Just returned from a 1000 mile road trip with no issues to report. Have the 180 degree stat and a new radiator. Ran 186 on the scangauge and only ran up to 190 when pulling a 30 degree grade for about 4 miles with the cruise set at 70. Normal around town temps are 188.6, but it seems to be heating up at idle (stop lights and such) temps rise pretty quick, like up to 203 in the span of a light cycle. If I rev it up to 1500 rpm, temp drops right back down to 188.6 -

question is two fold.

1. is this normal? I get weirded out at anything over 200, so I've never just let it sit to see where it tops out.

2. if not, what's goin' on? fan clutch? fan seems to have the "peanut butter" feel to it. Secondary fan is functioning.

thanks... I'm getting ready to do another 1000 + mile run next week and just looking for peace of mind.

 

Mine started doing this last summer in the 100 degree heat with AC on, and now it's doing it almost whenever it sets idle, but my temps SLOWLY climb, all it takes is a rev or a short drive and it immediately cools down. I expect "air flow" issues (like fan or radiator). I have the same set up as you and have the same 188 running temps. My clutch fan feels great too and I hear it work, but possibly the fan isn't running enough, like it's only 75% effective, in other words failing???...I would like to hear some ideas that others have on this too.

 

I just did some searching on this subject.....very common to have some temp spikes, especially with the 4.6. A lot of people out there have replaced entire cooling systems only to have the same results. I'm not too worried about the temps I sometimes see in my rig, but you may want to search the site to get some ideas of what others have tried/checked since yours climbs so fast. Could be a liner issue

 

If the liner/block failed he would know it. The temp would be overheating. The system itself underperforms when everything is at max efficiency, ie brand new everything. The only things that you can do is get a larger, aftermarket radiator which I have seen priced high as $1,000....switch to a heavy duty viscous fan clutch (cheapest, simplest) rig a controller to the electric/condensor fan to cut on at 180 degrees (my next move) and remove the factory thermostat and splice in the inline type of Tstat. I am certain that the engine is programmed to run hot (fuel & spark) and the factory radiator is too small so you basically have to move more air and more water than the system was originally engineered to do. PS: businesses that remap or recalibrate "chip" the ECU claim that the engine runs cooler after their work is done, so here is even 1-more option, although this rates very high due to the numerous other benefits of tweaking the ECU

 

thanks chubbs... just returned from the second 1000 mile plus trip from Georgia to Virginia in less than 3 weeks... 188.6 with cruise set at 77 most of the trip. Sucker heats up fast once it's at idle, unless I rev it up, then it comes right back down to 188.6. Have replaced the stat with the 180 degree one and installed a new radiator, which brought running temps down from 198 to 188.6, which I'm more than happy with. Any recommendation on the heavy duty fan... probably a write up on the forum for riggin' the condenser fan? It's running very well, with no obvious issues (other than the 3 amigos, which I need to get checked out... was told by the previous owner that it's a wheel sensor that needs to be replaced, but don't know which one.)

 

If the temps are climbing at idle most def a fault with fan clutch (methods for testing existing fan clutch via any search engine). Oreillys sells a HD version made by Hayden or Import Direct. They both have the same part number. Once you replace it you should be good to go. Until the next part goes out, usually a radiator hose fitting, etc. If you have a 2003-04 model you will find a 1-piece fan with clutch integrated. In that case you buy a used, pre-2003 fan and bolt up the new HD viscous clutch. You can get a controller off EBay to splice into the fan loom but unless you live in 100+ climate like me it won't be necessary.

 

... until the next part goes out... exactly replaced all the hoses when I put in the rad... after the first trip, starter took a crap in the parking lot at Target... so I've got a new starter. gonna head in the fan clutch direction... this one in another discussion... Hayden Automotive 2991 Premium Fan Clutch 57 bucks amazon prime

 

Right on, 2991 sounds about right. I see that you do have the 2003 so you will need a $30 used fan from a -2002 recycler or somebody's shelf as those accept the bolt-in clutch. I bought one from a local import recycler and had it shipped in a day. Clean it up like brand new before you move on to step-2. Grease gets caked in all of the holes and grime built up between the outer ring and the blades. A toothbrush and dish soap will maximize its efficiency and prevent corrosion.

 

You can also order a new after market fan from L8 or other vendors if you don't want to deal with a used one. Plastic fans do have a tendency to deteriorate over time and I felt better installing a new one after reading of ones that had failed.
......

 

Dorman 620-112 fan is a direct bolt on to a 99-02 D2 Fan Clutch and 25.00 at Auto Zone.

I'm running the Dorman 620-112 Fan Blade on both my D2's. It's a bit louder vs the OEM fan blade with the ring on it, but I like being able to tell when the clutch is engaged/disengaged. Bolts right on with zero modifications and can be found just about anywhere vs trying to locate an OEM Fan Blade in an emergency.

The 620-112 Fan Blade and the Hayden 2991 (or equal Fan Clutch) do seem to pull more air at idle or slower speeds. During 20-40MPH driving the fan clutch is engaged longer. After 50MPH or 2400RPM it will dis-engage and mostly rely on the air being pushed thru the radiator at speed.

That's where I was seeing the temp climb was during slower speeds, at idle, or on the trail because the OEM setup refused to engage until much later. Here in TX I'd rather have it engaging sooner vs later.

Currently the weather has been more like CA and I've gone from my usual 188-200F range (in traffic, cruising at 75-80MPH, or at idle) to a much lower 175-193F tops. It truly does have a lot to do with the ambient temps.