What happens when a tank vent gets clogged on a W123.


For anyone that doesn't think the lift pump on a OM617 can practically suck a golf ball through a garden hose....here are two pictures of my fuel tank when the vent became fully blocked for some reason on a 3,200 mile round trip.

Two points of note.....the car never experienced a power loss, and it ran 80-90 mph during all of this. Right up until the fuel gauge suddenly stopped functioning with the only symptoms of a reduced fill-up volume. I drove the car another 4 hours after it crushed down this small, at this point it could only hold 6 gallons of fuel at most.


I guess these pictures are sized too big so you have to click the thumbnails for a better look.

Attached Thumbnails

   

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Did it make a noise at all?

Holy hell! I better fix my vent soon

No...no noise....nothing..... I was driving from Virginia to central North Dakota. Noticed through Minnesota the fill-ups were less than I expected....when I got to Fargo I should have had enough fuel to make it to my destination....and went from 1/2 tank to empty from the south side of town to the west side, pulled over expecting to see fuel pouring out and nothing....Had a fuel in the trunk and 4 gallons and it was to the top of the neck. So I got back on the highway and ran 80-90mph the next almost 300 miles. Got where I was going and it stalled, but restarted right up, but ran rough the last mile. Saw it crushed when I pulled the panel off...so I put 120 psi on a blow gun. wrapped a rag around it and jammed it into the fuel filler, popped the tank out......then hooked a hose up to the vent tube and after a moment heard something pop into the tank....then the vent was clear. Gauge still read empty....and expected something to read....emptied the remaining gallon of the one can, and emptied the second 5 gallon can, that brought the gauge up to 1/4. Next day took it to the station and put another 15 gallons into it.....so it was sucking air when it started running rough. It presented no symptoms on power, acceleration or smoothness until it was empty and sucking air as would be expected at THAT point. Only some suction at the cap.

No further events on the return trip....averaged 31 mpg based on the fuel receipts over 3,200 miles of the trip. And my Odometer and speedometer are almost spot on with the tires and gears I'm running.

And I hit the 200,000 mile point passing Cleveland, OH on the return trip.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

There is still a crease in drivers side of the tank but it popped back out to full capacity.

Didn't take a picture after I popped it back out.

It almost pulled the filler cap THROUGH the quarter panel at that point.

Not likely to happen on short trips....but I was running hard non-stop from fill up to fill up on the highway..no time for the vacuum to equalize from any imperfect seal. But I did stop for food and restroom breaks before hitting pumps for fuel....so it didn't seem as bad when I did pull the cap off than it would have immediately after getting off the highway.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Just as I suspected.... Minn. sucks.

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1985 300SD
1998 Jetta TDI
Previous: lots of diesel VW's, MB's, KW's, Pete, Freightliner


Walking isn't a lost art: one must, by some means, get to the garage.

That's frickin amazing ........

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Palangi

2004 C240 Wagon 203.261 Baby Benz
2008 ML320 CDI Highway Cruiser
2006 Toyota Prius, Saving the Planet @ 48 mpg
2000 F-150, Destroying the Planet @ 20 mpg



TRUMP .......... WHITEHOUSE
HILLARY .........JAILHOUSE
BERNIE .......... NUTHOUSE
0BAMA .......... OUTHOUSE

I decided to post those since there was a discussion recently about what a OM617 lift pump could and couldn't do....didn't remember which thread that was so made my own.

No hearsay here....happened to me in my own car recently...like a month ago.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Jesus. Thats impressive.

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

Any mechanically driven lift pump will collapse a tank if the vent is plugged. A Bosch VE pump with its internal lift pump (vane type) will also collapse a tank with a plugged vent. Ask me how I know.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Wow....talk about the unexpected.


Can I assume that my tank also has a vent that I should go take a look at just to be safe?

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1982 300GD Carmine Red (DB3535) Cabriolet Parting Out
1990 300SEL Smoke Silver (Parting out)
1991 350SDL Blackberry Metallic (481)

"The thing is Bob, its not that I'm lazy...its that I just don't care."

That is one tough lift pump you have !!! Sick ones would not pull the skin off custard.
I guess though that the low pressure was all the way around the fuel system so it was your IP high pressure elements doing the work.

I have seen fuel tanks expanded a little with air pressure to increase their capacity. You are lucky it didnt go bang !!
As a kid we once piped up 150 # to a 50 gal drum for fun. We ended up with 3 sheets of flat steel & a hole in the shed wall. Lucky we were not hurt. Our ears were ringing for a few days & our backsides were sore after dad found out what we had done !!!

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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

it's actually amazing how little vacuum it takes for the atmosphere to crush a steel can.
8 to 10 inches of vacuum should be enough to allow that flat long tank. I should put a gauge on one of mine, and measure how much vacuum it takes to collapse it.
heck, I ought to video the procedure...

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Please do!

... 3 sheets?
lid one, lid two, and the barrel itself?

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!