My 87 W201 turbo diesel has been sitting in the garage for about two weeks. Yesterday I went to move the car and discovered a large puddle of fuel on the garage floor. The puddle is directly below the IP pump. Both the supply and return fuel lines show no indication of leaking. The lift pump also seems fine.

The leak(s) appear to be coming from the IP pump where the hard lines connect into the pump.... however I'm not 100% sure. At the very least, the top of the pump is wet.

Anyway, is this a case where the delivery valve O-rings have perished?

Could be, but have you checked your fuel thermostat for leaks? The DV o rings don't generally leave a puddle, but the thermostat does.

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I have a spare, with fresh o rings if you need one.

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I forgot to mention, the fuel thermostat was removed from the system a few months ago.

Delivery valve seals could be the culprit. But a really big leak suggests a broken hard line. They tend to break right above the ferrule. What you want to do is clean everything with brake cleaner and the run the engine until you spot the leak.

I'll take a better look at the hard lines tomorrow evening. Thanks!

The pump diesel here fluoresces weakly under UV. A UV light was cheap on Amazon and was handy looking for leaks, the green glow will help you find a leak faster than you can see it by bare eye.

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Amazing tip

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Don't forget to grease the screw and threads on the spring compressor.

I went ahead and sprayed brake cleaner all over the injector pump and side of the block. After about an hour the area was all dried up.

The picture is a 'dry shot'

Anyway I ran the engine for about 1/2 hour and the IP was still dry. Hmm
I reckon I'll let it sit over night and take another look.

[IMG][/IMG]

Check your motor mounts same color hydralic fluid.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

So the car has been sitting 12 days since I last started the engine. The huge puddle of fuel has re-appeared.

[IMG][/IMG]





Seems like a lot of fuel...



The delivery valve holders are wet...




The top of the motor mount is wet...

The fuel lines are dry on surface, the lift pump is dry is dry on surface

the car starts up about the same, hard to tell because of the cold weather.


Any ideas?

Injector hard lines may not be seating properly on top of the delivery valves
(allowing fuel to slowly leak out of the hard lines when the car sits for a long while).

The number two hard line in particular looks askew.

White tissue paper is ideal to use for a touch test to find those hard to spot fuel seepage locations.

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Hmm, based on your suggestion, I think I'll try an experiment.

if the DV's or hard lines are leaking then tissue paper around these parts should wick up most of the fuel before it leaks on the ground....

The car is off the road for the rest of the winter so I have a few months to sort this out.

Might be worth a check of the clear (probably brown now) line on the backside of the IP back up to the filter housing. If the banjo bolt is loose or the line is cracked, it's possible for fuel to leak out under gravity through the return line.

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How does the fuel filter look? Could be a leaky filter seal or bad o-ring. Also, check the backside of the IP.