V6 (1994-2004) Mustangs Technical discussions on the 3.8L and 3.9L V6 torque monsters

Knocking sound when warm AND in gear

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Old Oct 29, 2018 | 12:32 AM
  #1  
Bluebomber_v6's Avatar
Bluebomber_v6
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Joined: Oct 2018
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From: TX
Unhappy Knocking sound when warm AND in gear

Alright, this is my first post here so if I'm doing anything wrong, let me know.

2000 Mustang V6 with stock 4-speed automatic transmission.

The short version of the issue is that I'm hearing a metallic knocking sound coming from the front half of my car, there is no check engine light, and there are no error codes on the ecu.

It only happens when I have let the car warm up for 10-20 minutes, or I've driven a couple of miles, and it only happens when the car is in gear.
Once the car is at operating temps, I can rev the engine in neutral up to 2500k+ without any odd sounds (other than leaks from old gaskets I need to replace, we'll get to that soon though) but as soon as I put it in any of the drive gears the sound shows up and gets louder when revving.
I originally thought it was a spun bearing, or something in the valve train, but I inspected everything without finding the cause. The oil pressure stays the same and there is no noise when the engine is under load, so I am pretty confident that it isn't an engine issue. The idle speeds go down from 1000 rpms to about 500 when I drop it into gear.

I have already taken off the intake manifold, both valve covers, checked all 12 rocker arms visually, checked the plugs and wires. I have a few ideas, but I want some help before i start ripping more off of my car.

This car is my daily, so any and all suggestions for what to look for would be appreciated.
If you need any more info, please let me know and I'll get back to you asap.

Thanks, Josiah.
Old Oct 29, 2018 | 01:06 AM
  #2  
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Stepman
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Loose or cracked flexplate ? Or loose torque converter ?
Old Oct 29, 2018 | 01:11 AM
  #3  
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Bluebomber_v6
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Originally Posted by Stepman
Loose or cracked flexplate ? Or loose torque converter ?
Cracked or warped flexplate was one of my ideas, is there an easy way to check on it in my driveway? I've got jacks, stands, ramps, plenty of tools, and a day off tomorrow.
Old Oct 29, 2018 | 01:27 PM
  #4  
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Derf00
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From: AZ
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There is usually an inspection plate on transmissions to see the flexplate or clutch (on a manual). Not sure about your year.
Old Nov 1, 2018 | 02:52 AM
  #5  
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Bluebomber_v6
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From: TX
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Originally Posted by Derf00
There is usually an inspection plate on transmissions to see the flexplate or clutch (on a manual). Not sure about your year.
Sorry for the late reply, I'll try and get out there and see what I've got. It's been raining here and I'm working in my driveway so conditions aren't really optimal.
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