Whenever the pressure drop across the lubricating oil filter exceeds 689 kPa [100 psi], the oil filter bypass valve opens and allows lubricating oil to bypass the lubricating oil filter.

This condition can occur during cold ambient (cold lubricating oil) engine start ups.

The purpose of the bypass valve is to maintain lubricating oil flow to the engine and to prevent an oil filter collapse.

Loosen the retaining plug with a 5/16-inch hexagon allen wrench.

Remove the retaining plug (1), the plunger (2), spring (3), and poppet valve (4) from the lubricating oil cooler transfer housing (5).

If the poppet valve sticks in the housing, it can be removed with the aid of a bent wire or by using your finger.

WARNING  When using solvents, acids, or alkaline materials for cleaning, follow the manufacturer's recommendations for use. Wear goggles and protective clothing to reduce the possibility of personal injury.

WARNING  Wear appropriate eye and face protection when using compressed air. Flying debris and dirt can cause personal injury.

Clean the poppet valve spring, plunger, and retaining plug with solvent and dry with compressed air.

Inspect the o-ring on the retaining plug for cuts or tears. Replace the o-ring if damaged.

Inspect the teflon o-ring on the poppet valve for wear, cuts, or tears. Replace the complete poppet valve if there is any damage.

Use the valve spring tester, Part Number 3375182, to measure the spring force.

Compress the spring to a height of 59.18 mm [2.330 in]. The force required to compress the spring to the specified height must be:

Compression Spring Force

After lubricating all pieces and the o-ring seal, install the poppet valve (4), spring (3), and plug (1) into the lubricating oil cooler transfer housing (5).

Tighten the retaining plug.