Opinions on the 651 engine, in the Vito

[M80]

It's time to move on from the Viano (642)

I've good experience with the 646 engine, in an 07 Vito
and 611, in the C class, pretty much the same as the 646 for working on.

Now I'm considering the possibility of the 651 engine in a 09 / 10 Vito.
I'm hoping for some input as to how easy or not these are to work on.

I seem to remember that a fuel pump is sited to the rear on these, and that was a big problem for removal. But I believe this would be with the engine longitudinal.
Am I correct that in the Vito the engine is transverse, so the issue shouldn't exist?

Is the 651 a nuisance to work on or as easy as the 646?

 

[LostKiwi]

I seem to recall seeing a thread where several Indys mentioned they'd never buy a 651...
Timing chains are an issue and they're located at the flywheel end of the crank.

 

[M80]

Thanks LK, that's the sort of info that's useful.
Sounds a bit like the smaller petrol engines.

 

[LostKiwi]

Here's the thread:
http://forums.mercedesclub.org.uk/index.php?threads/om651-diesel-engine.127811/

 

[M80]

Interesting reading, although not pleasant.

 

[M80]

Not that I would look forward to replacing cam chain tensioners every 40k perhaps,
if I'm right that the 651 is mounted transversly in the Vito it might not be such a great issue??
It does remind me of new camshafts in a Ford o/h cam engine every 40k though, an engineering screw up or revenue generator?

Has anyone done this in the Vito?
Are there other issues with this engine?

 

[alexanderfoti]

Issues with 651:
Cheese water pump
Plastic sump
Plastic inlet manifold that leaks and snaps the bolts holding it in place
Single row timing chain that gives problems on stop/start versions
Plastic thermostat housing
etc

If kept on top of, they run fine, but you need to keep an eye on the above list, basically anything coolant related.

 

[mrmb]

I have W204 with OM651 in C200 version. Just waiting for the intake to come in :-D It is my first issue with this engine since one year ownership and 40 000km. My advise is to reprogram the Start/Stop :-D so it will not be used on daily basis without manually turning off.

 

[Gazwould]

Issues with 651:
Cheese water pump
Plastic sump
Plastic inlet manifold that leaks and snaps the bolts holding it in place
Single row timing chain that gives problems on stop/start versions
Plastic thermostat housing
etc

If kept on top of, they run fine, but you need to keep an eye on the above list, basically anything coolant related.

Great driving motor , just this chocolate flavour plastic backwards engineering issues.

Got coolant and oil leak / loss + other issues .


Sonething an old faithful , 16 year old, 182K motor, hasn't suffered in my 6 year ownership .

 

[curious]

Trying to work out the changeover from OM646 to OM651 in the Vito. Does anyone know when it occurred? Do some of the facelift W639s have the OM646?

 

[alexanderfoti]

Great driving motor , just this chocolate flavour plastic backwards engineering issues.

Got coolant and oil leak / loss + other issues .


Sonething an old faithful , 16 year old, 182K motor, hasn't suffered in my 6 year ownership .

That said........ My mum has had an OM651'd C250 CDI for 7 years and 50k and I have done nothing but servicing.

 

[umblecumbuz]

That said........ My mum has had an OM651'd C250 CDI for 7 years and 50k and I have done nothing but servicing.

So it's the luck of the draw. Sometimes good, sometimes bad.
BUT ... a known weakness is still a known weakness.

 

[alexanderfoti]

So it's the luck of the draw. Sometimes good, sometimes bad.
BUT ... a known weakness is still a known weakness.

Absolutely. I see lots that have issues so...

 

[M80]

Thanks for ll input, I'm suitably deterred.
Choosing the next Vito is diffiucult due to the pro's and cons.

2.1 wins over 3 litre for economy, approx 20% in my experience but that was my Vito 646 pre DPF and all 642's have DPF.
The 642 also has a fair list of issues waiting to bite.

A later 651 can have road tax and fuel economy advantage, but now there are reliability issues, thanks again for the pointers here.

There can be road tax advantage of any heavy lump registered pre March 2006, but this age is pre facelift and there is now an increased likelihood of rust.

Finding a Vito registered as N1 catagory isn't too difficult but finding one with alarm, rear wash wipe, rear parking sensors (at least), and drivers heated seat (at least), (I can instal my own leather seats from an ML later), and rear seat floor rails is a very difficult animal to find. Oh and pre DPF is preferable as with that there are more sensors to throw wobblies, and they do.

The easy route is a Viano with the 646 engine. It can come with all goodies, but high road tax. In fact I have that now but with the 642 engine, and what a bitch that has been.


If the Vito / Viano was reliable the extra complications in design of the newer, DPF included vehicles wouldn't be a problem, but they're not.
I'm looking toward owning something that might need my attention here and there but not as often as I've experienced recently. And a major issue with newer vehicles is their dependancy, not only on specialised diagnostics kit, but a need to have online software updates from the manfacturer for far too many items that might need replacing, sort of reduces the advantage of buying my own Star kit (and that has been another painful story or two recently).

Herbiemercman isn't far out with his recent thread.

 

[Steve@Avantgarde]

651's are great engines for performance and economy, no doubt about it, but its just a pig to work on, meaning any job you have to do can be labour intensive. The later 654 has addressed some of these issues.