Tech Alert- 647 Hi Pump leakage

I have been getting lots of calls on the subject of leaking 647 hi pumps lately.

I suspect my earlier Tech Alert has been difficult to locate using the group search function, so here it is, in an updated version:

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 (Torx) 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.

A simple test is to turn on ign with engine cold and check for leakage at the high pump while the electric supply pump is running. The electric pump operates for approx. 30 seconds with each ign key-on cycle.

In many cases the fix involves re-torque of the bolts. In some cases the more reliable fix which I recommend 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 advice.

Doktor A

abittenbinder said:

...

Contact me directly for advice.

Doktor A

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"Call my Sprinter Hot Line 864-623-9110."

(For those new owners who may not know.)

I can't find the entire thread but I printed it yesterday. Noticed what I believe to be diesel fuel under the passenger side of the engine in the front. Looking up it appeared to be coming from under the high pump. Drove (completely up to temp) and the leak appeared to stop. Engine expansion I suspect. That dog has bitten me before, cold vs hot leaks. Left it at a shop and they are unable to determine the origin. The rig was backed up on a sloped driveway with the engine on the "low" side. Would this affect the leakage? I hate spending money, is it better to be aggressively proactive on this or wait till it reveals itself again?
Thanks

By the way, is there a way to enter a thread number directly into a search to get back to the same posts? It was thread # 11354 I believe. I followed a link originally.

Thanks for the information.
My 2006 had the same symptoms of leaking when cold.
I pulled the pump and the bolts were tight, but I removed them and appplied locktite.

There seems to be a small leak near the two hoses that come out of the pump. It looks like there are two little holes (horizontal) between the top and bottom hoses. It doesn't look like the hoses are leaking but it is coming from the hose area. Before I tear it apart again I was looking for some input from you all.

Thanks
David

I've replaced the supply and return hoses on the HP pump on my 06 at about 100K miles. the rubber itself seemed to be deteriated? allowing a fuel seep from under the clamps. new hoses seem to have cured the leak.

Bob

P.S. do it at a oil change, it's much easier to do with the oil filter cap removed.

Thanks I'll give that a try.

This post and a call to Doktor A Saved the day.. Not to mention all that MONEY..
Thank You Doktor A

Thanks for the tips. I could see where mine was coming from, removed the pump.. 2 of the bolts fell out and 2 were finger tight..unreal.. loctite..reassemble.. no more leaks. Tricky to get to that bottom bolt though..lol

Yes a big THANK YOU is in order for Doc A!!!! I called Doc before buying, he graciously returned my call ave me the run down and I in turn relayed the info to a mechanic that was recommended to me, he made me sign a waiver saying he wasn't responsible but I figured that $130 was a better starting point than $1700-2500 that was quoted by various shops and the dealer. Picked it up yesterday and she runs beautifully, except a coolant leak that developed, hoping it was something to do with replacing the serpentine belt, crossing my fingers.

Hello all, my HP fuel pump leak ended up being from the lower suction line coming from the fuel filter. Needed a new clamp. But for good measure I took off the fuel pump and checked all the bolts...none had backed out, but this is a 2006 sprinter 2500. Locktite'd everything, put back together. Gas mileage is awesome now that fuel isn't pissing on the ground!

i have an OM612 and the top cap is leaking on my high psi pump is leaking fuel. I purchased the seal kit for it however I can't login to WIS-net on my Mac computer to locate service instructions. I just need to know torque specs if at all possible. thanks so much!

Mine started leaking yesterday, but it is a bad leak. It leaks with the ignition on before starting, so it is low pressure side. I drove it to work today, but probably should not have as it is leaking all over the serpentine belt and my new alternator. I will try to remove/re-tighten tonight. Should I use Red or Blue Locktight?

PATECO said:

Mine started leaking yesterday, but it is a bad leak. It leaks with the ignition on before starting, so it is low pressure side. I drove it to work today, but probably should not have as it is leaking all over the serpentine belt and my new alternator. I will try to remove/re-tighten tonight. Should I use Red or Blue Locktight?

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The color (type) of locking agent is actually less important than the cleaning and prepping of the threads. Neither will be effective if threads are contaminated with fuel.

Address one bolt at a time, do not clean the outer pump housing until tightening is completed, use any color you like but be aware the red can complicate future work on the pump.

Doktor A

abittenbinder said:

The color (type) of locking agent is actually less important than the cleaning and prepping of the threads. Neither will be effective if threads are contaminated with fuel.

Address one bolt at a time, do not clean the outer pump housing until tightening is completed, use any color you like but be aware the red can complicate future work on the pump.

Doktor A

Click to expand...

OK, Blue Threadlock it is.

Clean with Carb Cleaner and Q-Tips?

PATECO said:

OK, Blue Threadlock it is.

Clean with Carb Cleaner and Q-Tips?

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Should work. Q tips optional, as fuel will readily flush out with a fully evaporating solvent.

anyone have the part # for the seal rebuild kit for the 647 injection pumps?

I wonder if you can see the oil pan drenched with fuel in my photo. We started to smell fuel yesterday. I didn’t notice leakage around the HP pump with the ignition on, but the smell of fuel was strong. Fuel dripping off the oil pan is what we found.



Could fuel running down the back of the engine be symptomatic of the leaking HP fuel pump?

Engine only has 22k miles & came with a 36k warranty. So we’re at the Mercedes dealer now. Of course it’s Sunday, so hopefully someone can look at it first thing tomorrow.

The HP pump is on the top front of the engine:



2006 service manual: http://diysprinter.co.uk/reference/2006-VA-SM.pdf

--dick

Turned out to be one of those fuel lines. Naturally, it was the one behind the oil filter. But phew, a relief to have that fixed.

The short fuel lines behind the oil filter are a common leak point as the lines get old. Easy fix. A quick field repair is to remove the factory clamp, and install a fuel injection clamp instead. Eventually the line will need replaced though.