Unit13 Posted May 29, 2010 Share Posted May 29, 2010 Just a quick bit of information i have found on my 87 and 88 Z24 powered Pathfinders. I brought my 88 about 6 months ago with a bad cam chain that snapped on the way back home from picking it up (im a mechanic, i knew the risks). Anyway a rebuild was now in order and when i stripped the engine i found very badly scored cam and main bearings. On further investigation i found a shiny little ball in the black swamp of goo in the sump... the bypass valve ball. This helpful little friend resides in a special fitted tube pushed into the block directly underneath the oil filter. This ball and spring setup is a backup protection in case the engine is not serviced frequently and the oil filter becomes so clogged that it cant pass oil through. To prevent starving the engine of much needed oil, the preset spring and ball lift off their seat and allow UNFILTERED oil to pass through the engine. That's all well and fine, and hopefully the owner of the car would eventually get around to changing the filter therefore allowing the ball and spring to return to their seat and let the filter do its job. NOW after that little bit of info, the problem is, and has been confirmed by Nissan, these buggers have a habit of the ball breaking through the casing and falling through the drain hole in the filter housing and into the sump...as in my case. The reason being primarily having to continually snap on and off the seat with improper servicing...the main concern is that now with nothing to stop oil flowing through the bypass hole it does just that, rendering the oil filter useless... If you dont visually check that the ball is still in its housing and it has in fact popped out your in trouble. Its not easy to see at first, you have to have a proper look with a torch and maybe a mirror in the base of the housing plate where the filter screws on. If it has fallen out, you can use a small spigot puller or tiny slide hammer to pull the casing and spring out of the block and just tap a new one in (the ball in the sump wont hurt anything). I have had to replace both my pathfinders bypass valves for this reason. I checked around and i could only get them genuine Nissan. But the good news is they retail for the hefty sum of around $20 AUD...Cheaper then some oil filters. Let me know if after all that you still dont know what im talking about... Cheers Luke 1 Link to comment Share on other sites More sharing options...
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