During a generator package overhaul in our workshop, our engineers encountered an issue that could have resulted in significant costs for our client.
As part of the scope, we removed and dismantled the cylinder heads, including the valve seats. The process for seat removal involved heating each cylinder head to 220°C in an oven, then removing the valve seat and installing a new one before the cylinder head cooled. Unfortunately, this process didn’t allow time to measure the valve seat bores.
With aluminium cylinder heads, the new seats required a higher interference fit than cast iron heads. We knew this could be a critical issue based on our experience with valve seats dropping on other engines.
To ensure reliability, we tested the new valve seats by allowing the cylinder heads to cool and then re-heating them to 200°C. This inspection revealed too much movement in the valve seats, prompting their removal for oversized replacements to achieve the correct interference fit.
The challenge was that the OEM didn’t offer oversized valve seats, and their recommendation was to replace the cylinder heads at a cost of around £1,500 each.
Instead, we opted to have oversized valve seats specially manufactured by a trusted specialist, saving significant costs and enabling us to complete the overhaul efficiently.
This is an example of a genset we have been working on recently. More on this one to follow…
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