So the last few days when I've gone out to start the car, and this doesn't happen every time... After I've glowed and right at the second the engine fires when I turn the key, I feel/hear this clunk that seems to come from under the car in the center, right under the dash. It's on my '85 300D. It starts and runs fine, and only does this maybe 2 times out of 10. Any thoughts?

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-RF
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1999 E320 Wagon - 170,000 miles

Check the air filter mounting bracket. I'm assuming its a federal 85 and not a CA 85?

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1982 240 D, 308,000 - 321,127 miles (sold)
1982 300 TD,166,500 - 226,000 miles
1998 E 320, 120,000 - 144,000 miles
2005 C 230 K, 26,000 - 77,000 miles (sold)

I'm not sure if you are referring to the air clearer mount (rubber piece, with screws on either side) but that did cause a lot of noise in my SD at idle. On inspection is was split in half, yikes!

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In the Garage:
'84 300SD, 85K "The Princess"
2011 BMW 328I XDrive, DD

Those are the mounts, which are attached to the bracket. All of which can cause similar noise at start up if broken.

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1982 240 D, 308,000 - 321,127 miles (sold)
1982 300 TD,166,500 - 226,000 miles
1998 E 320, 120,000 - 144,000 miles
2005 C 230 K, 26,000 - 77,000 miles (sold)

Well it has a brand new air cleaner bracket on it. Just installed 2 months ago. There is no noise at idle. It is only one clunk right as soon as the engine fires and then the idle is fine.

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-RF
______________________________________________
1999 E320 Wagon - 170,000 miles

How about transmission crossmember bolts/rubber bushings? Everything in place there?

Check the starter mount bolts

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Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

Did you check it? Did you install the $120 OEM or the $60 chinese bracket?

Mine lasted about 2 months as well ($60-chinese crap).

Could also be the air can itself hitting the valve cover at start up.

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1982 240 D, 308,000 - 321,127 miles (sold)
1982 300 TD,166,500 - 226,000 miles
1998 E 320, 120,000 - 144,000 miles
2005 C 230 K, 26,000 - 77,000 miles (sold)

engine shocks or shock mounts?

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car