Fuel Leak- Where is it???

Hey everyone,

I have a fuel leak on my 2005 3500, which is dripping on the left side of the engine compartment. I've only seen suggestions to check around the fuel filter and pump, which are on the right side. I've checked all around the high pressure pump on the engine block and can't feel any leaks. It's at the point now where it's dripping several drops a second.

Does anyone have any idea or images of where the fuel lines go on the left side of the engine, and where there might be a leak?

Thanks in advance for the help!

High pressure fuel pump. The bolts that hold it together come loose / fall out and starts to drip fuel above the alternator area. Usually when it's cold


Howboutcha-

Dr.A TECH ALERT-647 High Pumps
As many 612 owners have discovered, '02-'03 612 Sprinter high pressure pumps are prone to degradation of internal seal elements of which there are many. The result is external fuel leakage along the front of engine. I have offered an economical rebuilding service for these 612 high pumps for quite some time.





647 Sprinters ('04-'06) have a very different high pump design. The cast steel portion is now a mono-bloc design which eliminates many of the seals that degraded in the earlier 612 pump design.





The 647 pump has a separate aluminum base console (flange) which houses all the passage ways and control elements for fuel metering into the pump and for return flow out of the pump.





These 647 pumps are increasingly developing external fuel leakage (similar symptoms to the 612 pump leakage). Unlike the early pump's high pressure leakage this is feed pressure leakage but just as troublesome.





The cause appears to be gradual loosening of the 6 internal socket head (Allen) bolts securing the aluminum base console to the steel pump body. Dissimilar material expansion, heating and cooling cycles and vibration are the challenge here.These 6 bolts are accessible only from the back side of the (removed from engine) pump.





When these bolts loosen, an internal array of seal rings develop leakage and fretting typically occurs between the pump and console castings.





An emergency fix involves re-torque of the bolts but the more reliable fix is professional disassembly of the pump and replacement of all internal seals after refacing the affected surfaces and reassembly using bolts with locking agent.





I offer this service to 647 owners at a significant savings from factory rebuilt. Contact me directly for details. Doktor A
https://sprinter-source.com/forums/showthread.php?p=94784


Howboutcha-

Fuel smell in cabin on startup
Here are some pictures of the bolts falling out of the high pressure pump





Sent from my iPhone using Tapatalk
https://sprinter-source.com/forums/showthread.php?p=341689


Howboutcha-

ya i've got an 06 check your high pressure pump anyways for bolts coming loose but my leak was on the suction lines going to the HP pump, needed a new O-clamp and problem solved. Fumes are from diesel cooking on the block

Wow, thanks for the thorough response, much appreciated. Will investigate today.

Hi there,
There is a drain pipe from the 'trough' in the head where the injectors are mounted, this is an escape route for any diesel leaking from the bleed off pipework, from injector unions, or blow-by caused by failed injector sealing. This 'drain' emerges from the back of the head and connects to a rubber hose that exits lower down the block. Chances are if the front of the engine is obviously 'dry' of diesel, you will have to lift the injector cover and take a peek underneath and see if the source is from under there - causes above.
Regards
Steve

Still trying to hunt down this leak. Went to the shop and was told that it is coming from the fuel filter- pretty disappointed with the diagnosis because it was obviously not coming from the fuel filter. Still, bought a filter, and now that the filter is changed out it seems that the leak has increased. No signs of fuel leaking by the filter, it all seems to be coming from just above the alternator. It's dripping all over the oil pan and alternator, etc but not on belts. Was thinking it might be the fuel return line but I can't feel it or find it anywhere despite the drawings in the service manual. I've ordered the fan removal tools listed made by jackbombay, and will try to pull the fan to allow access for pulling the high pressure pump.

I checked around the injectors and found no obvious leaks. Could the drain mentioned in the post above be that efficiently draining leaking?

Many thanks for the thoughts and ideas.

Above the alternator ? High pressure pump. When the engine is cold , start it up and look to the left side of the pump for the fuel drip


Howboutcha-

Yep, that's what I'm thinking. Can it be pulled without removing the radiator? Just picked up the special fan removal tools.

I did mine without pulling the radiator. I did take the top radiator support brace off so the radiator moved slightly towards the front.


Howboutcha-

Yep I didn't 'need no fancy fan removel toolz mmmhmm

If its leaking several drops per second, should be easy to locate right? Take the plastic cover off the top of the engine.

Shouldn't have to take the cover off unless your checking injectors


Howboutcha-

I'm guessing that those of you who didn't pull radiator pulled the fan? Doesn't seem possible to squeeze hand in on the t1n to reach the bolts holding in the pump.

Thanks for the thread, I was able to fix the leaking pump on my 2006. Now don't make my mistakes. Take the stupid belt off, made getting to the bottom bolt much easier. And then, don't put the stupid belt back on. Diesel fuel and rubber don't mix well, I had to do a roadside belt change the next day. Thanks again.

tgoods said:

Thanks for the thread, I was able to fix the leaking pump on my 2006. Now don't make my mistakes. Take the stupid belt off, made getting to the bottom bolt much easier. And then, don't put the stupid belt back on. Diesel fuel and rubber don't mix well, I had to do a roadside belt change the next day. Thanks again.

Click to expand...

I'm going to give this a try on my leaking 2006. what is the belt that should be swapped that tgoods speaks of?

lance_k said:

I'm going to give this a try on my leaking 2006. what is the belt that should be swapped that tgoods speaks of?

Click to expand...

I believe he's talking about the main serpentine belt, and what he meant was that you're going to want to put a *new* belt into place, instead of expecting the old, fuel-damaged, belt to provide any useful amount of further service.

--dick