Symptoms
A chirping 'laughing monkey' noise from the top of the engine, most often on 2005–06 4.0s. Left alone, Dorman says the center shaft can seize and destroy the cam bearing, and Quadratec warns failure can damage the engine.
The fix, step by step
- The OPDA sits where a distributor would be and carries the camshaft position sensor, so its position matters.
- Following the factory service manual, bring cylinder 1 to top dead center on the compression stroke, mark the sensor's orientation, disconnect it, remove the hold-down clamp and lift the old drive out.
- Install the replacement in the same orientation so it engages the oil pump, then refit the sensor and complete the manual's synchronization check.
- Inspect the old unit's upper bushing and gear for wear, and change the oil and filter afterwards in case debris reached it.
- Dorman's version uses a self-lubricating upper bushing; Crown's moves the seal above the upper bushing.
Tools & part numbers
- Socket set
- factory service manual (TDC and sync procedure)
- paint marker
- scan tool if available.
Where to buy the parts
Crown Automotive 53010624AC oil pump drive assembly, 05–06 TJ 4.0LQuadratec ↗Amazon ↗
Crown Automotive 53010615AB oil pump drive, 00–04 TJ 4.0LQuadratec ↗Amazon ↗
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Rated for a competent home mechanic with a decent tool kit. Confirm torque figures, fluids and procedures against the factory service manual for your VIN, support the truck on stands rather than a jack, and work at your own risk (disclaimer). Some parts links are affiliate links, which pay us a small commission at no cost to you.