ve heard of the slight power loss and the noise but honestly I don’t care about either haha. It currently has a 190 stant I believe. For whatever reason I kept blowing through tstats, probably 2-3 in a year. I usually use the stuff you mix on your own, 50/50 with distilled water.

 

I only trust the OEM thermostats. A thermostat that doesn't open properly causes issues, both at idle but more so when driving.

Was your coolant dirty/milky at all?
No air in system?
Anything blocking the flow through your new radiator?
Waterpump correct rotation? (just checking all the things here)


Replace the fanclutch, get an OEM thermostat and I think that should solve the issue. The whole cooling system isn't very complicated so with the above you pretty much overhauled the whole thing and I'd be surprised if the running hot persists

 

You mentioned a new trans cooler. Was that just an an exact replacement of the OEM auxiliary trans cooler (the small one that sits along the bottom of the radiator) or an aftermarket one that covers up a lot of the radiator??

 

I may have to try the OEM thermostat, as far as I know the one in there now is working like it should, in the mornings the Jeep will hold its temp right at 210, if not a little below just fine. It’s just when you run the AC in the afternoon but in the afternoon it’s 100 degrees out haha. Oil is not milky, coolant is not milt and as far as I know there’s no air in the system. No the cooling system is not complicated at all on these which is why it’s bugging me so much that I’ve had so many issues with it! I wouldn’t think the water pump is spinning the wrong way but who knows.

 

It’s an OEM placement cooler, the smaller one that actually bolts up to front crossmeembee and runs along the bottom of the radiator.

 

Alrighty so I got the new fan clutch in and ensured efan is working properly. No dice….without ac it’ll stay down in the 210-20 range which is just fine but with ac it’ll kinda hold that and then it just seems to let ago. Again, Efan is working correctly, as well as literally everything else being new. I’m at a loss haha

 

"as far as I know there’s no air in the system. "

Make sure
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any tips to ensure it’s bled? I’ve heard these can be a ***** to bleed air out of.

 

Running hot while moving is usually related to the radiator or water pump. What's the age and specs on those, especially the radiator? Regular ol' parts store single-row radiators often time work better than the fancy, multi-row models of years past. Improvements in radiator manufacturing, especially thinner walls and bigger tubes, have really improved their performance.

Depending on how cold it get where you live in the winter, you can reduce the amount of anti-freeze, which will increase the heat transfer rate. 40/60 or even 30/70. Still need to maintain the corrosion resistance...

You could try a product like

https://www.summitracing.com/parts/red-80204

or

https://www.summitracing.com/parts/rpo-01600

 

Specifically I have the CSF 2670 dual row radiator that I put in on march of this year. Specifically the water pump is GMB 1101080P that I installed February of last year. Since then this things had maybe 10k miles put on it and they’ve not been hard miles. 0 off-road, all city driving and one trip from ABQ, NM to Phoenix. I’d rather not use additives as I feel I shouldn’t have to but apparently not. Also this is all while the AC is on, when AC is off and efan running its holds 210-20 no problem. Just tested that.

 

There's your problem... Brass/copper radiators aren't as efficient as aluminum radiators.