Knocking motor

[1999eclipsegpm]

Alright so about a week ago my car started knocking and its been down since, ive pretty much done every test i can and have concluded i am going to pull the motor. Does anyone recognize this sound and what the problem was so i can start there on the rebuild. It still runs, does not over-heat, does not knock on idle or light rev. The top of the head is fine, all valve springs rockers and cams appear fine. Compression test was 125-135 on cylinders 1,2,and 3, and cylinder 4 was 90. Any ideas??

Here is the video:
IMG_1582_zps268753a8.mp4 Video by Gregspuck | Photobucket

 

[ICM_MikeLago]

Is the idle rough? I just had the same issue. I dropped the oil pan and seen metal shavings. Then I examined the rod bearings and found that was the issue.

 

[1999eclipsegpm]

It idles fairly smooth

 

[DSM1G90]

Got a rod bearing getting ready to go, if it idles fine since there is no work on the connecting rod.

It's when you add sudden pressure in the compression chamber from the ignition of fuel that adds work to the rod bearing.

Time for a bottom overhaul.

 

[wparks]

I can't tell much from the sound on the clip other than it comes and goes oddly.

Usually a rod knock will be heard when you accelerate, at 1/4 the frequency of the firing pattern, and the load is greatest- and also importantly, it will knock again as well when you let off the gas and the vacuum in the cylinder loads the rod in the opposite direction. This is different than a top end issue, which may only show at idle, or one rpm, or on acceleration but not on deceleration. I'd pull the valve cover and look for damage, pull the pan and look for damage, shavings, etc. Good luck!