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  #1  
Old 01-24-2018, 08:12 AM
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A pair of leaky '72s

First off, I need to say, both these vehicles belong to friends of mine, and they're leaking gas. Neither car is driven regularly. Unfortunately, car #2 is in a garage and won't start, and I'm currently 200 miles away and have no way to look at either right now, or send pictures. But here goes.

First is a 1972 W115 220.
The side-draft Stromberg carb has a small vacuum hose going from under the carb to the intake manifold that's leaking gas.
I did look at this awhile ago, and it's definitely a vacuum line - not one of the fuel lines. And of course, it's dripping right in the area of the hot exhaust system!
Should there even be raw gas in this line, or could this indicate some sort of carb malfunction?

Second is a 1972 W108 280SE 2.8 sedan.
One or more of the rubber fuel lines to the electric pump are leaking. My friend says it's not the supply line from the tank, but one or more of the other lines at the pump.
IIRC, the discharge line has a threaded fitting.
But my friend says the lines that are leaking have clamps, including a "three-way" line or connection (he mentioned something about a "regulator") and he wants to replace the lines himself. It's a '72 so the fuel plumbing may not be identical to earlier versions.
So are the other rubber lines back there clamp-on, and can he use standard rubber fuel-injection hose from an auto-parts store?
Thanks in advance.

Happy Motoring, Mark
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Old 01-24-2018, 02:26 PM
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I'm unclear. Are these cars for sale (if so, price?) or are they cars that you are looking for help fixing....?
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Old 01-25-2018, 01:54 AM
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Quote:
Originally Posted by ScooterABC View Post
I'm unclear. Are these cars for sale (if so, price?) or are they cars that you are looking for help fixing....?
Looking for help. Not for sale, and hoping to avoid a 'fire-sale'!

Happy Motoring, Mark
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Last edited by Mark DiSilvestro; 01-25-2018 at 02:50 AM.
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  #4  
Old 01-25-2018, 09:54 AM
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Regarding the second car, the W108 280SE - here are two diagrams and a parts list. You want to have the battery disconnected when you work around this stuff. There are two possible fuel hose sizes, and gas is going to want to pour out of the tank when you remove the hose, so plan on having a temp hose with a bolt in the end to use as a tank plug. The tank has TWO hoses - forward and return - and they are (as I recall) different size hoses. Maybe 8 mm and 10 mm. See attached pics and send them to your friend and see if this helps.
Attached Thumbnails
A pair of leaky '72s-mb280fuelpic1.jpg   A pair of leaky '72s-mb280fuelpic2.jpg   A pair of leaky '72s-mb280fuelpartlist.jpg  
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  #5  
Old 01-25-2018, 10:11 AM
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Most of those lines end up being metric, so he will need to find a supply of the size he will need, all lines are easy to replace but will need appropriate fuel line clamps ( not the regular clamps as they can cause issues during the clamping process . a vacuum line should not have fuel in it for obvious reasons. I suspect the carb is "sweating" or leaking between the bowl and base. Has it been rebuilt?

Hope that helps and BTW , fuel leak over the manifold although concerning will evaporate the fuel rather than ignite, the flash point is over 500 degrees , oil on the other hand may ignite with flash points of 400 or less.

Of course I never tested this theory
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2011 Porsche Cayman - Bond,James Bond
99 E320 THE Queen Mary
62 220b - Dolly - Finally my Finny!
72 450SL, Pearl-SOLD
16 F350 6.7 Diesel -THOR
07 Lexus RX 350 - Lexi
14 38HP John Deere 3038E Tractor -Mean Green
84 300SD, Benjamin -SOLD
71 220 - W115-Libby ( my first love) -SOLD
73 280 - W114 "Organspende" Rest in Peace
81 380 SL - Rest in Peace
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Old 02-05-2018, 02:58 AM
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Quote:
Originally Posted by meltedpanda View Post
Most of those lines end up being metric, so he will need to find a supply of the size he will need, all lines are easy to replace but will need appropriate fuel line clamps ( not the regular clamps as they can cause issues during the clamping process . a vacuum line should not have fuel in it for obvious reasons. I suspect the carb is "sweating" or leaking between the bowl and base. Has it been rebuilt?

Hope that helps and BTW , fuel leak over the manifold although concerning will evaporate the fuel rather than ignite, the flash point is over 500 degrees , oil on the other hand may ignite with flash points of 400 or less.

Of course I never tested this theory
Well, I spent most of last Thursday replacing fuel lines and other items near the gas-tank of that '72 6-cyl. 280SE.
The 3/8-10mm supply & discharge lines had been replaced previously and were OK
The three original 5/16-8mm fuel return lines were cracked and seeping.
I used fuel-injection hose, even though this electric pump is really not that high pressure - and new fuel-injection clamps - not the cheapo worm-drive ones.
No more active dripping from the return hoses.
Then, with the key on, discovered fuel also seeping from the pump itself!

Mike handed me his spare, used pump - and as soon as I installed it and hooked up the fuel lines, the gas just poured out!

So Mike searched online and found a rebuilt pump for something like $2058!!!
and a $78 pump repair kit, which he ordered instead.
Until the kit arrives from the Northwest Coast and gets installed, Mike's SE will be sitting in the driveway, under a car-cover, with a spark-plug clamped in the tank supply hose, and an 8MM bolt clamped in the return hose.

Meanwhile, just in case the repair kit doesn't pan out, I found a couple Holley vane-type electric fuel pumps online from Summit Racing. 3/8" inlet & outlet. 416 or 530 liters per hour @14 PSI.
Original SE pump specs call for 240 liters per hour and .8 - 1.2 Atm.
Has anyone ever found a substitute for these $2+k OE pumps, or any opinions on whether my candidates will work? Thanks.

Happy Motoring, Mark
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Last edited by Mark DiSilvestro; 02-05-2018 at 03:13 AM.
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  #7  
Old 02-05-2018, 11:22 AM
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I ran my 220 on an electric fuel pump without issue until I found a good original mechanical to return to stock, I think you should be fine with an electric fuel pump the trick will be matching specs and keeping the connections to power spark free and fused
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Ron
2011 Porsche Cayman - Bond,James Bond
99 E320 THE Queen Mary
62 220b - Dolly - Finally my Finny!
72 450SL, Pearl-SOLD
16 F350 6.7 Diesel -THOR
07 Lexus RX 350 - Lexi
14 38HP John Deere 3038E Tractor -Mean Green
84 300SD, Benjamin -SOLD
71 220 - W115-Libby ( my first love) -SOLD
73 280 - W114 "Organspende" Rest in Peace
81 380 SL - Rest in Peace
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  #8  
Old 02-05-2018, 12:49 PM
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Originally Posted by meltedpanda View Post
I ran my 220 on an electric fuel pump without issue until I found a good original mechanical to return to stock, I think you should be fine with an electric fuel pump the trick will be matching specs and keeping the connections to power spark free and fused
Most auto parts stores have, or used to have, electric fuel pumps that will work with a carburetor. Typically they're an oscillating or vibrating solenoid operated diaphragm type of pump.

Compared to more modern FI systems, This SE uses a high-volume, relatively low-pressure rotary vane type electric fuel pump.
I think the rotary vane Holley pump I found may actually work if all else fails.
If so, I plan to fabricate any hardware or brackets to install it as close as possible to the way the original pump was installed.

But I'm still curious if others here would do this, or if they've found a better substitute, or would they just suck it up and pay the $2K?

Happy Motoring, Mark
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Old 02-05-2018, 02:24 PM
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Since the pressure is created by the regulator causing restriction, almost any of the aftermarket fuel injection pumps should work. It all depends on the fittings of course. I believe somebody here on the board mentioned using a pump from a VW or BMW. Sacrilege, yes I know but sometimes ya gotta do what ya gotta do.

Where is the regulator mounted in the existing fuel system?
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  #10  
Old 02-05-2018, 04:55 PM
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Quote:
Originally Posted by Mike D View Post
Since the pressure is created by the regulator causing restriction, almost any of the aftermarket fuel injection pumps should work. It all depends on the fittings of course. I believe somebody here on the board mentioned using a pump from a VW or BMW. Sacrilege, yes I know but sometimes ya gotta do what ya gotta do.

Where is the regulator mounted in the existing fuel system?

The injection on the W108 6-cylinder develops injection pressure in the mechanical injection pump, like a diesel. It requires a low-pressure, approx (12 - 16 psi) high-volume supply pump. My FSM doesn't show an external separate pressure regulator on these.

Except for the BMW 2002tii, all the BMWs, VWs and Mercedes 3.5/4.5 V8s have Electronic or CIS injection systems, requiring high-pressure (approx 60 psi) lower volume pumps. I've heard it's possible to swap the electric fuel pumps on those.

Happy Motoring, Mark
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Last edited by Mark DiSilvestro; 02-05-2018 at 05:10 PM.
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  #11  
Old 03-04-2018, 09:05 PM
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Well, the fuel-pump seal kit arrived three weeks ago, but my schedule and weather prevented doing anything until last week. When I got the pump all apart, I discovered the motor's copper brush-holders had become brittle and their securing-tabs had cracked off in the fiber insulator. They both popped loose when I opened the motor!
So, I had to run back to my friend's place to pull his #2 spare pump off the car.
Fortunately, after I got home and had pump #2 apart, I found the brush-holder assembly undamaged.
Unfortunately, I couldn't simply go ahead and reseal pump #2, as it had deep gouges from someone attacking it with a sharp tool, and one of the ears for the rubber mounts was completely stripped!
So I had to carefully drill out rivets to release and transfer the brush-holder assembly.
Otherwise, #2 pump's bottom-cover was actually in better shape, so it wound up on pump #1 as well.
Combining the best of both pumps, I finally had one running, non-leaking pump to install on the SE this afternoon.
The SE started right up and ran fine, with no leaks. But a month of sitting outside in the wet had taken a toll, as the gas-pedal kept hanging up in 'cruise-control' mode, making for some scary driving!
I had to practically hose down some of the accelerator bushings with ATF to free them, especially the one under the exhaust manifold.

Happy Motoring, Mark
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