Clapping from either the back I of the throttle body or coil pack

[Don Smith]

Brand new to GN's and turbos in general. So I'm trying to learn from reading every post I can find on strange engine sounds. My history is I just picked up a 87 with 60k miles from the original owner. Did all the things suggested on this board, new fuel pump, hotwire, change all fluids, plugs, vacuum lines etc. after the cars warms up I hear a clapping sound from either behind the throttle body or the coil pack. Has no correspondence with the engine rpms. Just clap, clap, 10-15 secs, clap, clap, 5 secs clap. The engine runs a little rough. It's not on the road yet so I am doing all my testing in my garage. Can a faulty coil pack clap/clank? Any other suggests to what this could be would be appreciated, thanks,
Don

 

[GerrywithaG]

arcing? make sure wires are secure.

EDIT: just read the 'no correspondence with RPM'.

 

[earlbrown]

There's a bolt behind the coil pack that bolts it down the the black bracket. Is that bolt loose or missing?

 

[87-WE2]

Try posting a video of it??

 

[Don Smith]

I will check for that bolt tomorrow and try to take a video of the sound. It sounds muffled so I don't think it's the bolt but I will certainly check that. Thank you for these suggestions.

 

[pacecarta]

o

 

[Heisenberg]

By definition - it must be RPM related - since I'm assuming it only happens with the engine running - not KOEO
Once the engine starts - if it's actual engine noise - it must be RPM related.
It probably just isn't as obvious related to RPM.
Crossover pipe leaking?
The only other few things not connected or keyed to rotating assembly are inlet related - but kind of obvious and not on the back side
I'll be curious to see what this turn out to be.
Clapping - from a coil pack...not feeling that.

 

[Heisenberg]

A clapping noise from "either behind the throttle body or the coil pack" is in the general area of valvetrain.
However, the motors are notoriously difficult to pinpoint noises from.
I also wonder about belt tensioner - although they tend to respond to RPM

 

[salvageV6]

Could be up front too, check the belt tensioner assy or any accessory bracketry.

 

[pacecarta]

b

 

[TRICKSIXPA]

Hey Don wasn't the sound more of a clicking sound. Def something going on from what I heard on the phone but it was like he said random not in line with the rotation.

 

[Don Smith]

It's coming from the back end of the motor for sure. A little more history. I first started the car and the oil light came on. Ran for 20 secs. Replaced the oil sending unit and another restart, no change oil light on, another 20 sec run. Hooked up a oil pressure tester, no pressure, so 3 dry runs each about 20 seconds. Primed the oil pump by pouring oil down the oil line to the radiator. Test gauge shows good pressure. So 3 dry starts each 20 secs or less. Did I wipe the cam/lifters? I'm a SBC guy and the clap/clicking noise doesn't seem consistent with what I would expect. The sound only starts after the engine runs a min or so when it starts to warm up. Thanks for all the help Stefan!
I,ll try the above responses later today. Thanks for all the help!

 

[Don Smith]

I'll get a video post today as we'll,

 

[Chuck Leeper]

The noise could be a flat cam, [exh lobe] causing a thumping noise in the intake???
Pull the valve covers and see what the rocker action looks like.

 

[Pronto]

Did the noise happen when you first got the car or after you did all the work?

 

[Heisenberg]

It's coming from the back end of the motor for sure. A little more history. I first started the car and the oil light came on. Ran for 20 secs. Replaced the oil sending unit and another restart, no change oil light on, another 20 sec run. Hooked up a oil pressure tester, no pressure, so 3 dry runs each about 20 seconds. Primed the oil pump by pouring oil down the oil line to the radiator. Test gauge shows good pressure. So 3 dry starts each 20 secs or less. Did I wipe the cam/lifters? I'm a SBC guy and the clap/clicking noise doesn't seem consistent with what I would expect. The sound only starts after the engine runs a min or so when it starts to warm up. Thanks for all the help Stefan!
I,ll try the above responses later today. Thanks for all the help!

Ut oh....

 

[earlbrown]

^What he said.


Drain the oil and cut open the filter if you'd like to see what happens when an engine's ran dry. Might be a good idea to go ahead and drop the pan to get most of the debris out. (for some reason GM left a 1/2" boss on the inside that keeps you from getting a full drain)

Or just pull it after you get the engine out.

 

[Don Smith]

I drained the oil into a paint strainer as well as the oil filter and everything was clean but I do fear I wiped the lifters and cam. Going through the suggestions above and will pull the v cover and see how the rockers look. So much for the original owner stating he started the car regularly even though it hasnt been on the road since 93.

 

[Pronto]

So this was the first time you actually heard it run?

 

[Don Smith]

Yes, first time I ever started it. IT was in a guys drive way next to the property I hunt. Got to know him pretty we'll. he said the car was his baby. Drove it until 93 , last nj inspection sticker, and parked it. Said he started it for the next 8 years until the battery died. Started it a year ago then it sat until I towed it home. Been out in the garage for the last 3 hours pretty much laying on the engine trying to pin point that noise. It does move from side to side so I am assume the lifters- cam is wiped from me not priming the oil pump. I am going to get a second opinion from a guy Stefan (trixsixpa) referred me to, Paulie. He only lives one town over and he suppose to know gn's we'll. Not the end of the worldl if I have to do a full motor rebuild. At that point I might as well do a complete restore. The car doesn't have a speck of rust on it but the engine compartment does look like a 25 year old car. Plus I am see oil dripping down the turbo where it bolts together so here comes another full restore I guess. I have done 3 69 z28's in the last ten years so what the heck.