What is this sound? 1991 Nissan D21 Pickup

[chaddeihl]

I have a 1991 Nissan D21 Pickup - 4cyl - 4x4 pickup. I have a knocking noise in the engine that comes and goes. Sometimes its not very noisy, other times it is somewhat loud. The noise increases as I hit the accelerator. The AC is not related. I have uploaded the sound from my cell phone to my domain - please listen and someone let me know what the sound is. I am wondering if maybe its a manifold issue. Any information you can provide will be great. Thanks.

http://www.justinloveday.com/knocking.m4a

[Rev_D21]

Sounds like a rocker to me. I'd use a stethoscope to pin point whether it's coming from the head or the block.

[longtooth]

Sounds like a rocker to me. I'd use a stethoscope to pin point whether it's coming from the head or the block.

2nd on the noise.

[chaddeihl]

Sounds like a rocker to me. I'd use a stethoscope to pin point whether it's coming from the head or the block.

Is there a difference between a rocker and rocker arm or is it the same thing? I am not a mechanic. I am just trying to figure out if this will cost me a bunch to replace or not. How long can you run your engine before this is a MUST fix?

thanks

[longtooth]

Cant really give a time line on that. Best bet would be to remove the vlave cover and check you valve lash.

[1991Hardbody]

While you have the valve cover off, check timing chain slop and make sure guides are ok too!

[seang]

Here is the Nico tech article on cleaning KA24E hydraulic lifters, which are located in the tips of the rocker arms: http://www.nicoclub.com/articles.php?id=215864

I never ended up doing this to mine even though they did get a little noisy sometimes, just not scary loud.

[RT22]

Dumb quick question If i pop the cover and remove and clean and put them back any adjustments needed? I used to adjust my motor cycles that had screw tappet, but on these if you just remove clean and replace how to be sure they are back in original spot?