The ability to spin as a higher speed at idle of slow speed is the advantage of an electric fan. At slow speed is when many vehicles have cooling problems as the fan slows down with the engine RPM.
Getting back to you first post, It is vert common for the D stock fan clutch to cause a lot of fan noise at start up and you swear that the engine is rev'ing fast and you have now power. It is a combination of the clutch locking up a little and the design if the fan blades. A lot of D owner's complained about the noise. There is a TSD that tells the dealers to tell customers that the noisy fan is normal. An alternate the V10 fan. There is a TSB for engine runnig hot, to replace the fan and clutch with the V10 fan. I got it while under wartranty. It is very quiet even when locked up. Here is the TSB and the parts if you want to do it.. The shroud is not necessary:
Engine Overheats in High Ambient Temperatures
Source: Chrysler TSB 07-07-98
Models: 1998 -1999 (DN) Durango
Symptom/Condition: Some Durangos may experience a high engine temperature condition [temperatures greater than 116°C (240°F)] when the vehicle is operated in stop-and-go traffic with ambient temperatures exceeding 32°C. (90°F.). The result from the high engine temperature may cause the following:
• Engine Temperature Gauge To Read Higher Than Normal
• Check Gauge Lamp To Illuminate
• Warning Chime To Sound
• Vehicles Equipped With Air Conditioning May Have The A/C System Disabled
NOTE: The powertrain control module (PCM) is designed to disable the air conditioning systems when engine temperatures exceed a predetermined value and/or the A/C high side pressure exceeds 470 P.S.I. ± 20 P.S.I.. This is a normal condition designed to protect the engine from overheating and from damaging the A/C compressor. Once the engine temperature and/or A/C high side pressure has lowered, the PCM will turn the air conditioning system on.
1. Examine the vehicle’s cooling system for proper operation. The DRB lilt can be used to ensure that the engine temperature does not exceed 99° C. (210° F.) during normal operating conditions. If the engine temperature exceeds 99° C. (210° F.) during normal operating conditions, the cooling system must be inspected and repaired. Refer to the 1999 Durango Service Manual (Publication No. 81-37091 16), pages 7-9 through 7-20 for information regarding Cooling System Diagnosis And Testing.
NOTE: This bulletin addresses engine overheat conditiones that occur only in stop-and-go traffic with temperatures exceeding 32°C. (90°F.).
2. If the vehicle’s cooling system is operating normally and the customer identifies that the vehicle exhibited the previously stated SYMPTOM/CONDITION, perform the Repair Procedure.
(1) 52027709 Fan, Cooling
(1) 52029767AA Drive, Fan
(1) (AR) 52029012AC Shroud, Fan, Four Wheel Drive
(1) (AR) 52028614AB Shroud, Fan, Two Wheel Drive
This bulletin involves installing a revised fan and fan drive and in some cases, installing a new fan shroud.
1. Disconnect and isolate the battery negative cable.
2. The thermal viscous fan drive/fan blade assembly is attached (threaded) to the water pump hub shaft. Remove the fan blade/viscous fan drive assembly from the water pump by turning the attaching nut counterclockwise as viewed from the front of the vehicle. Threads on the viscous fan drive are RIGHT HANDED. A Snap-on 36mm fan wrench (Snap-on number SP346 from Cummins Diesel Tool Set (Snap on number 2017DSP)) can be used. The water pump pulley can be held in place by one of the two following methods based upon whether the water pump pulley is pressed onto the water pump or held in place with four attachment bolts.
• Pressed-On Water Pump Pulley: The water pump pulley can be held in place by using Spanner Wrench (Special Tool 6958) and Adapter Pins (Special Tool 8346).
• Bolt-On Water Pump Pulley: Place a bar or screwdriver between the water pump pulley bolts to prevent the pulley from rotating.
3. Remove the four fan shroud bolts securing the shroud to the radiator.
4. Remove the fan shroud and fan blade/viscous fan drive assembly as a complete unit from the vehicle.
5. Remove the four fan blade-to-viscous fan drive attachment bolts.
6. Inspect the fan shroud for uniformity where the fan blade opening is. The circumference of the fan blade opening should not have any deformations. If the fan blade opening is deformed, replace the fan shroud (see Parts Required section)
7. To allow for adjustment of the fan shroud, drill the upper fan shroud attachment holes to 15 mm (0.59 in.).
8. Attach the new fan blade p/n 52027709 to the new viscous fan drive p/n 52029767AA using the four bolts removed from the old assembly. Tighten the bolts to 23 N.m (17 ft. lbs.).
9. Position the fan shroud and fan blade/viscous fan drive assembly to vehicle as a complete unit.
10. Install the fan shroud onto the radiator leaving the attachment bolts loose.
11. Install the fan blade/viscous fan drive assembly onto the water pump shaft. Tighten the nut to 27 N.m (20 ft. lbs.).
12. Rotate the fan by hand to ensure no contact between the fan blade and the fan shroud. Adjust the position of the fan shroud so that the clearance between the fan blades and the fan shroud are equal throughout the circumference of the shroud and there is 8 mm (0.30 in.) of clearance between the fan blades and the fan shroud. The fan shroud attachment holes can be enlarged even further if necessary to achieve proper clearance as long as the fan shroud bolts continue to have an adequate clamping surface. Tighten the fan shroud bolts.
13. Connect the battery negative cable and reset the clock.
14. Start the engine. Firmly apply the service brakes and put the transmission into "D". Perform a "brake torque" check to ensure that the engine motion does not cause the fan blades to come in contact with the fan shroud.
15. Perform the same test but with the transmission in "R".
16. If the fan blades came in contact with the fan shroud at any time during the previous two tests, readjust the fan shroud as necessary.
Viscous Fan Drive Service:
Source: Chrysler TSB 07-09-98
Models: 1998 - 1999 (AB) Ram Van
1998 - 1999 (AN) Dakota
1998 - 1999 (BR/BE) Ram Truck
1998 (ZJ) Grand Cherokee
1998 (ZG) Grand Cherokee (International Market)
NOTE: This bulletin applies to vehicles equipped with a 3.9L, 5.2L or 5.9L gasoline engine built after January 5, 1998 (MDH 0105XX).
Discussion: Vehicles built after January 5,1998 have the water pump pulley pressed onto the water pump hub shaft. As in previous models, the viscous fan drive is threaded onto the water pump hub shaft. Because the pulley is pressed onto the hub shaft, viscous fan drive removal/installation procedures are unique.
The fan/viscous fan drive assembly can be removed or installed from the water pump by turning the mounting nut. To remove the fan/viscous fan drive assembly, turn the nut counterclockwise as viewed from the front. To install the fan/viscous fan drive assembly, turn the nut clockwise as viewed from the front. Threads on the viscous fan drive are RIGHT-HANDED. Snap-On 36 mm Fan Wrench (number SP346 from Snap-On Cummins Diesel Tool Set number 2017DSP) can be used to remove/install the fan drive assembly on gasoline engines. To hold the water pump pulley from rotating, place Miller Special Tool 6958 Spanner Wrench onto the water pump pulley with adapter pins 8346 inserted into the holes on the pulley, see Figure 1.
NOTE: Replacement water pump P/N 53021018 has been superseded to P/N 53021018AB which will have the pulley pressed onto the water pump hub shaft. Water pump P/N 53021018 was used to service 1993 - 1998 3.9L/5.2L/5.9L (gasoline engines) water pumps.
99 Durango 5.9, FT 4x4, IP stage III w/ K&N air hat, M1, MOPAR PCM, Fastman TB, 1.7 RR, JBA headers, Borla cat back, Martin Saine valve body, Hotchkis swaybars, Blistein shocks, lowered 2" Black Rhino Kenya wheels, 246. 7 RWHP, 319 TQ