Mystery Tap/knock. Video, can you identify?

[IwantMKIII]

This problem has been a long time running. The past few months I haven't noticed it at all. GaboonViper85 (tyler) knew it was a concern of mine when tranferring the engine to a new body but saw no metal shavings linking to any type of early rod knock.

My head was rebuild with the engine about 15K miles ago. The noise is focused towards the front of the engine (near all the pulleys and rotating parts). I've had a similar noise before and it was bad OBX cam gears. Im using stock now. The sound goes in and out decibel level wise as you may notice in the video. Sorry for the windage noise. Focus and youll hear metal on metal tapping, especially as i pull it away from the engine towards the end. Also, this only tends to happen (at least i noticeably hear it even with the hood closed when the engine is hot).

[youtube]sBqq6Z2dqmg[/youtube]

 

[lowtaco]

Could be valvetrain noise, maybe one wasnt shimmed correctly?

 

[teebone]

Can you put a stethoscope on the fuel rail and rule out noisey injectors?

 

[jdub]

Have you removed the accessory drive belts and run it?

 

[IwantMKIII]

Have you removed the accessory drive belts and run it?

No i did not, but thats a good idea.

jdub, is there a possibility this could be linked to the oil pump?

It COULD be my oil pressure gauge (it is aftermarket cobalt series autometer) but even after i shimmed the oil pump i saw no real noticeable pressure raise and still maintain 0PSI with hot oil at idle. I also maintain only about 30Psi at 3k rpm hot which is only about 2Psi over when it wasn't shimmed.

 

[IwantMKIII]

Can you put a stethoscope on the fuel rail and rule out noisey injectors?

I have used one before earlier in the summer. I could hear it all the way through the transmission case. Its loudest point i could get to was from the oil pan near cylinder 1/2 or same area on the top near the valve covers.

 

[radiod]

Try running it without accessory belts like jdub has mentioned. Check and make sure your cam gear bolts are torqued properly. See if you can borrow (or go buy) a mechanic's stethescope and check to see if it's coming from the valvetrain or the injectors. If it's the valvetrain, I would put my money on a valve/shim being out of adjustment.

Can you get a sound clip blipping the throttle or varrying the rpm?

 

[IwantMKIII]

Can you get a sound clip blipping the throttle or varrying the rpm?

yeah, next time i take the car out to heat it up enough ill make one

 

[jdub]

No i did not, but thats a good idea.

jdub, is there a possibility this could be linked to the oil pump?

It COULD be my oil pressure gauge (it is aftermarket cobalt series autometer) but even after i shimmed the oil pump i saw no real noticeable pressure raise and still maintain 0PSI with hot oil at idle. I also maintain only about 30Psi at 3k rpm hot which is only about 2Psi over when it wasn't shimmed.

Not likely it's the pump, but it could be the drive gear/shaft.
Check your oil pressure with an external mechanical gauge at the sender location.

If the noise is still there after running with no accessories, you know it's in the engine. If it disappears, add the belts on one at a time till you hear it again.

 

[IwantMKIII]

^got it. Ill try taking off the belts saturday and see what happens.

 

[grimreaper]

id be interested in more oil psi readings if you get them.

 

[IwantMKIII]

I have no mechanical gauge here at school^ so id have to buy one.

 

[dumbo]

I'm a believer in oil samples now

I doubt it's your injectors, you can hear them pretty well at one point there. Other than that it's pretty hard to tell in that video.

Does your stock and autometer both read 0psi@idle!?!?! And the fact that shimming your pump didn't raise the pressure is bad. Prolly means your pump is flowing all it can...or your gauge is whooped. Do you have oil pressure at cold idle?

I would do an oil sample ASAP, and when your waiting for the resuts, do what jdub said and eliminate the belts.