Motorcycles and Oil Leaking
How irritating are oil leaks? Even a small oil leak can be disproportionately annoying. Motorcycles can and will leak oil; it's often what some of them do best. In an ideal world it wouldn't happen but age, wear and tear, overuse, inactivity and abuse often take their collective toll. Some motorcycles leak oil because of inherent design faults, poor quality components or insufficient gasket faces but in general the vast majority of the modern motorcycles available in Thailand don't tend to fall into this category.If we talking about motorcycles that are famous for leaking oil we often directly refer to British, German and Indian made motorcycles, and for the budget motorcycle most Thai motorcyclists have not much good to say about Chinese motorcycles if it comes to oil leaking... Japanese motorcycles, despite what you might hear and read elsewhere, can and does leak oil...
The good news is that generally the fixes are relatively simple and straightforward. The supply of parts for even older motorcycles is surprisingly good and we found it simple and easy to obtain a seal for every leak we ever identified.
There really is no genuine reason to simply put up, shut up and top up. So it's out with the tools and catch tray. We'll probably need some rags as well but if there's any justice in this world, or the workshop, they'll only get used to it...
Seals just fall due to old age from sitting in one position, petrol attack or environmental decay. Although any shaft that runs through a seal should impart very little pressure, the seal's lips can sometimes retain a memory. Very slight wear on both the shaft and its supporting bearing can be sufficient to just deform a portion of the oil retainer and thereby cause a oil leak.
No seal can accommodate a worn, bent or rusted shaft. Whether it's reciprocating or rotating, damaged steel always out trumps synthetic rubber. Excess heat, exposure to the inappropriate solvents(*) or UV sunlight can all damage seals. It's permissible to use a flexible gasketing agent on the edge of a seal if the case is damaged, worn or slightly out of round. However, there's a limit to what's viable and the choice of wonder-goo can have adverse implications for oil ways and/or subsequent rebuilds. Ideally all that needs to be applied when a seal is installed is a little oil or grease to aid fitment.
* Some Thai mechanics sometimes use petrol to clean the inside of an engine, with the arrival of ethanol fuel blends it's best to stop doing that... As most engine seals, even for the most modern motorcycles are not manufactured with the use of ethanol inhibitors...
