Got my 300d back from the shop after some new oil cooler lines were installed. Happy day. I always enjoy visiting with my friend Mo who runs the shop.

I had to wait a bit while he was dropping in the last cylinder on a 911 turbo engine rebuild, kind of fun to watch. While he was doing this, he told me a story about a customer of his who destroyed the motor of his 300sd in a very stupid way.

Help me confirm if this story could possibly be true.

After filling his car with gas while on a roadtrip, he merged on the highway to see diesel fuel spilling out the back. He immediately pulled over and noticed he forgot to insert his gascap. Being a genius, he knew that his oil filler cap could work for his fuel cap, and a rag could jammed in the the gaping hole could adequately function as the oil cap. Mo claims he made it less than a mile before the rag was sucked inside the valve cover and jammed open some valves which had a violent collsion with the piston at 3,000+ RPMs. This resulted in Mo doing a full rebuild.

Could this be possible? I didn't know one cap could fit over the other. I can't remember the year, but I think it was a W116. Wouldn't a rag substituting as a fuel cap, rather than an oil cap, be smarter?

I know diesel prices are high, but jeeze. Could anyone be that stupid?

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!

I know the fuel cap on the my 83 wagon is the same as the oil filler hole. I would think a w116 could be the same. Why didn't he put the rag in the fuel neck? Would seem better.......

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-Randy Wakefield

1969 220D 4 speed (parts car)
1976 280C
1976 280S
1981 240D 4 speed (parts car)
1982 300D
1983 300TD (Ivory)
1983 300TD (gold)
1985 300TD (gray)
1987 190D 2.5
1970 280SEL (sold)
1977 240D 4 speed (sold)
1974 280 (rusted to death)
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1927 Chevy 4 door sedan
1938 Chevy 2 door sedan
1950 Willys Jeepster
1955 Studebaker President 4 door
1977 Ford F250
1979 Glastron 17'
1948 John Deere A
1960 John Deere 2010
1979 Satoh S650G
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2000 Bichon (Doby)

On the later W126's it doesn't work, but on the eary ones it might if you have the original metal cap. If I remember correctly I tried it on my 82 SD and it didn't fit, but I could be mistaken. I know for a fact that the new plastic oil cap that MB sells won't work.

However a rag in the valve train at 3k+ would probably destroy the engine.

Edit: just saw it was a W116, they might swap.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

The oil and fuel cap are the same. I lost my oil cap once and used the fuel cap to get home, but I ended up with diesel all over the side of my car AND oil all over my engine.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

That sounds possible, but dumb. The rag could easily get twisted around the camshaft and jamb up the valves. Obviously, I would have stuffed a rag in the fuel filler.

I am kinda leery about this one. Diesels do not suck, they blow. If they created suction, there would be no need for a vacuum pump.

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Dave
1983 300D Daily Driver

yeah definitly put his rag in the wrong hole. I've done the fuel cap for oil cap thing before too.

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

Perhaps sucked was a bad choice of words. Mo mentioned he jammed the rag deep enough in the hole so it would stay there...

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!

Filling his car with "gas" and "oil filler hole"- that made me laugh. Yes if you stick a rag inside the valve cover something drastic could happen.

Noticed I used both gas, gascap and diesel fuel. Gas is more of a slang term for fuel than anything else. As for oil filler hole, yes, I admit, my car vocab is developing. Finding humor with that is a bit condescending if you ask me. Please bear with me while I learn the lingo. I'm not a master mechanic, as you can tell.

I think stating gas as diesel breaks one of the 10 mb shop diesel forum commandments, whoops.

Anywho...

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!

Ive done it, oil caps from pre 81 diesels work on gas caps as well. very interesting lol. A rag? Thats ugly, Theres a way to get some monster lift on your cam

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Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac?

As long as they would add one additional commandment for you to keep thy religion to thyself.
George Carlin (Wonder where he is now..)

1981 240d (engine donor 1983 240d) recently rebuilt engine hurray! - No more.. fought a tree and the tree won.

pearl black 1983 240d 4speed (Converted!@$$%) atleast the tranny was rebuilt.

The story is believable to me.

I once left a rag in the engine compartment of my 59 vw beetle air cooled. The rag happened to be long and narrow.

So one day I was whipping along the road at about 60 or so and the little bug started slowing down....at first I thought maybe it was running low on fuel, then it started to bind up, so I pushed in the clutch and coasted to a stop on the shoulder.

I decided it must have gotten hot and so when it cooled down I drove it someplace where I could work on it and started trying to take off the shrouding that encloses and directs air flow from the fan to the places it is needed. Before I had gotten very far I discovered my oil checking rag in the cooling fan all wrapped around inside it so that it blocked most of the air flow.

Dooohhhh! I had thought that the air intake for cooling was ducted from the grill under that back window to the cooling fan.....its not.

So, yeah, the rag could have gotten wrapped around the cam and held the valves open and it would probably happen so fast that before anything was noticed....OUCH!

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

condoms are soo useful in more ways than one


I lost my fuel cap at a gas station once. I had no idea how I could have(didnt know about the spring that doubles as a cap holder)... so.. I was like.. hmmmmmm and rummaged through my glove box and found on... took it out and put it over the fuel filler hole and tied it off tight so no diesel would pool in the resevoir cap


I remember some tool did the same( with a rag) on one of the mitsubish forums I used to frequent

And you say you've never been to the drive-in, yet you keep condoms in your car?

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!

actually.. it was one I tossed in there incase I needed to make some form of gasket or seal... Keeping condoms in the car is a bad idea since it breaks down the latex or w/e stuff they are made from.

I was a boy scout so.. I'm Always Prepared