A friends 92 Maxima w/ VG engine has an intermittent upper end rap in colder weather. Sometimes it does it and sometimes it doesn't. He changes oil regularly w/ proper weight, uses quality filter w/ anti drainback, and overall it runs good. It started this about a year ago. I thought maybe oil passages are clogged causing poor circulation during start up, but he has run all kinds of products like Lucas, Marvel Mystery Oil, Rislone, etc so I don't think that's it. It has 140k on it and has been taken care of pretty well. Only other thing I can think is maybe the oil pump is the culprit. Problem is it can be 20 degrees out and sit all night and it won't do it. Then out of nowhere it does it. Real strange. Sounds like rocker arms tapping. Anyone have any ideas? I'm scratching my head??

 

Leaky lifters .................. if the motor stops with the leaky lifter under pressure from the open valve, then its going to leak oil that needs to first be replenished at startup before it will quiet down ............ its a sign of the times unfortunately. When the motor stops with the leaky lifter's cylinder at close to TDC then the lifter will not be under pressure because the valves are closed and the motor will start all nice and quiet.

Mine does the same - motor had nothing but the best care too, so live with it or haul out a huge chunk of cash

 

Well that kinda blows. He might as well just run it till it won't run no more. I think at that mileage if he wants to fix it going through the heads is just not worth it. A new motor would make more sense then dumping money into the top end. Because you know if the top ends nice and tight the bottom is going to go next.