you did not provide engine models. In the past five years, I have not observed complete engine failure with any Briggs Vtwin.

I assume the 27 hp is a 44xxxx or 49xxxx model series. Older engines have a few sticking valve problems when using ethanol fuel. I have not observed this problem when owners use the fuel preserver. Valve covers tend to have small oil seepage if equipped with valve cover gaskets. The newer style uses sealant and is usually leak free. Avoid the models that are equipped with the flat air filter due to dirt bypassing the filter. The newer models have an oval filter that seals very well.

On Vanguards, I have not seen any sticking valves. Oil seepage around the valve covers is observed on older models with high hours. Air filters seal ok. The blower cover is more difficult to remove / install than the other engine.