The O-ring around the manual tensioner bolt on Honda CX500s and GL500s can leak a surprising amount of oil once it stops working properly; here’s how to change it. Please note that due to the design of the bolt you cannot remove it far enough to access the O-ring while the rear engine cover is still on the block, meaning that you need to remove the motor to get access to that little O-ring. Because of this – and the fact that it should cost under a dollar for an O-ring of that size from a bearing shop – it’s often recommended that you change it as a matter of course when you have the engine out to do other work if it hasn’t been changed as far as you know. You can remove the old O-ring easily with a pick or similar tool:
The O-ring – 6.5mm x 3.1mm – is part number 91312-415-000 (eBay US
Clean up the bolt and the recess that the O-ring sits in then slide it over the end of the bolt:
All done. If you are doing this as part of a triple or quadruple bypass click here to go back to the main page.