hmm, I have been running the 203F stat, and pulling heavy loads on long grades, and I can't even get the needle past 1/2 any more at nearly 200k on the bottom end.
The factory FFD shroud is maybe 1", if it's lucky, and it doesn't cover the entire radiator, so there's not even good draw when the fan is on. I'm sure it's just fine for people that don't drive big grades...

Did you compare your rockers to a new one? Maybe, just maybe you're not getting the heat out, but I know that the stock radiator is good for extreme conditions, if it's not clogged anyhow.

Dirty engine, 200k, 203F stat....hmm, oh, I know. It's probably your gear ratio/big tires in combination with AC, rockers, and maybe exhaust. You are running big tires, and if the AC is cranking also, and your rockers aren't opening the valves all of the way, then it's just adding up.

How well does your home-made shroud meet up to the edges of the radiator? I did the same thing, and with many hours of bending, my shroud meets the top and sides pretty tightly, but there's a big gap on the bottom that I was going to seal, but haven't needed to I also have my controller set to kick the electric fan on if the needle barely budges, but I don't think that makes enough difference to matter. Oh, yeah, you put the mech fan back on, so nevermind this paragraph I will say that the mech fan is just adding even more load to the engine on the grades though.

Stock muffler also? I have mine strait piped after the Cat. Best mod ever, I don't even notice the sound unless over 75mph.

I ended up with a free set of BFG ATK02's stock size, and I put them on 1.5 spacers, and I'm loving it. Looks good, stable, and I keep my stock ratio for all of the heavy towing I do. Also keeps the load reasonable since I'm not hauling monster tires. More PSI for the ice also.

Finally, how fast are you driving the grades? If you're pushing 75mph with AC then that's a tremendous load with everything else. I can't budge my needle unloaded at any speed, but I don't even have an AC cooler or fan in front of the radiator, so the airflow is optimal. I drive the big grades in 4th gear at 60mph and 1800 rpm unloaded. Easy on the jeep and never hunts for a gear (with stock tires). If you're unlocking the TC ever on the grades, then that's creating a ton of heat.

Edit: I also have new cams

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05 CRD: H.D.S2 stat,WW Ironrock trilink&LCA's, OX rear,ARB front, 4.10's, ARB bumper, Suncoast,OME 3.5, JBA UCA,rock rails, Moabs&265/75 Duratracs, GDE tunes ,FFD fan,ARP's, 2 micron fuel, new valves,sasquatch battery tray & grid heater, tensioner relocated
Mech fan, VH & AC delete

so my factory rockers seemed to be like new. I checked all of them as I pulled them out and the rocker bearings were tight and the lifters were floating in the rockers pretty well. I did install new rockers of the new design this weekend along with the TB, ARP studs and the water pump.



The jeep only has 95k on it with 50k of that having the EGR blocked and/or GDE Hot tune. I've been over heating even in 55F ambient temps lately, without the A/C even on. It just happened to start doing it in june when temps started to get warm.



My electric fan(Derale 17") is wired into the factory A/C fan harness so I have full control over its low and high speed activation via the ECU tune. Right now I have the low speed set to 96C(205F) and high at 96.5C(206F). The shroud is a home made unit and it is the exact size of the core. I used angle'd aluminum to build a frame which slips tightly between the radiator end tanks and top plates, so it fully fills the 20x20 core opening and is very tightly sealed to make sure the fan gets full pull through the core.





i have 2.5" straight pipe from the cat back. It was one of the first things i did when I bought the jeep 3 years ago.



It can be anywhere from 55mph to 80mph. 7% grades are everywhere around here, my wife drives 3 of them every day on the way to work on back roads. I-80 is a ~3000 ft climb from Salt Lake to where I live at probably a 6% average grade with some nice long 7% sections with a 65 mph speed limit. If I head out into Wyoming or Southern Utah I can see 7% grades with 80mph speed limits.

What was throwing me a bit off was when it did overheat it would take a very long time to cool off. I would pull off the road, the electric fan would be running at full speed, and I would rev the engine up to get the water pump spinning and it would still take a long time to cool down. This was telling me that either there was poor flow, or that the heat was not being removed from the coolant effectively. I just opened up the radiator and it seems to be almost completely clean, all the ports flowed water through them. at this point I am hoping maybe the water pump was slipping or something, otherwise I am at a total loss.

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2006 CRD - GTB2056 turbo by Dieselguy86, Eco Trans Tune, Lift Pump, Week's, HDS Tstat, Racor Filter, ARP's, OME 790's+Top Plate, JBA 2.5", JBA UCA, Moab's+265/75R16, ARB Bull Bar, 4.10's, TrueTracs

hmm, that pretty much blows my additive theory away With all that in mind, it does sound like coolant flow is the problem, but what is slowing it? Did you ever have any of that white goo (or any goo) in your overflow tank?
Can you spin the old water pump prop?
Could your thermostat be binding in the housing? Did it do this prior to the 4J install?

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05 CRD: H.D.S2 stat,WW Ironrock trilink&LCA's, OX rear,ARB front, 4.10's, ARB bumper, Suncoast,OME 3.5, JBA UCA,rock rails, Moabs&265/75 Duratracs, GDE tunes ,FFD fan,ARP's, 2 micron fuel, new valves,sasquatch battery tray & grid heater, tensioner relocated
Mech fan, VH & AC delete

Water pump seemed good, but I also never tried heating it to see if it loosened with thermal expansion or something weird.

No goo I don't believe. Overall my coolant system seems pretty clean. The inside of the radiator was clear with only a slight residue. Water pump and water pump housing were clean. The tstat was just changed out 2 weeks ago and that was clean.

4J tstat was installed in October last year with no issues until June of this year. The overheating got worse more recently. It seems like.

I'm running a flush solution and distilled water through it for a few days to maybe see if the passages in the block itself were plugged up or something.

My mind was wandering a bit yesterday and was wondering maybe the thermistor in the tstat housing was getting heated by the exhaust manifold. It sits an inch or two from the manifold and if I'm climbing these hills at full load for a few minutes I gotta think that a lot of heat is being thrown off the cast manifold. That's a high emissivity surface at a very high temp.

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2006 CRD - GTB2056 turbo by Dieselguy86, Eco Trans Tune, Lift Pump, Week's, HDS Tstat, Racor Filter, ARP's, OME 790's+Top Plate, JBA 2.5", JBA UCA, Moab's+265/75R16, ARB Bull Bar, 4.10's, TrueTracs

you can try to stick temp probe into dash vent , turn heat on FAN on lo speed , drive it and see if temperature is fluctuating ? I'm (worried about head gasket issue)also check small 3/8 rubber hoses going from ls of rad to surge tank and replace 16 psi cap

I'm really wondering now if the a/C condenser is just a major restriction and combined with the fact that I'm at 6500'-10000' with less cooling air density it just need to get hot to shed the heat. It's by far the densest core in the cooling stack and of course sits right in the front blocking the flow to the CAC and radiator.

Maybe I'll ask gde what they experienced when they were extreme testing these thing for their tunes. I seem to remember them saying that when they were testing at Davis dam or whatever, the Jeep would heat up to the point where the ecu would cut fuelling and they would end up at like 40 mph.

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2006 CRD - GTB2056 turbo by Dieselguy86, Eco Trans Tune, Lift Pump, Week's, HDS Tstat, Racor Filter, ARP's, OME 790's+Top Plate, JBA 2.5", JBA UCA, Moab's+265/75R16, ARB Bull Bar, 4.10's, TrueTracs

Maybe its the transmission cooler?

The trans cooler makes up the lower portion of the ac condensor. Climbing mountains the way you are, the trans must be getting hot too. And that heat also has to get transferred through the stack.

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U.S. Army Retired

Well it seems to be getting a bit better after running the prestone flush/distilled water for a few days. The temps were rock solid driving at 50+, not even getting hot enough to trip the fan at 97c. However, I climbed up to guardsman's pass which a very windy, very steep climb(10%+ sometimes) from about 5000 ft to 9500 ft And it did get up to 107 when I had the AC on. Turned the AC off and it came back down very slowly. Turned it back on and it went back up. This was in 65f temps at the bottom and 50f by the top.

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2006 CRD - GTB2056 turbo by Dieselguy86, Eco Trans Tune, Lift Pump, Week's, HDS Tstat, Racor Filter, ARP's, OME 790's+Top Plate, JBA 2.5", JBA UCA, Moab's+265/75R16, ARB Bull Bar, 4.10's, TrueTracs

well that is good news that not overheating anymore , i see people removing mechanical fan from there unit for a reason they think they running too cool , but i guess you do some hard pulling uphill with your rig , but if it does it again i say take this seriously because running this motor HOT can lead to a disaster

that is some extreme elevation. I keep mine cool towing up major grades, but not like the ones that you're talking about. You might have to do what I do when pulling 6500 lbs up a grade, and go about 49 mph with TC locked, 1800 rpms roughly. Beyond that there's a lot more load. I think your tires are adding a lot of load too, slight difference in ratio, and a lot of weight. Wouldn't be much a problem, but 6500-10k, that's pretty extreme.
Oh, what about your self tune ventures? If you're running a self modified tune, have you tried a plain stock or GDE tune with regards to temp?

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05 CRD: H.D.S2 stat,WW Ironrock trilink&LCA's, OX rear,ARB front, 4.10's, ARB bumper, Suncoast,OME 3.5, JBA UCA,rock rails, Moabs&265/75 Duratracs, GDE tunes ,FFD fan,ARP's, 2 micron fuel, new valves,sasquatch battery tray & grid heater, tensioner relocated
Mech fan, VH & AC delete

It is a steep climb, but its slow, like 25mph or less in 2nd or 3rd gear since its so curvy. And like it said, it was a pretty cool day at only 65 max. It it had been mid summer things would have been bad.

I had flashed back to stock a while ago and it didnt fix anything, so I actually wrote a tune specifically to turn my electric fan on high speed at lower temps and cut fueling more dramatically as the coolant temps rose to prevent too much over heating. I went back to my full power tune a few days ago to see if i can get it to break and so far its been good.

I am a little pissed because the first thing I did when I started having these issues was bring it in to get flushed at a shop. it didnt do a thing, so I wrote that off and moved on to the next thing. I am actually wondering if they either didnt do the flush at all or they didnt get it hot enough to open the tstat and flush the radiator. Clearly the issue was not getting the heat from the engine into the coolant, but getting heat from the coolant into the air.

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2006 CRD - GTB2056 turbo by Dieselguy86, Eco Trans Tune, Lift Pump, Week's, HDS Tstat, Racor Filter, ARP's, OME 790's+Top Plate, JBA 2.5", JBA UCA, Moab's+265/75R16, ARB Bull Bar, 4.10's, TrueTracs

At 25mph your TC is unlocked and creating a lot of heat with little airflow throught the grille. A long slow climb up a hille like that and things will get real hot really quick.

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U.S. Army Retired

X2, I see this a lot with where I hunt, log, and live. But the worst are the long grades where I'm going like 10 mph, I have less trouble at 25, but then again, I tow 5000+ lbs in these conditions all of the time with no trouble since I made all of my mods. I'm fairly certain that my e-fan actually cools better, after having driven several CRD's up long grades, but I don't have any data to back that up. Though, I think the extra load the mech fan adds is considerable, and why I cool better.

I would definitely try some stock tires for a comparison if you can without spending much. If there's a lot of speed up after each corner, then the extra mass is going to work against you.

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05 CRD: H.D.S2 stat,WW Ironrock trilink&LCA's, OX rear,ARB front, 4.10's, ARB bumper, Suncoast,OME 3.5, JBA UCA,rock rails, Moabs&265/75 Duratracs, GDE tunes ,FFD fan,ARP's, 2 micron fuel, new valves,sasquatch battery tray & grid heater, tensioner relocated
Mech fan, VH & AC delete

Something you may have already considered, is at those elevations, you may have lower ambient air temps, but you also have much lower ambient air density. The air going through your stack is cooler going in, but the actual mass (and ability to absorb the heat from your cooling stack) is just a fraction of "normal" and increasingly reduced the higher you go.

About the only way to compensate for this is to increase the area of the heat transfer media, either by size or by design, or by increasing the efficiency of the heat transfer media, which, it sounds like, you are already doing.

I assume you have already used either a pressure washer or steam cleaner on the air-side fins of all 4 coolers in the stack to remove all dust-small rocks-bugs, etc that block air flow?

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'06 Lbrty Sprt CRD 150K

Sasquatch
DSS Turbo
CAT-elimntr
Weeks Stg1&2 EGRfix
PV-200
BLING
vent gauges

IDParts
head
cams
rockers
Timing set
ARP studs
eTn1 GX2123 5v GPs

YETI Custom Tune
Flowmaster 8325508
Carter P76611M
GM 12611872
Hayden 2986
GM 15976889
PATC Custom Billet
2010 Ram Hemi Trans
Sonnax 44957
Transgo kit
Cooper 51770

well chasing overheat issues , can be challenging , when i was on shop floor ( TRUCK ENGINES) if all the above suggestions where exhausted , at the end we didn't have choice then go to disassembly , pull cylinder head , if no problem with head and gasket , we would pull cylinder liners too just check everting , liner protozoon etc it can be done you just need to make up your mind and go to work all night , oh that was when i was young and didn't mind working night shift LOL