Opinions on knock/loud tap? (video)

[TeeDiggs]

Dropped the 80 off to a body shop a few days ago to have some body holes welded up. When I picked it up today, a new engine knock/tapping is very present. I've occasionally had some minor tapping sound in the past year or two on very cold winter mornings until the engine warms up, but this is much more pronounced and does not go away.

• Does not go away on a warmed up engine, but does seem loudest on a cold engine.
• Power is normal, nothing feels different
• Knocking starts to get audible around 1k rpm, and volume/frequency does increase with engine rpm.
• I could hear it best when crawling underneath on US pass. side.
• Performed tune-up in July, new spark plugs, wires, dizzy cap, rotor.

Thoughts in meantime? I will try to poke around with my stethoscope on sunday. Not able to spend any time until then unfortunately.

 

[Kernal]

It would be interesting to see the results of a used engine oil analysis, have you considered sending a sample to Blackstone Labs?

 

[blkprj80]

I would suggest checking the belts, maybe one has chunked out.
If it's a rod knock, it will get worse and you'll know for sure. Hopefully not that though.

 

[Snoozecruiser97]

Mine recently developed what sounds like the same problem. Ive been researching and other than a rod knock ive read about a possible timing chain jump. Might need to get into the front engine gear setup to check it out.

 

[The Bumble]

Sorry to bring up a two year old thread, but I came across this one in my search for engine knock causes. My '97 has recently started making the same knocking noise as yours. Same description/symptoms, too. Someone (not me!) started it with the gas pedal to the floor and now there is a lovely knock. Did you ever figure out what was causing it? Timing chain issue, rod bearings, or something else? Thanks for any help!

 

[pknaud99]

sounds like valve train lack of engine oil try to use synthetic oil with additive it may help

 

[ajax1]

Could be piston slap

 

[BILT4ME]

Do a compression test on all cylinders

Pull a plug wire from each cylinder progressively to see if the noise stops when the spark plug stops firing on a given cylinder. If so, then you know WHICH cylinder.

If it stops on the above, then I would consider a wrist pin or piston slap, or a bad rod bearing.

Have you checked for exhaust leaks? They can sometimes give odd noises.

Also check your PS pump.

Use a mechanic's stethoscope to check various locations.

 

[The Bumble]

Thanks for the suggestions! I've never had to mess with engine internals, so this is a first for me. I'll give everything a good check and then try the spark plug wire trick. I'm hoping that it's something simple, but I know that it's probably not!! Thanks again.