OM642 Power problem.

[tode]

Good morning all.
I have a W221 with the OM642 engine which has given no particular problems in the last few years, but while on a trip yesterday, while cruising at 70 mph I started to notice that the revs were much higher than usual (2400 instead of 1500) - I thought maybe doing a regen, but a few minutes later I could still maintain speed, but there was no reaction when I tried to accelerate (to overtake). Even foot flat on the floor, no increase in revs or speed. No EML. Rather worried, as I had 200 miles of motorway ahead of me !
After 5 - 10 minutes of this, I pulled over, switched off, and waited 5 minutes. Switched back on and set - no problem, back to usual.
A similar thing happened two years ago, but then it lasted two hours and when I took the car into Mercedes, they found nothing - no fault logged under Star.
Has anyone got an idea what's happening? Batteries fine and servicing up to date, no other problems . .
Thanks in advance.

 

[Larkone]

Probably turbo actuator

 

[tode]

Thanks . . . Could you explain a little more . . . all I know about turbos is that they blow

 

[Larkone]

Lots of info here

electronic turbo actuator on the 3.0v6 deisel

bit of conformation am i right in thinking these actuators should flick up and down when the ignition is switched on and is there anything that would stop it actually working other than internal failure ? thanks simon

forums.mercedesclub.org.uk

https://forums.mercedesclub.org.uk/index.php?threads/om642-turbo-actuator.170922/[/URL

The best solution is to get it to an indy who can put it on Star and read the live values to see exactly what is happening

 

[Doug1234]

If the revs were higher then it means it had gone down a gear or two if it was still holding the same speed.
The fact you turned it off and on and it then ran ok and the fact it had no codes to be read when it did it previously says to me it’s the gearbox playing up and I do not know what type of gearbox you have but the symptoms are typical of a conductor plate on a 722.6 gearbox.
I expect the later gearboxes May do the same thing but I only have experience of a couple of 722.6 equipped cars I have owned doing random odd things like this when the conductor plate is going bad and 99% of the time a restart would stop symptoms

 

[tode]

Larkone
A good video - thanks .

In my part of France there are no Indies as such (just general garages) or MB. And the last time it happened, MB found no faults (the EML hadn't lit up and it didn't come on this time, either).

The car only has 75000 miles, so it wouldn't seem worthwhile to have the whole turbo changed as "preventive", no ?

 

[tode]

Doug, It's a 7G+ distronic box 722.903. The box was serviced a few months after the last occurrence.
I didn't think of trying to shift gear when it happened (brain occupied by other non-MB problems . . . ).

It won't be easy finding the solution if it only happens every two years. Wouldn't a box problem automatically throw up a fault ?

 

[Doug1234]

My experience with the earlier boxes says no as they do some really odd stuff until eventually a code pops up
Someone will come along who is familiar with the later boxes and comment on them , but as I mentioned I have no experience of the 7g box

 

[Wighty]

I think that the problem will occur more frequently and at that point a fault code will probably be triggered .
But as said , suspects will be , turbo actuator , swirl flaps/inlet port motor , exhaust back pressure sensor as regular suspects .

 

[Wighty]

What mileage are you on buddy ?

 

[malcolm E53 AMG]

I had this on my S210 it only happened once half way down the M5 pulled off to the services and when the car was restarted it cleared,
it never occurred again during my ownership and the car covered a lot of motorway miles as you say no codes to help reveal the cause and I didn’t pursue it.

 

[V6Matty]

Don’t rule out a boost leak after the turbo,

 

[tode]

What mileage are you on buddy ?

75000ish miles; So not completely worn out yet

Having seen the prices of new turbos, I'm not too keen on changing without proof . . .

 

[Wighty]

75000ish miles; So not completely worn out yet

Having seen the prices of new turbos, I'm not too keen on changing without proof . . .

Just the actuator which is the black box on top of the turbo , maybe £100-140 for a refurb ?
If you are handy you can take it off and clean it out yourself

OM642 Actuator clean out and refit .

Due to the sunshine , I had done this job 3-4 years ago so I thought I would remove the actuator again and clean it out . Turbo shield removed , 3 bolts . Then the split ring on the actuator arm popped off very carefully you could tie some cotton on it , but I only did this when I refitted it ...

forums.mercedesclub.org.uk

 

[tode]

Thanks Wighty. Yours looks to be a bit simpler to get to . . .
On mine, I presume I would have to dismantle all the air intake to the two banks in order to access the actuator itself, as in photo.
Am I looking in the right place ?

 

[Wighty]

Thanks Wighty. Yours looks to be a bit simpler to get to . . .
On mine, I presume I would have to dismantle all the air intake to the two banks in order to access the actuator itself, as in photo.
Am I looking in the right place ? View attachment 86183

The bolts are on the back of the actuator (3?) you might have to move that shield on top of the turbo .
There is an electrical connection under the actuator and a split ring on the back of the actuator arm that needs removing as well (don’t drop it ) .
Might be worth someone with the newer om642 than mine confirming it all though ….just in case

 

[Myros]

Yep to the last reply by Wighty. Ours did this not long ago at 81,000. You can get replacement actuators from ebay, at variable prices, depending on whether you want a refurbed Hella, or a brand new and cheaper Chinese version. the important thing is to get the number from your actuator, and match it to the numbers the replacements say they fit. there are several variants out there. there are also several vendors. Some want yours as return unit with a refundable charge in the price, others will sell you just a bare unit. You should be able to get one for around a £100 give or take at the lower end. You can leave the MAF unit in place, but do take off the turbo heat shield. Make sure you have a magnetic tool handy, and don't drop a socket down the back like I did. ( d'oh). the little circlip on the arm itself is well fiddly, and I had the magnet on it as i shimmied it off. The new unit will have its arm in a standby position, and you will easily be able to fit the link arm from the turbo to it. Check it is running freely before you do so, and apply some copper thread grease to any moving parts. Once you have it all remantled, don't start the engine striaght away, just turn the ignition on while watching the arm. It will do a little dance and then find home. start the car up, watch the arm move around while you gently rev the engine. It should take care of the trouble. Beware though, mine came about after I'd done the EGR and the exhaust gas pressure sensor, which had gone the way of all flesh just beforehand. These things do have a finite life. just not the same one for all of them.

 

[tode]

Thanks Wighty.
Myros, does the actuator need to be programmed in or anything, or is it plug n play as the younguns say ?

 

[Larkone]

Thanks Wighty.
Myros, does the actuator need to be programmed in or anything, or is it plug n play as the younguns say ?

Its plug and pray and play. I can change one in 15 mins, you just remove the heat shield and three bolts. A tip - put a piece of fishing line or similar through he circlip on the actuator arm before you take it off so you don't have to take the engine out to retrieve a dropped circlip.