2006 E320CDI not used for months, when started serpentine belt smoked and snapped, alternator appears to be seized

[Stocho]

Hi, the picture of the W211 alternator I found last night did have a proper nut - so just a standard socket would do. But upon doing some more research today it looks like it might be a splined female socket.

Also it appears that even if the alternator is stuck the wheel should still rotate freely anticlockwise due to some additional one-way bearing/clutch in the pulley. Does it mean that in addition to the seized alternator I have a seized pulley as well (or perhaps there is no one-way clutch on this model)?

There is a detailed video for another alternator

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To remove a pulley they use 33 spline socket with a hole through which they insert 8mm hex. So I suppose to connect to the shaft in their set up I would use 8mm hex (and hope that it can take the extreme torque required). What are the corresponding tools for E320CDI 2006?

 

[Smiley]

If there is a clutch fitted then it may be just that that has seized. The fact that the pulley itself has seized does not mean that it will be more difficult to remove from the alternator. There is a special tool available to remove the clutch ( iirc). If it were me I would remove the clutch with the alternator in the car - then you can check if the alternator turns freely without the clutch fitted. If not then I would suggest removing the alternator and stripping it - just putting a breaker bar on it won't fix it properly in my experience.

btw re starting a car with a ctek connected - unlikely to damage the car but could well damage the ctek

 

[Stocho]

If there is a clutch fitted then it may be just that that has seized. The fact that the pulley itself has seized does not mean that it will be more difficult to remove from the alternator. There is a special tool available to remove the clutch ( iirc). If it were me I would remove the clutch with the alternator in the car - then you can check if the alternator turns freely without the clutch fitted. If not then I would suggest removing the alternator and stripping it - just putting a breaker bar on it won't fix it properly in my experience.

btw re starting a car with a ctek connected - unlikely to damage the car but could well damage the ctek

Today I sprayed WD40 in the holes in the alternator casing. I tried to unseize it by grabbing the pulley with plumbing grabbers (with a piece of the belt to protect the pulley from damage) but it did not work. So I ordered a toolkit that I hope will enable me to both unseize the shaft and remove the pulley (Alternator Freewheel Pulley Removal Set 18pc 5060451293548 | eBay)

Removing the alternator is quite a big job and likely to require removal of the radiator fan, disconnecting of radiator hoses that are in a way and, possibly removing the radiator as well. Also access from under the car could well be required and I do not have that. So I really hope to fix it without removing it....


Even putting the drive belt on this car is not as easy as in the numerous videos that seem to be either for pre-facelift car or for smaller engines. In this car the tensioner pulley is right behind a huge thick pipe - turbo air pipe. So that will require removal (as I think it is actually mathematically impossible to put the belt in without at least partially removing that pipe). That is held by Torx-like nuts - but hopefully some normal socket will take them. Also as I found out the tensioner nut is not 17mm as on all the numerous videos but some sort of torx/star - but I think I found a standard socket that will work with it.

So I hope to receive the toolkit my the middle of next week and then will try to proceed.

 

[24 VRT]

Today I sprayed WD40 in the holes in the alternator casing. I tried to unseize it by grabbing the pulley with plumbing grabbers (with a piece of the belt to protect the pulley from damage) but it did not work. So I ordered a toolkit that I hope will enable me to both unseize the shaft and remove the pulley (Alternator Freewheel Pulley Removal Set 18pc 5060451293548 | eBay)

Removing the alternator is quite a big job and likely to require removal of the radiator fan, disconnecting of radiator hoses that are in a way and, possibly removing the radiator as well. Also access from under the car could well be required and I do not have that. So I really hope to fix it without removing it....


Even putting the drive belt on this car is not as easy as in the numerous videos that seem to be either for pre-facelift car or for smaller engines. In this car the tensioner pulley is right behind a huge thick pipe - turbo air pipe. So that will require removal (as I think it is actually mathematically impossible to put the belt in without at least partially removing that pipe). That is held by Torx-like nuts - but hopefully some normal socket will take them. Also as I found out the tensioner nut is not 17mm as on all the numerous videos but some sort of torx/star - but I think I found a standard socket that will work with it.

So I hope to receive the toolkit my the middle of next week and then will try to proceed.

My E320cdi went in to my indie for a D service yesterday and he noted noise from the alternator pulley. Advised that this failure does crop up on higher mileage OM642 engines (642-920s) and when they go it does everything you experienced. Lucky for you it wasn't when the engine was running at speed as if the belt gives way at high speed it can fly off/about and create lots of other damage. The good news is you should find the alternator itself will be fine - just this pulley mechanism that has seized.
Yes you need the special tool to remove it - I'd also strongly recommend not ordering the replacement pulley until you have got the details off the failed one, as there are apparently several variations fitted. INA is the OEM and the following is probably what you need:-
MERCEDES E320 S211 3.0D Overrunning Alternator Pulley 05 to 09 Clutch INA New 4005108326935 | eBay
The indie outlined the method needed to do the replacement, but on the basis my days of wielding spanners are long gone, mine will be going back to him to do for me. Hope yours goes OK.
P.S. I found a simple explanation of what this pulley does on 'tinternet - think of it as the freewheel gear on a bicycle. You can pedal in one direction and it results in the wheel being turned, but if you pedal in the other direction there is no effect (drive or retarding) on the wheel.

 

[geoffus]

Surely if the alternator will not turn without the belt fitted, then the alternator has seized ?
Even if the pulley has seized the alternator would freely spin just as if the pulley was solid and didn't have a bearing/clutch, looks to me as if the alternator needs removing.
Unless i'm missing something.

 

[E55BOF]

If the alternator shaft will not turn at all by hand, in either direction, then whether or not it has an overrunning clutch pulley or not, the alternator is seized.

Be careful using standard sockets or drive bits on Star E Torx bolts, whether male or female heads; you need a set of the correct sockets and drive bits. An ordinary socket or drive bit but may just round the splines off and make things worse.

 

[Spider10]

I had this yesterday not on a MB you may aswell take the alternator off and replace it waste of time trying to force it strip it down etc

 

[Spider10]

I had this yesterday not on a MB you may aswell take the alternator off and replace it waste of time trying to force it strip it down etc

Im also sure its a left hand thread on the alternator pully

 

[Petrol Pete]

If you can't get it to turn when its bolted to the engine it will be a real pain to get it to turn on the bench. This is a new one on me, but can you get to the back of it to remove the regulator and brush assembly ? If so I would do that and get some heat on it, staring with a hot air gun. Good luck.

 

[Stocho]

Hi,

Not good news unfortunately...

Received the toolset today ( Alternator Freewheel Pulley Removal Set 18pc 5060451293548 | eBay ).

Using the 33teeth socket with 0.5m breaker bar I was quite easily able to remove the clutch pulley. For the shaft unfortunately it is just a T50 bit - one of the smaller shaft bits in the set. It snapped when I tried it with the 0.5m breaker bar. Literally the bit broke with a piece of it still left in the shaft.

I then put the pulley back on and used the 33teeth socket to kind of tighten - ides was that once the pulley was firmly tightened I would be effectively able to transmit that torque to the shaft. I was applying quite an extreme force to the breaker and it was yielding a bit but was probably more tightening that pulley on the shaft rather than unseizing the alternator... so at this point I gave up trying to unseize it.

The idea to unseize was not to save 100 pounds (the cost of second hand alternator with a 3month warranty) but to save extreme trouble of removing it. I do not have access from the bottom of the car so have to work from the top. Looks like there was a DIY with pictures on another forum but the pictures are gone. Sounds like to remove the alternator I would have to remove the radiator fan, radiator hoses and also some extremely thick airpipe and even then it would be very tight....

W211 E320 CDI Alternator DIY - MBWorld.org Forums

Diesel Forum - W211 E320 CDI Alternator DIY - OK I thought I would do a DIY here specific to E320 CDI as some parts are different from other models. This shows both complete replacement and just replacement of voltage regulator, which in my case solved the issue. I kept getting Battery low...

mbworld.org

There is one thing that I completely do not understand. I have seen several instructions saying that the battery must be disconnected and even the back up battery must be disconnected when removing the alternator. Some instructions even go further and state that you must tape off the battery terminals to prevent accidental reconnection. Why would that be the case? Is is because of fear that an alternator might act as a motor and suddenly start rotavating (I would imagine possible theoretically but probably not in practice) or is there some other reason for that?

 

[Spider10]

Its to stop an accidental arc from the alternator connectors quite easily done

 

[Stocho]

Its to stop an accidental arc from the alternator connectors quite easily done

I see... and even the back up battery is a risk in this respect as I would imagine it would power only very high priority circuits and could not leak current to the alternator?

Also I thought even when changing the battery you are supposed to keep power to the car (for example by connecting another battery, a third one somewhere in the circuit). Won't total loss of power to the car cause problems (car radio codes, ECU etc)?

 

[Spider10]

Tbh im not sure about the back up battery but if you connect another battery to the car i dont see the point in disconnection it doesn't make sense

 

[Stocho]

Tbh im not sure about the back up battery but if you connect another battery to the car i dont see the point in disconnection it doesn't make sense

What I meant is that the usual dogma I heard is to never leave a car without a power as that can cause expensive to fix issues. So when someone just wants to change a battery (and no other work) I heard that the safest way to do it is to have a third battery fully connected to the circuits of the car during the process so that the car is never without a power. So if I disconnect both batteries will I run into other problems that will then require recoding the ECU, some other recoding, etc?

 

[jc651]

When ever I do a alternator job I leave the battery connected so you don't loose any coding. Once the live ( thick cable) is removed off the back of the alternator wrap the end in a cloth and then stick a rubber glove over the end and cable tie it out the way. Sounds dodgy but as long as your careful it saves time messing around setting up the radio code and other stuff on the car.

 

[Spider10]

I recently changed my jag battery and jag state to connect a different power supply as you sat which I did but having to struggle trying to get the battery out i knocked off the clip so no power to the car at all connected new battery no coding needed or any issues
I agree you could tape it up but just be aware if the spanner or socket you are using touchers anything metal it will arc

 

[pmcgsmurf]

The Aux battery on a W211 goes through a Relay so is not connected to the Alternator without this being energised.

I would never remove an Alternator without disconnecting the battery.
Just remove the negative terminal in the boot and you are good to go.

You will need to re-sync the windows etc. but very straight forward.

 

[Stocho]

The Aux battery on a W211 goes through a Relay so is not connected to the Alternator without this being energised.

I would never remove an Alternator without disconnecting the battery.
Just remove the negative terminal in the boot and you are good to go.

You will need to re-sync the windows etc. but very straight forward.

Makes perfect sense. Would not want the risk of cremating my fingers so definitely would fully disconnect the main battery. And so, I do not need to disconnect Aux battery?

Also does it by any chance mean that in order to charge Aux battery using a charger (I had CTEK connected to to my car for several days by now) the car key has to be in? What I noticed is that the car would take about 5 seconds to respond to the radio key lately (despite being on CTEK charger for days). And today while I was trying to unseize the alternator the key was in (though not ignition) and the charger was also connected and now it responds instantly to the key... So I am now thinking of leaving the car with a key in position I (or perhaps even II) for several hours while it is being charged by CTEK so that the charge could flow into the Aux battery....

 

[pmcgsmurf]

I wouldn't worry about the Aux battery.
The Relay is controlled by the BCM and is only energised if Engine Running & system Voltage Low.

 

[Stocho]

Is it feasible to change the alternator on this car (2006 facelift E320CDI) with no access at all from below the car (i.e. I would be working only from the top of the engine)?

If possible to do with access from the top only:
So, I take I will have to disconnect the radiator hose (and flood the bottom tray with coolant) and the coolant hose that travels towards the front of the car. I will have to remove the radiator fan . Will I have to remove water pump as well? Will I have to disconnect the huge air hose (probably turbo intercooler)? Is there anything else I will have to remove to allow access?