OK, so does the fan, when spun, go more than 1 revolution? Normal would be not to, and it would feel like there is a viscous fluid in the fan, like thick oil or peanut butter, not penetrating oil.

Fan clutch is needed when truck is stopped or moving slow; to make up for slow air flow. Fan clutch is $50 - $100 depending on source. See Hayden 2991 - Severe Duty Fan Clutch | O'Reilly Auto Parts

 

Fan spins as long as I keep turning it by hand. Slight heaviness with each turn but not a lot. It will continue to turn by hand one revolution after another.

Truck radiator is still warm from previous check.

 

I noticed that the O-Reilly part is for a 4.0 liter. I have a 4.6 liter and they do not offer it. Any other sources for a fan clutch? Thanks-

 

When testing fan, the spin for one revolution test is after you stop touching it. So does it coast to a stop quickly, or continue for a whole revolution?

Based on '03 using same water pump as earlier models, it will have same attachment nut. Could be some variation in bolt pattern. Autohausaz.com has a listing of the '03 4.6 liter clutch. But I would want to see that the Hayden 2991 did not fit. It turns same direction, it screws on to same water pump, etc.

 

Fan blade only moves as my hand guides it. When I remove hand from blade it stops and only moves by force of hand. As I spin with hand there is no 'free spin' of blade and a small feel of resistance. Previously I was attempting to spin blade hand over hand at top of blade due to lack of space it will move. I will try to spin it to see how much it will rotate and not go hand over hand to see how far it travels next.

 

If fan stops after release, without going a full revolution, and engine is warmed up, and NOT running, then clutch should be OK. AutohausAZ.com had 4.6 clutch, but sine water pump is same with 97 or 02, Hayden clutch should fit. Well, at least screw on, turn the correct direction, etc.

If not clutch, you may have one or several little things that each make cooling a little less.

 

I see this subject has traveled to another forum too. The fan blade turns ~4" and stops immediately. What other tricks do you suggest?

I went green after all of the Dex Cool picts etc. When I changed the coolant to green the t-stat and expansion cap were replaced. I did add one bottle of Water Wetter at that time. Here is the interesting part that I noticed...

- First month the temperature at hot idle would hover around 206- 208F
- 2nd month the temperature at hot idle hovers around 208- 212F and the weather is cooling off here in N.C. It seemed that the average went up after I removed air from the system.

Is this temperature acceptable?

Thanks-

 

OK. We assume now that fan clutch is still OK.

What temp when you are driving at 40 -50 - 60 mph?

With respect to idle temp, that would be a function of engine heat, AC heat being dumped into radiator from condenser, outside air temp, how fast radiator can get rid of heat, fan speed and cfm moving over radiator, and on and on. There is no doubt, unless you have an oversided cooling system, that temp will increase at idle. 212 seems warm, but there is a reason for coolant and pressure caps, to allow operation when needed above 212. I just don't subscribe to the idea that operation above 212 is standard when running down the road on level ground with no trailer.

When underway, at say 50 mph or better, fior a period of time of say 15 minutes or more, on level ground (plenty of that near Wilmington), I would expect temp in the 190's somewhere. If it is not, what will happen when it is summer time and 100F plus outside? Mine is 178-180 with a 180 stat, and 192-196 with a 195 stat that I put in last night. No such option for D2.

Little things can make a difference:

Six huge driving lights mounted on bumper reduce air flow

One or all of the three radiators for the D2 (AC, oil/tranny cooler, and coolant) clogged with mud, leaves, feathers, trash of any kind. Mine was stuffed with leaves. If you wash them out, don't use a pressure washer, you can damage fins and cores.

Water pump failing - but this is usually accompanied by wobble on the pulley, coolant loss, etc.

Belt route wrong (my PO did that one as well).

Radiator internally restricted with built up calcium deposits (non-distilled water) or dex cool sludge still in lower cross tubes, or PO used stopz leakz and it settled to lower tubes and restricted them. This reduces the number of tubes coolant can pass through, so radiator as a whole can't cool as much. On D1 and early Range Rovers, they had a copper/ brass radiator, which could be un-soldered and rodded out. Taking side tanks off an aluminum and plastic radiator is not always a good idea. But a blocked radiator will show up as hot in one area and much cooler elsewhere. My indy radiator guys says a healthy radiator will be withinn about 10 degrees across the surface. Some radiator shops have a hot citric acid they can circulate to eat off more of the calcium. I had mine rodded and boiled out, big difference.

Cooling fan for AC may have been running earlier, and less now, so there is less cooling at idle. Harder to test on a D2, the ECM decides when to run it. On a D1 they run whenever AC is turned on. My PO added a twist, he had replaced fans, but reversed polarity; they "subtracted" air flow at idle and temp went up. Simple test is a plastic bag held in front of grille - it should pull toward grille.

Of course hoses can be pinched or twisted, one post dealt with the hose from the coolant bottle being twisted, so owner could not fill to proper level.

Trash in the thermostat four metering holes could change the set point of operation, less likely with fresh coolant and stat.

Tranny could be low on fluid, dumping more heat, but if it is too high, there is an idiot light on top right of dash.

Since you don't have heat spikes or coolant loss, HG seems unlikely. Don't think you need to run out and throw money at it, but watch closely (you said it has been creeping up). At next coolant change interval or water pump work, consider getting a radiator shop to flush what you have. There is the old skool flush with white vinegar (does a little) and the remove radiator and lay flat and fill with muriatic acid (not a good idea with aluminum radiators). Shops have a different system.

 

You should consider the In-Line Thermostat Mod. There are lots of threads on this topic to review.

I'm pretty sure I had a bad thermostat from new. About 10 months ago, I had some hose leaks. I changed the thermostat at the same time. I then started to feel it was running hot and changed the radiator and fan clutch. It was still running hot, especially at idle. My truck never over heated but was running hotter that 212 degF as the aux fan was running most of the time. It was alarming how hard the hoses were. I keep expecting them to burst. Occasionally, the pressure cap would dump some coolant overboard. At first I didn't suspect the thermostat because it was new, but everything pointed to the thermostat restricting the flow.

I purchased a scan guage to confirm the temperatures, and yes it was running hotter than 212 deg F. Since I got the Scan Guage I have kept it pretty much plugged in the whole time.

About 7 months ago, I did the in-line Thermostat mod with a 180 deg C chevy thermostat. Since then I have been running between 82 to 90 deg C (179 to 194 deg F), regardless of outside temperature, engine load, etc. The only exception was this summer when it was really hot, I was fully loaded up with gear, and heading up some very long steep hills in BC, the temperature gradually rose to 97 degC. The temp came right back down again on the down hill.

Anyway, I think this mod works well and simplifies the cooling system. There are some that don't agree but I'm pretty happy with it.

If you use the hose adapter with the sight glass it is very easy to tell if you still have some air trapped. I followed the standard bleeding procedure mentioned on this forum. A few days later I still had a bit of air in the sight glass. I then used a coolant pressure test kit to push out the remaining air. That made it very quick and easy to do. No air ever since. It made me wonder how many on this forum still have a bunch of air trapped in the upper hose, but because they dont have a site glass are unaware.

 

I'm thinking the fan clutch is ok. Temperature averaged 206- 208 F at idle for 15 minutes of bumper to bumper when picking up son from school. Drove it on a five mile run trying to time stop lights running 40-50 mph and temperature got down to 203 F. I did not run A.C. today and outside temperature was mid 70's. The lowest temperature I had seen w/in the past few months since the coolant change was 199 F.

I might consider the inline t-stat. Stinks that I just got the t-stat from Atlantic British four months ago but the higher temperatures are starting to stick w/me now that I am constantly looking at the Ultra Gauge.

In regards to the Dex Cool. I did not see a ton of rust on the coolant change when we did the Peak Flush kit test and flushed it out w/a hose. I used distilled water 50-50 mix w/the Peak Global (green). Not sure if I have dex cool sludge or calcium deposits but I do know the previous flush was not done in about 30k miles. The only leak we had w/the Disco was the t-body heater plate had to be replaced. The temp light turned on and I immediately pulled over and added tap water before getting the plate replaced. I was at a construction site that had a hose to water.... no time to shop distilled on that day. Not sure if trash was ever floating in the system.