Miata Turbo Forum - Boost cars, acquire cats. - Supercharger rattle/grinding

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- - Supercharger rattle/grinding (https://www.miataturbo.net/supercharger-discussion-38/supercharger-rattle-grinding-98913/)

Kiki	01-02-2019 02:46 AM

Supercharger rattle/grinding

hi everyone,

does anyone know what could be causing this rattle/grind sound from my Eaton m45 1.8 mk1? It only happens between 3500-3800rpm with performance not affected at all, thoughts were resignation from touching metal but any loose bits tied back and still happening. It's odd, I took it out the other day and with engine cold did a few pulls and no noise but once warm on comes the grinding again it's so perculiar.

It happens on accelerating and deceleration when going past 3500-3800rpm and at idle if revved to that rpm. If you hold it at that rpm noise stays the same and sounds like it's shredding it apart but been like this for a while now and still pulling the same.

Will check the cat in next couple of days to see if anything loose or rattling down there too.

andym

01-02-2019 09:48 AM

I am a bit confused. Did you remove the belt running to the supercharger and drive without the charger actually connected?

Kiki	01-02-2019 01:29 PM

Quote:

Originally Posted by andym (Post 1517148)

I am a bit confused. Did you remove the belt running to the supercharger and drive without the charger actually connected?

This is the car all together, been running like this for 2 months now, I've looked around and charger seems fine so must be a resonance of something at the rev range just don't know what, no power loss from charger and pulls well.

Balto

01-02-2019 02:12 PM

Pull the belt from the supercharger, it will still run without it (albeit not well). Just Rev it at idle to the appropriate RPM.

Vibration?

Yes = resonance, find rattling part.

No = problem with blower. Maybe out of balance or some bolts are too loose.

Kiki	01-02-2019 07:33 PM

Quote:

Originally Posted by Balto (Post 1517195)

its resonance 👍

hks_kansei

01-02-2019 07:45 PM

get a mate to rev it to where the noise happens.

Then just start poking shit, especially heat shields, with a broomstick until the noise stops.
Noise stops = part that's resonating.

If it's still got the stock exhaust heat shields there's a good chance one's snapped a mount bolt and now vibrates.

1RMDave

01-09-2019 08:27 AM

It could be a worn supercharger coupler (in the snout) I've had to do one on an m45, apparently it's a relatively common part to wear out. It can rattle or knock. But first and foremost make sure the noise is actually coming from the SC.

parrainx

01-12-2019 01:20 PM

Check the belt tensioner pulleys. My buddy had some rattles on his M45 and we thought it was the SC sent it to Magnuson for repairs and they said it was all good. Turned out ball bearings went out on the TRD pulley (same as timing belt idler).

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