In Jatco/Nissan RE5R05A units, the cooler bypass valve is designed to allow excess oil to bypass the cooler circuit when required. However, if there is excessive wear in the bore, it can allow converter and/or lube circuit leakage and prevent the valve from stroking to the bypass position if needed. This can result in increased ATF temperature causing bushing and sealing failure, planetary destruction and converter or part overheating and damage. Severe wear prevents the valve from stroking properly, simulating a cooler restriction and increasing converter charge pressure. Sonnax oversized cooler bypass valve kit 63741-07K allows the bore to be refurbished to restore hydraulic integrity and has multiple design improvements to prevent reoccurrence of the failure.

• Hardcoat anodized aluminum valve combats premature wear
• Annular grooves added to hydraulically center the valve in the bore to prevent wear
• The lengthened valve provides over twice as much sealing contact area as OE
• Stability of the valve in the bore is greatly increased due to the critical spool diameter being over twice as long as OE