High pitched whine under light load - Coyote/TKX/Moser 8.8

[JeffP]

Hi,

I've been running around in gel coat and shaking out all the little gremlins - fortunately there have been very few. One thing I've noticed is a very high pitched whine/squeal that occurs under a light load - ie accelerating from around 1800-2500 rpm. Happens in any gear as long as its a light load.. if I let off the gas it goes away, if I accelerate harder it goes away. Its not a belt squeal - much higher pitch. I'm not sure I can capture it against the sound of the engine itself but I may try unless someone has any ideas.

Thanks!
Jeff

[michael everson]

where did you route the breathers on the valve covers? On My first coyote build, I tied them together and sent them to the intake tube. It caused a crazy whistle. Only one can go to the intake tube.
Mike

[JeffP]

I assume you mean these two? I attached them per the coyote guide. passenger side goes up under the cover

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following these pictures:
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[golfobsessed71@gmail.com]

Not sure it's the same but I had that exact thing going on with my 33 hotrod, high pitch whistle in the 1800-2000 rpm range, could pedal in and out of it... turned out to be my fuel pressure regulator

[Rdone585]

Have you eliminated the idler pulley. If you are able to replicate it with the car not moving, use a stethoscope to diagnose. If you don't have one any long stick or metal rod will do. Just be really careful not to get it caught in any of the pulleys or rotating pieces.

[JeffP]

Have you eliminated the idler pulley. If you are able to replicate it with the car not moving, use a stethoscope to diagnose. If you don't have one any long stick or metal rod will do. Just be really careful not to get it caught in any of the pulleys or rotating pieces.

Thats a good call, I haven't tried reving it in neutral to see if its there. I feel like its more drive train vs engine related but that test will certainly help isolate it. I'll try that and report back.

[JeffP]

Doesn't make the sound when in nuetral or not moving. Only makes it in gear, almost sounds like the clutch - kinda has that high pitch metal and metal sound. I would think if the clutch were slipping though it would be prominent throughout the power band and not just around 2k.

[BaBaBooey]

Rear gears can have whine like that sometimes if set up improperly or worn or loose. They can be more noticeable under acceleration, then goes away or quiets if you let out of the gas.
Its a whine noise. Some people would describe it as high pitched I think.

[michael everson]

Some of the cast aluminum bell housings needed to be relieved inside because they touched the teeth on the flywheel. Maybe that’s the noise your hearing. If so it will go away eventually.
Mike.

[tonywy]

As described it sounds like the rear gear assembly. Typically if the preload on the pinion bearings is set up to tight or loose you will get noise. Also it could be the gear set, different manufactures are more noisey than others. Ford Motorsports are usually quite. Get a suction gun and pull some oil out of it and see if it's filled with metal filings. Some is normal especially on a new set up.