After finishing my coolant flush and re-mounting the two belly pans I found to my shock a big bolt on the garage floor under the engine area. The hex bolt is about 1 1/2 inches with the head 1/2 inch in diameter and thread diameter is 1/4 inch as in the picture.

When I found it the car was still on jack stands and I was lying on my back under the car, so that no other action could introduce it from elsewhere.

I certainly did not touch such a bolt during my coolant R&R and I did not hear or see it fall down. My infinite worry is where it's come from. Such a big bolt when lost is no minor matter.
I'd appreciate if you can identify it. Thanks a lot!

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1996 E320 since 1/16/08, 171K miles as of Feb 2011

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1989 300CE - R.I.P. Dec 29 2007
Other MBs (sold): 1992 300E-24 - 1979 350SLC - 1984 230E - 1990 300CE

Maybe a distributor clamp screw?

Probably something dropped and lost years ago and replaced at the time.

Given this is a Mercedes, "distributor clamp screw" is a pretty funny guess.

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Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles

I hope it is like you said. It is almost like a surgeon finding some extra part after sewing up the patient

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1996 E320 since 1/16/08, 171K miles as of Feb 2011

---------------------------------------------------------
1989 300CE - R.I.P. Dec 29 2007
Other MBs (sold): 1992 300E-24 - 1979 350SLC - 1984 230E - 1990 300CE

MB parts are metric. Use the other side of your ruler

If the bolt diameter is 8mm and the hex size is 8 or 10mm, looks like a motor mount bolt to me. So, I rec you check them.

I took a look and found a lot of engine components which use similar hex bolt and the water pump is one of them. Others are intake manifold, the silver block under the water pump.

The problem is I see no hole, which misses a bolt, and no loose part when shaking. Of course without a lift to investigate from under it is difficult to see.

My indy replaced the water pump last year in August.

__________________
1996 E320 since 1/16/08, 171K miles as of Feb 2011

---------------------------------------------------------
1989 300CE - R.I.P. Dec 29 2007
Other MBs (sold): 1992 300E-24 - 1979 350SLC - 1984 230E - 1990 300CE

That's what my distributor hold down bolt looks like... Of course, I have a lot of allen heads on my engine where EPC shows hex heads.

Granted, if that's what it was, you'd know it pretty quick.

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A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.

That second hole you pictured is likely an unused mounting hole on your car....

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

texholdem. I am in Dallas. I own a 300E. contact me @ rickkhall@yahoo.com

first off, don't worry. If nothing's visibly loose, you're not going to loose anything any time soon.

You'd prefer not to be missing an accessory bolt, but it's not unheard of.

Just put it back and torque it down. Do be careful about where you put it, try and make sure it actuall is the right length for the hole you're screwing it into.

Over torquing a bolt or worse, bottoming out in a blind hole are not good things to do.

HTH -CTH

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- cth350@gmail.com
http://www.111lakeside.com/

Thanks, Is "allen bolt" the right name for it?

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1996 E320 since 1/16/08, 171K miles as of Feb 2011

---------------------------------------------------------
1989 300CE - R.I.P. Dec 29 2007
Other MBs (sold): 1992 300E-24 - 1979 350SLC - 1984 230E - 1990 300CE

not really. I think everyone would know what you're talking about, though! A hex bit is the tool used to loosen/tighten a socket head (allen??) fastener. A hex head bolt has an externally hexagonal head.

I guess it doesn't really MATTER what you call them, as long as we can all agree to call them the same thing. Shall we take a poll????

Cheers!

Jay.

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On the road, currently:
'83 300D (German spec.) 168k mi. - - Wolfgang (tucked snugly away for the winter!)
'87 300D 375k mi. - finally went over to "The Dark Side"
'87 300TD 225k mi.
Cannondale 66cm CAAD5 w/Campy/Jamis Aurora
Hujsak Custom Fixie/Landshark Track Shark Custom/Ahearne Custom 29'er

I believe the proper terminology is 'socket head cap screw'.

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Fred Hoelzle

First, I'm inclined to go along with the suggestion that it was on the ground when you started. From the look of it, it hasn't been in a hole for a while. If it was, the portion of the threads that were in use would be much cleaner.

Having said that, it appears that it would take about a 4 or 5mm hex bit, either of which are used on the throttle linkage brackets, the throttle body and various brackets securing components to the manifold and head such as the EGR tube, etc. Maybe also look at your cruise control unit where it bolts to the block.

It was certainy not on the garage ground when I started, maybe it was loose and fell into the belly pan then landed on the floor when I removed the pan without my knowing.
So it is not advisable to put the bolt to the first hole I saw, I gonna look again. I appreciate your inputs.

__________________
1996 E320 since 1/16/08, 171K miles as of Feb 2011

---------------------------------------------------------
1989 300CE - R.I.P. Dec 29 2007
Other MBs (sold): 1992 300E-24 - 1979 350SLC - 1984 230E - 1990 300CE