Symptoms
A squeak or 'laughing monkey' chirp from the back of the engine, sometimes with a check-engine light. Left alone, Quadratec warns, OPDA failure can damage the engine.
The fix, step by step
- The OPDA sits in the block where a distributor would be.
- It drives the oil pump and carries the camshaft position sensor, so it must go in with the engine at top dead centre on cylinder 1 and be indexed so the cam sensor stays in sync with the crank.
- Follow the factory service manual's alignment procedure.
- Remove the cam sensor, unbolt the hold-down and lift the old drive out.
- Fit the replacement with a new gasket at the same orientation, then check cam/crank sync with a scan tool.
- ExtremeTerrain says the factory unit's two bronze bushings sit either side of a seal that starves the upper bushing of oil, and the redesigned part moves the seal above the top bushing.
Tools & part numbers
- Socket set
- factory service manual for TDC and indexing
- scan tool to verify cam/crank sync
- new camshaft position sensor (5149034AA for 2005–06 4.0) if the old one is suspect.
Where to buy the parts
Crown Automotive oil pump drive, 2005–06 4.0 L TJExtremeTerrain ↗Amazon ↗
Crown Automotive 5149034AA camshaft position sensor, 2005–06 TJ & Unlimited 4.0Quadratec ↗Amazon ↗
Mopar J3172332 oil pump gasket, 2001–06 TJQuadratec ↗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.