I have a '87 124 w/603.96 eng. I don't know what the item is that is leaking all I can do is describe it. It is immediately downstream from the primary fuel filter. It is about 3.5 inches long and has 4 fuel lines attached to it. It is located directly above the motor mount on the drivers (US) side. Is it the lift pump or a valve of some sort? Fuel is dripping out the front where the line from the primary filter attaches. I have loosened and re attached but to no avail. Can it be rebuilt or must it be replaced?

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Muleears
'07 E320 Bluetec 133K my DD
'04 Jaguar XJ8 VDP, 34K
'10 Hyundai Accent 60K Grocery Getter
'02 VW Golf soon to be on the road again
'97 E300 Diesel Son's DD
'61 VERY tolerant wife

Hampton Roads, VA USA

Gone but not forgotten:
'67 250S 95K
'86 300SDL
'87 300D Turbo, 364K! R.I.P.
'98 E300 Turbodiesel, 213K
'02 S420, 164K
'01 Prius 138K

Sounds like the fuel pre-heater...

Follow the two (presumably metal lines) and they should go around the back of the engine where coolant comes from.

Not sure where this would leak from but it is not a necessary component especially if you live in a warmer climate.

Bill

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'87 300SDL, intensely modified Greasecar setup, with nickle plated heat exchanger, 3 valve setup, 312,000 miles
'95 Suburban diesel, Greasecar basics, 16 plate heat exchanger, mercedes fuel lines, Racor filter
'85 Renault Alliance converted full electric vehicle

Two of the lines connect to two metal lines that disappear behind the engine. I live in SE Virginia (near Norfolk). We get some snow and single digit temps on occasion. Do you think I need it or can I just bypass it? If I need to replace, where can I get one? Thanks again.

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Muleears
'07 E320 Bluetec 133K my DD
'04 Jaguar XJ8 VDP, 34K
'10 Hyundai Accent 60K Grocery Getter
'02 VW Golf soon to be on the road again
'97 E300 Diesel Son's DD
'61 VERY tolerant wife

Hampton Roads, VA USA

Gone but not forgotten:
'67 250S 95K
'86 300SDL
'87 300D Turbo, 364K! R.I.P.
'98 E300 Turbodiesel, 213K
'02 S420, 164K
'01 Prius 138K

Mine leaked also, so I bypassed it. Can't really see why it's needed, unless you live in an arctic region.

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87 300D - Running on Veggie oil; 260,000 plus miles; Original #14 head

I don't know if it is worth it. I am sure the price is fair. But I may just bypass it. What will be the downside? A greater chance of gelling fuel in the winter? I can put the $146 toward improving my AC or a paintjob. If it won't start in January I just won't go to work!

__________________

Muleears
'07 E320 Bluetec 133K my DD
'04 Jaguar XJ8 VDP, 34K
'10 Hyundai Accent 60K Grocery Getter
'02 VW Golf soon to be on the road again
'97 E300 Diesel Son's DD
'61 VERY tolerant wife

Hampton Roads, VA USA

Gone but not forgotten:
'67 250S 95K
'86 300SDL
'87 300D Turbo, 364K! R.I.P.
'98 E300 Turbodiesel, 213K
'02 S420, 164K
'01 Prius 138K

No need to bypass; 15 minute job. Remove all the hoses, 2 small bolts remove the cannister. Disassemble and replace the o-ring on the intake side; reassemble, reinstall and drive on.

Jim

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2005 C240 4matic wagon (daily driver)
87 190D - 225K (on loan)
85 190D - 312K (on loan)
2011 Subaru Legacy AWD (Wife's)

The fuel thermostat in most cases is attached to the left side engine mount arm. In some early 87 300Ds it's bolted to the block ahead of the engine mount arm.

The dealer sells the o-ring which is what usually fails causing leaks.

Sixto
87 300D

How does one bypass this thing?

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1995 E420 152k
1991 300D 2.5 348116 daily driver
1992 300E 2.6 196k-work in progress(head gasket)
2002 BMW 745Li 93k

Go from the small filter directly to the lift pump. The lift pump has two fittings - one is a rubber hose with clamp from the fuel thermostat, the other is a plastic line with a crimped threaded fitting (or is it a banjo fitting?). The fitting with the rubber hose and clamp is the input. That's the one you're after.

Sixto
87 300D

Thanks for the reply Sixto. When you are ereferring to the fuel thermostat are actually talking about the pre heater? I've identified the lines. What I don't understand is what goes where. This is for a '91 300D and it has the banjo fitting. Am I suppose to remove the line in front(closest to the engine) of the primary fuel filter and attach it to the lift pump? Secondly, input line goes where? Sorry for all of the questions, but I'm still not really familiar with the fuel supply sytem.

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1995 E420 152k
1991 300D 2.5 348116 daily driver
1992 300E 2.6 196k-work in progress(head gasket)
2002 BMW 745Li 93k

Here it is in graphic form. I hope your 91 300D isn't too different from this 87 300D.

Sixto
87 300D

Attached Thumbnails

 

Is it really that simple? I'll give it a shot right now. The other lines can remain open?

__________________
1995 E420 152k
1991 300D 2.5 348116 daily driver
1992 300E 2.6 196k-work in progress(head gasket)
2002 BMW 745Li 93k

The lift pump has two fittings - one on top that goes to the big filter, one at the end pointing downward from the fuel thermostat/fuel heater. Simply route the hose from the small filter to the lift pump inlet. Either loop or plug the lines to and from the fuel thermostat. Heck, leave them open.

Sixto
87 300D

The fuel remaining in the thermostat/heater circuit will leak out. You can plug or loop the lines.

Sixto
87 300D

Thanks. That was easy enough. Another fuel leak solved. I had grabbed that pre-heater from the local pick-and pull a few months ago. I decided if it had started leaking again that I would just bypass it. Misson accomplished.

__________________
1995 E420 152k
1991 300D 2.5 348116 daily driver
1992 300E 2.6 196k-work in progress(head gasket)
2002 BMW 745Li 93k