Clonk after engine shutdown

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Roger T
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Post by Roger T »

Is the clonk as the engine is running down to a stop. If it is, the supercharger may be the source of the noise as the rotors bang together as they are stopping. I got my supercharger drive compensator changed under warranty. If the engine has definitely stopped and then clonk then it will not be the supercharger.

SESH
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Post by SESH »

Engine has stopped completely, then after 3-4 seconds there is a clonk!
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simpleR
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Post by simpleR »

So it must be an accessory that continues to move/spin after engine stops.

Fans? They are at the front, spin and might continue to spin for a few seconds after engine stops until they slow to a stop? Maybe.
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Tel
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Post by Tel »

My gut feeling is fuel shutoff solonoid.

Mine does the same.
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SESH
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Post by SESH »

Car was booked in for service on 20 April at main dealer, now deferred until 21 May due to lack of staff.
I told them about the clonk and they said they would investigate at service.
Definitely something closing off (relay or pump) after engine shutdown.
SimpleR, the car makes the same noise whether hot or cold, so doubt the fans would be running when cold.
Tel, you could be right about fuel shutoff solenoid. We will see.
Mike
2020 Mustang Bullitt
Highland Green
1966 Corvette Stingray Big Block
1973 E Type Convertible
1963 Triumph TR4
Ex F Type V6S MY2016
SESH
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Post by SESH »

Update.
Car was booked in for a service and noise was tracked down by dealer as a problem with play in the supercharger pulley. Car has only done 20,000 miles.
Car was booked in for repair early this week on Tuesday.
Got the car back Friday with a new pulley mod. Supercharger had to come out.
Mike
2020 Mustang Bullitt
Highland Green
1966 Corvette Stingray Big Block
1973 E Type Convertible
1963 Triumph TR4
Ex F Type V6S MY2016
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Tel
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Post by Tel »

SESH wrote: Sat Jul 11, 2020 5:36 pm Update.
Car was booked in for a service and noise was tracked down by dealer as a problem with play in the supercharger pulley. Car has only done 20,000 miles.
Car was booked in for repair early this week on Tuesday.
Got the car back Friday with a new pulley mod. Supercharger had to come out.
Mike
Thanks for letting us know Mike - A number of forum members don't bother which is annoying!!
2016MY V8R IRR
ITG Maxogen Cold air intake kit
Billet OBD lock
Forged lightweight Blades
Full custom Xpel Ultimate PPF wrap
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SESH
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Post by SESH »

A pleasure Tel.
It's always good for future reference in case others have similar symptoms.
Mike
2020 Mustang Bullitt
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1966 Corvette Stingray Big Block
1973 E Type Convertible
1963 Triumph TR4
Ex F Type V6S MY2016
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Tel
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Post by Tel »

SESH wrote: Sat Jul 11, 2020 11:56 pm A pleasure Tel.
It's always good for future reference in case others have similar symptoms.
Mike
Most true.

I did whip the belt off and felt my backlash after just 15k miles - There is about 5mm +- before the coupler engages with the driveshaft.
I'm happy with this at the mo, but I think that it's another item that will need to be addressed as the miles go on.

No wonder the likes of SNG Barrett do so well!
2016MY V8R IRR
ITG Maxogen Cold air intake kit
Billet OBD lock
Forged lightweight Blades
Full custom Xpel Ultimate PPF wrap
Piano Black badges
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Black exhaust tips
Porterfield RS-4 Carbon Kevlar pads
Mich PS4S's
+ more 💩
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captainham
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Post by captainham »

Mine is currently in for a similar issue, the rattle at idle was barely noticeable but the clonk during engine shutdown was obvious. JTB00356 and SSM74810 were cited. They've now replaced parts within the SC but I don't get the car back until next week so not sure exactly what they've listed on the invoice, I'll let you know.

I'll enquire as to rough cost as this is done under extended warranty, but I think it's around £1500 (mostly labour to remove and replace SC snout). I also believe the parts are upgraded and rated to last 100k miles as the torsion couplers (think that's what they're called...or isolators...or something!) have become a bit of a known weak spot.
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