Valve Seat Popped Out of Engine Block
The valve seat has popped out of the engine block. How can this be repaired?
This failure usually occurs due to an overheating issue. Overheating is a cause of engine failure from an engine component material that has distorted beyond a specific yield point. The yield point is the limit of a material at which it can be exposed to heat or mechanical stress and still return to its original size and chemical composition. Overheating occurs from causes such as a lean air-fuel mixture, use of improper fuels, dirt and/or debris buildup on cooling fins, damaged cooling system components, reduction in cooling air, over speeding, or an improper engine enclosure.
Valve seat inserts are installed in the cylinder block using a press fit. A press fit is a method of attaching two mating components where one component is pressed into a machined hole having a slightly smaller diameter than the component inserted. Valve seat inserts are commonly .003” - .005” larger than the machined hole in the cylinder block. The pressed fit retains the valve seat insert in position with a constant force. This force is necessary as small engine have significant responses to heat generated in the combustion process. If the cylinder block expands past the yield point, the force is not present to keep the valve seat in place.
In some cases the valve seat can be peened back into place. However, there is no guarantee this type of repair will add significantly to the engine's life. To determine if this procedure may work in your situation, please consult a Briggs & Stratton Authorized Dealer. This Service Dealer has all the information relating to Briggs & Stratton warranty information, engines, short blocks, parts, prices, service, specifications, proper fit, etc. To find our "Best-of-Class" dealerships, look for our Master Sales & Service Dealers (MSSD).
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