Vi(ano) 2014 - W639, )M651, EU 5B Engine Overhaul.

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m80

MB Enthusiast
Joined
Apr 26, 2015
Messages
6,107
Location
Derbyshire, High Peak
Car
Viano ex long, 651 2014. S211 646 2009 (till the Gov't drones blow 'em off the road)
I've removed the engine and intend to do 'some' overhaul work to it.
This maybe of interest and use to others with the 639, 651 and even other models, so I'm intending to update as I go.

I'll have questions that many here can help me with and anyone else should feel free to ask for themselves.

My hope is that at completion I can write up a summary, referring back to this thread, and that others can use it to their own advantage.

My 1st conclusion is that this engine is overly complicated and a bitch to work on, certainly in situ. I by far prefer the OM646.

History.
December 2020 with the months grace the Viano failed its MOT on emissions. 3 rev tests the best it could get was 0.39
There was a hint of a puff of black smoke when stationary and revved hard. MOT didn't pick up on that.
Within the month I became aware of sweet smelling white smoke at start up. So coolant. I found coolant within the intercooler at removal. that being on the n/s I concluded it had entered the air route from above, around the intake manifold.

Trying to remove many components in the congested engine bay became unrealistic.
I didn't see that the intake manifold would be possible to remove, and as the EGR feed from the exhaust runs behind the engine, tight against the bulkhead, that too wasn't coming out either.

With other priorities coming out my ears the van sat till I had time.
Now the engine is out, complete with auto box.
I couldn't have done that w/o an engine hoist and a 3 tonne trolley jack (to support the auto box). In fact I've 2 such trolley jacks and the 2nd became useful.
But this is on the drive, with the front of van on axle stands.
 
Good luck. I look forward to reading your updates.
 
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They're likely to be sporadic as those other priorities are still there.
 
My 1st question.

Throttle valve and pipes removed,
EGR removed, then off with the inlet manifold.
So far no obvious signs of coolant tracking into that area.

I now see 2 same style looking sensors, both 3 wire.
they are immediately below the inlet manifold, but into the block, what are they?

They are above the oil cooler.
 
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My 1st hope is to discover where coolant is getting into the air route, and settling in the intercooler below till next start up.

The EGR cooler is obvious, but doesn't seem to be so.. Pressurising the water jacket within and pressure holds.
Same with the EGR mechanism.
There doesn't look to be any passing from the gasket at the rear where the exhaust gasses pass below the coolant, in that elbow manifold, as the coolant goes into the rear of the head.

The head gasket is then the obvious thought. But my thinking is that should this be passing from coolant jacket to a cylinder, that even with an inlet valve open it wouldn't make its way against gravity and out of the inlet manifold - even though the hot coolant would be under pressure.
That much coolant would have hydro locked the engine on the next start up.

So still a mystery, to me at least.
 
Update.

I had to defer removing the head, my E18 Torx was too soft for removing the M12 head bolts. With the engine on blocks and using a 1 meter scaff bar extension to my 1/2" drive breaker bar I cracked a couple of bolts, then the Torx socket became like butter. Ground down it failed again.
Today a set of impact Torx sockets arrived and so with loads of force, while trying to stop the engine rotating on the blocks , they're all out.

Understanding this engine will hopefully remove my apprehensions of using it for the long term. So yesterday I spent identifying all the sensors+. I'm aiming to know which sensors are where and their accessibility should they go t's up.

The 2 sensors I asked about previously are the knock sensors, not readily accessible, but I haven't read of them being an issue so maybe I can overlook that.

I've started to identify the wire colours that will lead back to the ECU. Then knowing which pins they are associated with might be of purpose in checking for known values with a DVM at a later date, if needed. While I realise that iCarsoft can interrogate much I've learnt that it isn't 'all there'.

I took the injectors for testing. The 1st 2 failed, one failed to build pressure, the 2nd had a sticky solenoid. At that I stopped the testing and asked for the 4 to be refurbed.
The chap took £20 cash for testing and £648 for the refurb's. They were posted back and arrived earlier.
He is happy to recode for free, as apparently the machine assigns new codes. As he runs an MOT station also I'm aiming to book it in for that and have the coding done at the same time.

More later if there's interest.
 
The chap took £20 cash for testing and £648 for the refurb's. They were posted back and arrived earlier

That’s showing some real commitment. If i spent that amount of cash during a refurb id feel absolutely obliged to see it through.
 
That’s showing some real commitment. If i spent that amount of cash during a refurb id feel absolutely obliged to see it through.
I viewed it as saving what should have been a further £15 each.
2 down I guessed the other 2 would 'ave been similar.
 
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I viewed it as saving what should have been a further £15 each.
2 down it guessed the other 2 would 'ave been similar.

That’s good man-accountancy.
 
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Head off and stripped.
A pal owns an engineering workshop and last Saturday we pent an hour or so checking the head for any undulation.
A DTI above, set to zero when in contact with the head, his machine bed can then be motorized to draw around the mating surface (head upside down). Worst we saw was .03mm, and that was in some part due to corrosion where the gasket doesn't sit.
So happy with that.

I've bought a head gasket kit, that includes lots of gasket ++. It's an Elring kit that had good reviews.
I bought a valve spring compressor
but the legs were too big to get in there, legs off I just pushed down and released the collets.

I've just finished putting all valves back and for that I shortened one leg and with 2 bends hooked it under the head casting. Awkward and fiddly job but with a little grease for the collets to stick to the valve doable.

There is a special tool to remove the old valve seals. I persevered with pipe gips, pull and twist.

The valve springs are different for inlet and exhaust, and colour coded. I notice 2 springs on each were swapped. So the head has been off before.

Valves lapped, head cleaned down thoroughly with white spirit, a touch of grease to push new valve seals on, and the head is ready for going back.

I confess that while bending the compressor leg, it being hardened it snapped, pinged off, and knocked my waiting and organised valves.
Now I couldn't be that 3 exhaust valves were in order, so I lapped them again. 2 didn't want to lap so I swapped them and then they did.

Anyway the head gasket is a multi layer jobbo, I believe they are applied dry so that's my intention, Head on no sealant.

The head bolts measure at over 2mm shorter than their max allowable length so I'm intending to re use those.

I've used Henry lots with push on sleeves to create narrow tubes, for vacuuming bolt holes, fiddly corners.... especially after cleaning threads with a flat ground onto an old bolt.
 
When i dismantle multi valve heads i use a discarded plastic egg box to keep things in their respective position. I number each compartment with indelible felt pen. Then each compartment receives its respective parts, valve, bucket, shim whatever. Doesn’t stop you knocking the whole thing off the bench but an improvement on loose storage.
 
When i dismantle multi valve heads i use a discarded plastic egg box to keep things in their respective position. I number each compartment with indelible felt pen. Then each compartment receives its respective parts, valve, bucket, shim whatever. Doesn’t stop you knocking the whole thing off the bench but an improvement on loose storage.
Similarish,
the valves were re assembled with impact shim, spring and to collet thingy. Then lined up in a tuppaware awaiting me to find time.

Collets, all same, another tuppaware.
Followers lined up in another, even though all the same,
lifters same.

The head's on, and tightened. I added a little sealant at the timing chain end that's held down by 3 bolts at 20 Nm
Now to rebuild with all that above gubbins.
I've not got a cam holding tool so we'll see if re assembly of that can be done w/o.
 
Similarish,
the valves were re assembled with impact shim, spring and to collet thingy. Then lined up in a tuppaware awaiting me to find time.

Collets, all same, another tuppaware.
Followers lined up in another, even though all the same,
lifters same.

The head's on, and tightened. I added a little sealant at the timing chain end that's held down by 3 bolts at 20 Nm
Now to rebuild with all that above gubbins.
I've not got a cam holding tool so we'll see if re assembly of that can be done w/o.

sounds like good progress. Good luck with the cams.
 
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Re installing the cams was no issue as it turns out.
I've questioned the value of the cam holding tool and still do, but others with greater experience will likely point out the value.

Engine TDC, old style of feeding a long stick (or similar) down the injector hole. to confirm that
Feed the chain over the camshaft gears, with them aligned with the hexagon hi point in line with the cam back bearing timing arrow.
Front and rear cam bearings were nipped down to level the camshafts.
The chain tensioner then inserted and tightened.
I could see the exhaust shaft was out by 1 tooth, so out with the tensioner, off with the cam bearings and that shaft rotated inside the chain.
Bearings back, tensioner back and was then inline.

I rotated the engine and all was still good, so reinstalled the cam bearings. The head and bearings are stamped with matching letters so they only go back as was removed.
 
The rebuild from then has been slow, because I'm identifying sensor wiring and resistance readings as I go.
I'm also attempting to create a list of procedures for getting to and replacing various components.

For example I see removing the vacuum pump should be feasible from below. 2x E10 bolts and that is unbolted.
That should give access to the HP fuel pump above. That is held by 3x E12 bolts.
That sounds simple and in practice would be far from as easy. So I've taken photos here and there.
 
Too late to edit post 14,
but I came across this on't tother side, very useful and an easy way to check valve timing.
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I viewed it as saving what should have been a further £15 each.
2 down I guessed the other 2 would 'ave been similar.
I also made the decision with mine not to bother testing, the vehicle had done over 325000miles but I bought brand new genuine ones from PFJones £162 each
 
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I also made the decision with mine not to bother testing, the vehicle had done over 325000miles but I bought brand new genuine ones from PFJones £162 each
Sounds like good value,
is that the same engine?
 
It's back in, and I consider it to be a slog.
While I had no intention of rushing I didn't expect so many bits and bats.

No warning signs, although iCarsoft doesn't wish to read it thoroughly, it started 1st time after a while.
The trouble us switch off and it takes just as long to re start.

1st thoughts would be air in the fuel lines, but having run it for a while and revved some I wouldn't expect the air to enter and cause the fuel to return so fast.

No smells of diesel, no signs of leakage.

I got all covers on in time for the rain, so I'm inside for a while anyway, thinking time in hope I get a aha thought.
 
It’s always a relief when a rebuilt motor fires up. Sounds like you’re almost there. Can’t suggest much for your problem but i’ll be cheering you on from the sidelines.
 
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