Please, help identify knock.

[Mishka]

Hello, everybody!

First things first it's a '95 240SX KA24DE.

Just a few days ago I noticed this knock from under valve cover at right above 2500 rpm. The sound seems to go away when I rev past 3500 rpm. The sound itself is like muffled knock. I hooked up an oil pressure gauge I had laying around and it showed good oil pressure, 45-50 psi at idle when cold, around 20 psi when hot. (I know it may sound a little high, but before that I replaced some of the oil with Lucas) With this oil pressure I guess I can assume that it can't be main or rod bearings. When I took valve cover off I found plenty of oil everywhere, everything is clean, no signs of damage of any kind.

The only thing I found that I didn't like is that the upper chain tensioner was sort of loose, I mean I can move it from side to side. Is it normal?

Another question is: How to check hydraulic lifters?

What you guys think?

[ILikeMy240sx]

Where is the noise exactly coming from? Front of the valve cover or on top of the valve cover?

[Mishka]

Seems to come from the front.

[Simbolgades]

Does it sound kinda like a big coffee grinder? If so, it could be the timing chain guide at the top of the cylinder head. On both my car and my girlfriend's old car ('91 FB, RIP), these broke off. The service department of my local Nissan dealer told me the factory instructed them to remove this piece from any KA that came in, apparently because it's only real function is to break off and cause alarmingly loud noises.

Chris'92 coupe