Has anyone thought to look at the check valve on the fuel water seperator at the fuel inlet line? I have seen these get stuck open, or get trash in them, and cause a lost prime condition.

We run 4 Mercedes engines, and all have had head gaskets before 200k miles, turbos on all four, idler pulleys, fuel rail leakage behind the plastic cover that reads Mercedes Benz on drivers side, exhaust leaks, oil filler tubes replaced (pre-EGR engines), and a busted clutch housing caused from too short motor mount bolts from the factory.

Ours do run quite well, pull good, and get around 6.75 to 7 mph, which is great for what we pull, and where we pull it.

I would hate to pay for the maintenance on these things though.

The EGR engines we use when ours are in the shop only get 5.8 to 6.3 MPG, and have less power. These engines are all going through head gaskets before 200k also, and the leasing company has around 100 of them I think. The EGR system has exhaust leaks also.

The engines have good low end grunt for a 12.8 liter, run out good, but lack severely in reliability.

The US version of the Mercedes engine is totally different from the European from what I understand.

 

My friend has the Mercedes in one of his 2005. It had a total power loss, and was getting difficult to start.

The problem was the fuel filter. There are "two" fuel filters on that motor. They changed it out and all was fine.

And that was after 5 days in the shop, 3 at Freightliner, and two at the Detroit shop, who put the truck on the dyno. That is when they discovered this second fuel filter.

My friend was pissed to say the least, a stinkin fuel filter that no one even knew was there!

 

fuel inlet restriction test takes only a few minutes to perform... most technicians are smart enough to start with the basics --- that thing would have showed massive restriction.

 

I know, my buddy could not believe it went as far as it did. But like someone else said, there is not a heck of allot of knowledge regarding these Mercedes motors. And the truck was on a regular service schedule, and that one fuel filter was never changed in almost a year. It was the one put on at the factory!

 

That's my point... you don't need to know anything about MBEs (which, I don't either) to know that inlet restriction and fuel pressure are primary steps in engine driveability diagnoses. The only people that end up in the scrape you just described are those who fail to check the basics.

The funny part is; next time they have a similar problem (or, any problem at all) with an MBE, they will immediately look for that fuel filter and change it WITHOUT any checks to warrant its replacement.