[John from Madison CT]

I'm long overdue on much maintenance for my '98 Yamaha EFI 250hp OB. One thing I've forgotten for a few years is the Oil Reservoir (3gal tank) filter/strainer. From a blown up diagram over at www.boats.net it appears that the filter is very small part, very close to the pump itself. Since the pump is hidden behind the tank, the tank probably needs to be moved off it's mount and access is needed to the rear. Has anyone ever done this filter replacement themselves and am I missing something obvious? Thanks, John

[Osprey]

John,You are correct. The filter is a small inline unit, black, that looks almost like a hose coupling. The pump, hoses and filter are recessed into the outside of the tank. You will need a couple small wire-ties as well.Since it will need to be removed anyway, take the opportunity to drain all oil and wash out the reservoir. You will be surprised how much sludge is likely in the bottom of the tank. Dish soap and hot water works fine. Then let dry before reassembly.

[rodbolt]

hello while we are dealing with neglected maint. when was the last engine oil tank water trap service? when was the last VST filter service? when was the last O2 sensor service? and when was the last low pressure fuel pump rebuild/replacement? all of the above can cause catastrophic piston failures. good luck and keep posting

[John from Madison CT]

Rodbolt: I've heeded your warnings and have begun the process of maintenance on my Ox66. I cleaned the O2 sensor a week ago. This was done after probably 600 hours of engine use. Remarkably, it was very clean. No obvious signs of carbon build up on the sensor, it's housing or the transfer tube. Next is the VST filter replacement. I need a warmer day to do that, but I now know how to do it. Over the winter, the low pressure pumps are being replaced too, just for normal preventative maintenance.

[rodbolt]

good deal. stay on top of the maint and most of those motors live a long and happy life