Viano 722.6 Slipping and Vibrating

[M80]

As per title,
I can feel intermittent vibrations and when cruising at a little less than 60mph the revs rise from 1750 to approx 1950 for a second or two, vibrations can be felt, the revs then fall back and the vibes disappear.
Consumption is less than I would have hope for but as I've not driven far in this, new to me, Viano I don't know what is usual for it.

So a little research and the lock up solenoid seems to be the likely culprit, but other suggestions are more than welcome.

Is the lock up solenoid mounted on the conductor plate or is it within the TC on these?

 

[M80]

Is the lock up solenoid mounted on the conductor plate or is it within the TC on these?

Any thoughts anyone?

 

[M80]

My research wasn't coming up with anything so I rang JPAT for advice, due to them being well praised here. Very informative and useful chat, I'm glad I rang.

My fault is the TC slipping.
There are no electrical components within the TC.
The cause could be the ATF breaking down,
the lock up solenoid faulty,
or the gearbox ECU sending a signal at the wrong time to the lock up solenoid, that is the ECU is confused and maybe faulty.

A star diagnoses is suggested, no surprise there.

 

[LostKiwi]

Didn't we have a similar symptom earlier that @steve@avantgarde diagnosed correctly as a lock solenoid?

 

[M80]

I've read a few threads and attempted to find info elsewhere on't web, so I came up with the solenoid as being the possible or likely culprit. I had also read of the ECU being a possible and scary culprit.
I rang an Indie to book in for a gearbox service and replace the solenoid, since we would be in there changing the filter anyway. I was talking solenoid, the Indie was hearing clutch and suggested that it may be in the TC so hence my coming here for clarification. JPAT gave clarification on that and stated the other possible causes, some more greatly appreciated clarification.
JPAT believes a star diagnosis could identify if the solenoid as faulty, I wondered if so as I can see how it would measure for coil resistance and even the 12 volt trigger, but more difficult to see if the plunger has restricted travel.

In my clumsy attempts at diagnosis I swapped the ECU from Vito (still here) to the Viano (same g'box), it didn't run too well with that, it wouldn't go above 3rd gear, diagnosiswise it certainly wasn't serving purpose.
So thinking it was a different ECU for the more powerful engine, couldn't see why but grasping at straws, I bought one off ebay with matching part number, it arrived this morning, it runs as did the Vito ECU. Speaking to said Indie again he confirms they are coded, can't be recoded, so it's a brick. I had already considered the possible waste of effort here but as the terms of the seller are effectively sale or return my loss is return postage.

Said Indie can't find time to do a service till 9th November, but could possibly do a star diagnosis earlier, which should at least allow me to plan the next move. He doesn't have ability for software updates should that be required though.
I have been considering an icarsoft, is this sort of diagnosis within its capabilities?

 

[M80]

Update, on my attempt at diagnostics.

iCarsoft MBll shows the lock up clutch to go from open at stand still to slipping, no surprise.
The slippage is reported to be 70 to 100 1/min generally, when it rises to around 200 there is vibration. It can fall back to numbers below 10 and is then smooth running, for the short while it's down there.
When cruising in top (should be any gear) I would expect slippage should be near enough if not zero?
I can see that this diagnostic tool will take some learning by my simple mind.

JPAT suggested the ATF could be breaking down, could even have glycol contamination, although as we know that is far less likely on a 2009 vehicle. His suggested 'roadside' test was to put a little of the removed ATF on a teaspoon, heat it and if it steams there is glycol (well water within the glycol).

As I stand the possibilities are as said above, plus the added 'possibility' of the local garage as used by previous owner having put in the wrong ATF (I've seen some evidence of non conscientious work and prior to that all works were by MB main dealers).
It may be the TCU, but I would prefer to eliminate other more obvious causes.
The lock up solenoid may be faulty, and / or I suppose the conductor plate.
As at this stage as I don't know if the TC will be going off for a recon I considered to change the ATF and monitor for improvement.

My intention is to change 5 litres. Having replaced approx 5/6 of the ATF with new and correct ATF if that's the problem I should see improvement. Later having used the 5 litres to flush I would then do a full filter +++ service. If this 5 litres makes no change I would assume the issue is elsewhere.

I put some old ATF in a cleaned bean can and heated on the gas cooker, there were vapours but maybe the heat was too much and may well have caused the oil to give of some vapour?
I now have 1/4 litre of the old ATF in a clear plastic container, stood on a radiator, to see if there is separation of any water content from the oil. It can stand there for a few days it makes no difference to what I'm doing so far.

Comments welcome.

 

[Steve@Avantgarde]

Just seen this thread so apologies for the late reply!

The lock up valve chatters in operation, its more noticeable when cold due to the oil being thicker and it being in use more as the gearbox is cold. It usually improves as it gets warmer. I

The lock up valve is on the valve body. If you have had electro plates apart before, you will be able to replace the lock valve yourself. Its the most forward valve of the 2 on the left side of the EHCU.

I wouldn't say you have glycol contamination, neither would I suggest your gearbox oil is breaking down, these 5g gearboxes can run for 100k miles + on the same fluid, not that it is advised. It is pretty impossible to put the wrong oil in these boxes, the spec oil is Dextron 3, which is pretty much standard ATF. Spec changed on the later boxes to the ATF134 fluid, but if your car/van is pre 2007 it would have had DX3 from the factory.

In the case of the other forum member that was mentioned, no one previously had checked the fill times of the adaptations, that is the biggest clue if you have a mechanical issue or slip inside the gearbox, the fill times will rise indicating a loss of hydraulic pressure through one of the clutch packs. If you haven't done it I would advise you do.

 

[M80]

Thanks Steve, any input is appreciated, whenever.

The fill times is somewhat over my head, can these readings be found with the iCarsoft do you know?
Is the slipping / vibrating having any long term detrimental effect with continued use?

While I'm in there i'll drop the valve pack to see if anything is obviously amiss, if nothing else it may improve my familiarity.

 

[Steve@Avantgarde]

Sorry Martin, I am in no way familiar with Carsoft, I use STAR.

It will probably do damage to the friction plates on the TC, that is a speculative guess tho.

 

[M80]

I'm not surprised you're not familiar with iCarsoft, but thought I'd ask.

When I dropped the sump the Chinese filter was loose and came away with it rather than being held and requiring to be unclipped.
In hope, could this cause a drop in pressure and hence the problem?

 

[M80]

As expected Steve, new oil and no difference.
Looking at videos of valve pack removal it is clear that it can be a little more complex than is safe to do lay on my back using axle stands.
The garage needs a reorganising clear out before I can be sure to keep the components forensically clean, so the valve pack stayed in.

So fill times of the adaptations and knowing what that means is down to some one like you Steve methinks.
All I can be fairly sure of is that the TC lock up clutch is slipping.
On a hill when it's slipping that can be reduced by application of the right foot, so relating that to a manual's slipping clutch I would view that it isn't excess wear of the clutch but a lack of hydraulic pressure. So back to the lock up clutch solenoid, or the valve it operates.

Maybe.

 

[Arudge]

The fill times is somewhat over my head, can these readings be found with the iCarsoft do you know?

Fill times and adaptations are only available on STAR. When your working on this level you'll quickly realise just how basic icarsoft and carsoft actually are. They are little more than code readers, STAR is a diagnostic tool, completely different animal.

 

[Arudge]

While I'm in there i'll drop the valve pack to see if anything is obviously amiss, if nothing else it may improve my familiarity.

You're not looking for something obvious. If Steve is right and your looking at a worn spool valve (the lockup valve) then the amount of wear will be measured in microns. Just to add insult to injury, you'll need to clean the valve block of every trace of oil. it's usually the valve body that wears as it's only aluminium, the spool valve itself is steel.

Some light reading for you.

https://www.sonnax.com/vacuum_testing


An exploded view of what you have and the available repair kits.

https://d2q1ebiag300ih.cloudfront.n...0/Mercedes_722.6_Interactive.pdf?v=1488909158

 

[M80]

We took the Viano down to London on Saturday, a round trip of 330 miles.
The slippage is now much better perhaps showing an accoasional slip of 75 revs on the rev counter, I can just tell by feel but only just.
Occasionally the slip is more and the vibes similar, torque related I believe. So the ATF change has had a positive effect it just took a while to work through and clean components ??

Another symptom that I thought was the lock up clutch, but now question that, is that there is a slipping clutch effect when pulling away.
If I take revs to 2K the Viano doesn't pull away with gusto but pulls away casually as the vehicle speed catches up to the engine speed. I can get it to go with enthusiasm by using more revs.
The improvement to the cruising slippage hasn't made a difference to the pull away slippage.

 

[Doug1234]

The teaspoon and atf /water will give steam I suppose but a better method is used when checking vegetable oil for water contamination before putting in the fuel tank !!!!, is to drop that teaspoon of oil into a very hot frying pan and any spitting or hissing means water is present.

 

[M80]

Thanks for that,
my sample has been on the radiator for 3 days with no evidence of separation. It looks good to me, but there is no rush to move it.

The most prominent symptom now is the slippage while pulling away. Understanding what slipping or why is possibly the key.

 

[Arudge]

The TC lockup clutch doesn't engage at lower RPM. If i find time I'm sure I've got a chart showing when the clutch starts to engage and when its fully locked, you shouldn't feel it when in operation, unless it's faulty of course.
Most slipping is down to worn clutch packs but that's a full strip to ascertain. A session on STAR is less invasive and should give you a fair indication of the condition of the internals.

 

[M80]

The TC lockup clutch doesn't engage at lower RPM. If i find time I'm sure I've got a chart showing when the clutch starts to engage and when its fully locked, you shouldn't feel it when in operation, unless it's faulty of course.
Most slipping is down to worn clutch packs but that's a full strip to ascertain. A session on STAR is less invasive and should give you a fair indication of the condition of the internals.

I assume that's the clutch packs within the auto box itself?
How similar are different 722.6 boxes, would a replacement have to come from a V6 Vito / Viano?

 

[Arudge]

I assume that's the clutch packs within the auto box itself?
How similar are different 722.6 boxes, would a replacement have to come from a V6 Vito / Viano?

Yes, and Ohhhh yes.
Within the 722.6 range there are at least 50 variants, although only two gear ratio variants. As for the gear ratios there's a build for everything up to and including V6, and everything over. The main differences lie in the clutch packs, of which there are six. A clutch pack may have three plates, or five. They may be single sided friction plates or double.

In essence, Mercedes have tweeked the transmission to suit every different power and torque curve, which is why we have so many variants. Each clutch pack is built to suit the power and torque output of the engine bolted to it, and in your application a load carrying capacity as well.

If you fitted a brand new transmission built for an E200, then sure it would work, but it would never handle the torque output of the V6 and would probably start slipping with half a dozen empty cardboard boxes in the back.

Sorry it's not what you want to hear, welcome to Mercedes.

 

[M80]

Arudge, that's as I expected. well similar response anyway.
Of course if the same box went in to so many vehicles picking up a good 'un at a reasonable price would be easy.
Thanks again, now I know that I need to be specific with a search or get this one refurbed, that's probably favourite after a Star check confirms what seems reasonable to expect.