[Liam_Fox]

Hey all. New to the fourms however have been browsing since I got my car over a year ago. Searched around a while but hard to find a post with the exact noise. If I did miss one I am sorry.

I was attempring to fix my idle when I noticed this sound upon revving.

bad sound ka24e

bad sound pt2

Feel like its coming from topish of the engine? But sometimes it sounds like the trans area.

Car info:
Its a 1990 ka24e manual swapped by a previous owner.
Runs rich and the idle is a little all over, which is what I was working to fix when I noticed this. It runs and drives good, great even, other than it running rich.
Engine compression tested 150 across the board (lowest being 148 and highest 152).
Have done oil change spark plugs and wires a few months ago.

I have never noticed this, but I do not think it is a new sound, mostly becuase the exhaust used to be super super loud till last week and drowned it out. With the hood open this sound is very loud. Comes in at around 2kish and seems to go away over 3ish. If this engine is dying then I am not sure what I am going to do. Id appriciate any insight or info as to what this could be.

 

[collegekid]

So a true knock stays and does not disappear. Meaning your range of 2000-3000 rpm would not matter if it was a knock.


I'm sure there's countless videos on youtube on how to check if you have rod knock.

I recall a quick test to check for engine knock.
You have to have the engine off ( and cool).
Take out spark plugs.
Keep car in neutral.
Get a socket on the crank pulley and rotate it ( should be clockwise but I'd check that).
You want to check each cylinder. So you would start with cylinder 1.
You want to rotate the crank to see the piston come up, hit top dead center ( aka the top most point it will travel ) and watch it start to go back down.
Rotate it so that you see it go top dead center, and start to go down.
Take a long screwdriver or something that will fit in the hole and try to push down on the piston.
If you feel the piston move down quickly and almost make a clicking noise, then you have a rod knock.
You will feel some kind of play.
If you push down on the piston and it just feels solid, like nothing is loose, then it's not rod knock.
Check all 4 cylinders to be sure.

 

[Liam_Fox]

So a true knock stays and does not disappear. Meaning your range of 2000-3000 rpm would not matter if it was a knock.


I'm sure there's countless videos on youtube on how to check if you have rod knock.

I recall a quick test to check for engine knock.
You have to have the engine off ( and cool).
Take out spark plugs.
Keep car in neutral.
Get a socket on the crank pulley and rotate it ( should be clockwise but I'd check that).
You want to check each cylinder. So you would start with cylinder 1.
You want to rotate the crank to see the piston come up, hit top dead center ( aka the top most point it will travel ) and watch it start to go back down.
Rotate it so that you see it go top dead center, and start to go down.
Take a long screwdriver or something that will fit in the hole and try to push down on the piston.
If you feel the piston move down quickly and almost make a clicking noise, then you have a rod knock.
You will feel some kind of play.
If you push down on the piston and it just feels solid, like nothing is loose, then it's not rod knock.
Check all 4 cylinders to be sure.

Appriciate the advice. Probbaly gonna give it a shot. I do agree thought I dont think rod knock, wrote the op while still pretty upset lol. Some others have said maybe flywheel or starter related, I replace the starter (it was old and died) and that didnt change anything, at this point im guessing trans area or just a random bit that happens to be hitting something who knows.

 

[collegekid]

Appriciate the advice. Probbaly gonna give it a shot. I do agree thought I dont think rod knock, wrote the op while still pretty upset lol. Some others have said maybe flywheel or starter related, I replace the starter (it was old and died) and that didnt change anything, at this point im guessing trans area or just a random bit that happens to be hitting something who knows.

Yeah keep at it man.
My old ass truck has some weird pinging type noise that had me worried for a while but it wasn't knock.
I tested it with the method I told you and it checked out fine.
It's probably something on the exhaust rattling or it may even be the Airtag I put inside the dash that's just banging on something.

Point is, these aren't exactly new cars so you will develop some rattles here and there.
You DO want to make sure it's nothing engine related.
So keep at it and let us know what you find.

It would be good to get some gauges on it too ( oil pressure, oil temperature, and water temperature)
to make sure things are kosher.

If you have an old laptop lying around, you can also get a nissan consult cable and download ECUtalk if that program is still around. It will let you see all the sensors and what they are reading so you can accurately diagnose stuff without throwing parts at it.