Some questions about OM646 longevity

[almoniyot]

I am looking at some 17-20 year old vehicles (W639 Mercedes Vito) with the OM646 engine. Many of these vehicles have done around 250-350k km (150-220k miles). How much is too much for this engine? What specific things should I look at to ascertain the condition of the engine. If I have a pre-purchase inspection done, is a compression test typically part of it? What is the best way to know the condition of the injectors?

Thanks!

 

[Trickythemerc]

OM646 if properly looked after are one of the best Merc engines out there. They can suffer from failed injector seals AKA black death. I have run Sprinters to close on 500k miles without any major failures, regular oil and filter changes will help. A compression test on any diesel is going to be costly as you have to pull the injectors. You can do it via Star Xentry but not sure how accurate this test is.

 

[ALFAitalia]

A derv compression check does not usually touch the injectors....its done through the glow plug holes.

 

[almoniyot]

OM646 if properly looked after are one of the best Merc engines out there. They can suffer from failed injector seals AKA black death. I have run Sprinters to close on 500k miles without any major failures, regular oil and filter changes will help. A compression test on any diesel is going to be costly as you have to pull the injectors. You can do it via Star Xentry but not sure how accurate this test is.

Thanks. Good to hear. I owned a OM648 W211 until someone decided to ignore a traffic light and hit my vehicle. Is the OM646 simply 2 cylinders shaved off? I knew to check for 'black death' on that one before I bought it.
At this age it is probably wise to have the injectors cleaned and checked after I purchase a vehicle.
As someone else noted, compression test is from the glow plug hole.

 

[Trickythemerc]

Senior moment I meant glow plugs but was in injector mode.

 

[Pontoneer]

A derv compression check does not usually touch the injectors....its done through the glow plug holes.

Indeed , but some glow plugs can be notoriously difficult to remove if they’ve been in there a while ; also , on my E250D , the inlet manifold had to be removed first to get at them , as I had to do to replace the two dud ones which were causing poor starting and keeping the warning light on . Of course I replaced all five .

 

[Trickythemerc]

And they are so prone to snapping due to being so thin.