99A8620 | Genuine Horton® DM Engine Cooling Fan Clutch

Part number is designed as a direct OEM component and replacement for heavy-duty commercial truck platforms:

• International / Navistar Trucks: ProStar, LT Series, LoneStar, WorkStar, 8600, 9900i series.

• Freightliner Trucks: Cascadia, Columbia, Century Class, Coronado.

• Kenworth & Peterbilt Trucks: Kenworth T660, T800, W900; Peterbilt 386, 388, 389.

• Engine Compatibility: Cummins ISX15 / X15, Detroit Diesel DD13 / DD15, International MaxxForce 13 / N13, and Caterpillar C13 / C15 diesel engines.

1. What is it?

Part is an OEM front-engine fan drive mounted between the water pump pulley and the cooling fan blade. It dynamically connects and disconnects the radiator fan based on real-time engine coolant temperatures and compressed air signals from the solenoid valve.

2. Core Functions & Features

• Fuel & Horsepower Conservation: Disengages the fan when engine cooling is not required, reducing parasitic horsepower drag by up to 50 HP and saving significant fuel.

• DM Advantage® Technology: Features heavy-duty dual-row angular contact bearings and a high-grade friction liner for extended service life under extreme engine bay heat.

• Fail-Safe Operation: Spring-engages the fan if pneumatic air pressure is lost, ensuring the engine continues to receive cooling air and preventing catastrophic overheating.

• Pneumatic Actuation: Responds rapidly to ECM temperature thresholds via pneumatic pressure from the air brake/accessory reservoir system.

1. Engine Overheating Under Heavy Load

• Symptom: Coolant temperatures spike rapidly while climbing grades, pulling heavy loads, or idling in warm weather.

• Cause: The fan clutch fails to engage because of a worn friction plate, low air pressure, a failed solenoid valve, or leaking internal seals.

2. Fan Runs Continuously (Stuck Engaged)

• Symptom: Loud fan roar at all speeds, noticeable loss of engine horsepower, and reduced fuel efficiency.

• Cause: Mechanical seizure, broken internal springs, or a loss of supply air (spring-engaged fail-safe mode).

3. Excessive Noise, Squealing, or Grinding

• Symptom: Loud metallic grinding, squealing, or rumbling noises coming from the front of the engine housing.

• Cause: Worn or dry internal pulley bearings, failing clutch pack linings, or belt misalignments.

4. Visible Friction Dust, Oil Contamination, or Play

• Symptom: Black friction dust around the clutch face, grease leaking from the hub, or physical play when rocking the fan blades.

• Cause: Severe thermal degradation of the friction material, compromised bearing seals, or worn hub shafts.