4L30E, AR25, AR35, A4S 270R

Symptoms:

• Low line pressure
• Burnt clutches
• Soft upshifts
• Delayed Reverse

Cause:
Leakage between the boost valve and sleeve.

Correction:
Sonnax boost valve and sleeve kits are available in three different ratios to restore pressure control in most OE applications.

In GM 4L30-E (AR25 and AR35) units the OE boost valves are made of steel, whereas the sleeves are made out of aluminum. Over time the valve wears against the sleeve and causes boost pressure leakage. The result is low line pressure during boost, with associated burnt clutches. Sonnax boost valve and sleeve kit restores pressure control to the boost circuit.

• Sleeve is made from wear-resistant aluminum and incorporates annular oil passages to distribute boost oil evenly to the valve and reduce side loading
• Valve is hardcoat anodized and includes oil grooves which allow the valve to ride on a film of oil, further reducing wear
• Valve and sleeve are made from the same material to help reduce leakage due to thermal expansion

Kit Contains:

• Valve
• Sleeve

SONNAX Installation Instructions