Buzzing Noise/Groan from Intake/Valve Cover

[tylerrose]

Hi all,

I have a strange sound coming from my intake runner/valve area (assuming valve train related.)

The timing is obscure - It only happens when the car is slightly warm and lasts for approx 2 mins of idling/driving. Ie. after cold starting the car, it makes the noise when the car has ran for 1-2 minutes. It happens additionally when starting the car slightly warm after sitting for 1+ hours. The sound is a 'groan' or buzz and follows RPMs. It sounded like a failing accessory, belt or pulley to me, but it is coming from a different part of the engine. A video can be seen here: https://www.dropbox.com/s/fplop3nr1qq9m ... M.mov?dl=0

Any insight is much appreciated.

Tyler

[tylerrose]

Bump... no insight?

[plip1953]

Sounds always seem to exaggerated on videos!

What kind of mileage has the engine done? And have the valve clearances been checked/adjusted in recent times?

[86_6series]

Sorry I can't hear from the video.
I would use a stethoscope at first start and see if you could
locate the area more accurately. Noise has a funny way of
traveling. So I'm assuming it was an auto and you did a 5 speed swap,
because Euros used a 265 I think.

Also, use the stethoscope on the alternator, water pump and
a/c compressor clutch to eliminate any bearing noises,
may even be the fan clutch rattle.

Could it be the throw-out bearing rattling until it warms up?
But you would hear a different groan when you would step on the clutch,
so that can ruled out quickly.

[tylerrose]

Sounds always seem to exaggerated on videos!

What kind of mileage has the engine done? And have the valve clearances been checked/adjusted in recent times?

Car has seen 106k miles. Last valve adjustment was summer 2018 and about 3-4k miles ago.

[tylerrose]

Sorry I can't hear from the video.
I would use a stethoscope at first start and see if you could
locate the area more accurately. Noise has a funny way of
traveling. So I'm assuming it was an auto and you did a 5 speed swap,
because Euros used a 265 I think.

Also, use the stethoscope on the alternator, water pump and
a/c compressor clutch to eliminate any bearing noises,
may even be the fan clutch rattle.

Could it be the throw-out bearing rattling until it warms up?
But you would hear a different groan when you would step on the clutch,
so that can ruled out quickly.

The car came out of the factory as a five speed.

My first thought was an accessory/fan clutch, but with the stethoscope, I traced it further back on the engine.

I didn’t notice any consistency with the clutch but will check it out. I’m seeing now that the sound isn’t very noticeable in my video. Let me try and take another one. It’s not one of those subtle noises that only a trained ear can hear.

[Lbs6]

One thought, if you haven't checked the torque on the banjo bolts maybe one has migrated itself against the cam or rocker. Remove the cover and check it out, pretty simple job. Short length of hose works well for a listening device before removal of the cover.

Good luck
Leonard

[86_6series]

I must have read another post where they mentioned a 260 and thought it was you.
I stand corrected.

Traced noise to back of engine, maybe a scored cam tower?
Good suggestion to check the banjo bolt.