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

[Stocho]

Hi,

E320CDI 2006 (not mine, mine is 2007) has not been used for about 2months and before that for another 2-3months due to family members who normally use it shielding. Today I tried to start it. It would not start due to what I believed to be a battery problem. So I used really thick jump leads to connect a spare battery, and then it reluctantly started after much struggle (well the spare battery is also quite old and has not be charged recently).

Almost immediately lots of smoke came out from the engine compartment and it would not stop smoking until serpentine belt snapped. After inspecting all the wheels/pulleys I could rotate all of them by hand other than the main engine (which I would not expect to be bale to rotate) and the alternator wheels/pulleys. There is like a layer of burnt tar / plastic on the pulleys with by far the most on the alternator pulley.

Also I noticed that even before the engine is started, inserting and rotating the ignition key was much stiffer than is usual ... I think even that function is electrically assisted and appears not to be working now.

Does it mean that the root cause is that the alternator is seized? Could it be caused by the fact that the battery was flat (due to car being not in use for so long) and hence some steps not performed in the starting sequence (given all the noise that normally occurs when key is moved to position 1 even before the engine is started some things are clearly being done even before the car is started))? Is there a reasonable chance that the issue could be fixed just by charging the battery and changing the serpentine belt? Does it mean that the oil was not being pumped when the engine was run (in Parked gear), including revved, for about two minutes and could it have damaged the engine?

 

[andrewc1267]

You need to be really careful not to connect jump cables with the key in the EIS lots of horror stories of lost coding and expensive repair

 

[E55BOF]

Yes, the car does 'wake up' as soon as it detects a key, but if the battery was really low on charge, there might not be enough voltage to trigger the process.

The alternator has seized.

The engine lubrication would not be affected by what you did.

Were there any dash warning lights or error messages while the engine was running? If not, a new alternator and (probably) a new battery should sort it out.

 

[geoffus]

Are you saying the alternator did not rotate?
But all the other pulleys were ok ?
If so you will have to remove the alternator and replace this or at least free off the bearings for a temp fix.
I cant see any damage you could have done by jumping the battery, thats what the jump start points are for.

 

[Stocho]

Yes, the car does 'wake up' as soon as it detects a key, but if the battery was really low on charge, there might not be enough voltage to trigger the process.

The alternator has seized.

The engine lubrication would not be affected by what you did.

Were there any dash warning lights or error messages while the engine was running? If not, a new alternator and (probably) a new battery should sort it out.

No error messages other than a red "Battery / Alternator" screen towards the end of about two minutes that the engine was run for.

So it looks like Engine Oil pump is not driven by the belt? So I suppose once the battery is fully charged I could start the engine again and run it for several minutes with no belt and see whether there are other problems / error messages?

Is there something I could try to unseize the alternator (I am thinking of some sort of grabber like oil filter wrench)? ( Strap Wrench Set ) My thinking here is that perhaps it seized purely through total non-sage for two months and might be ok if somehow I manage to unseize it?

 

[Stocho]

Are you saying the alternator did not rotate?

Yes the only pulleys I could not rotate are the main engine pulley (which I would not expect to be able to rotate using my bear hands) and the alternator pulley. All other pulleys are very easy to rotate by hand.

 

[Stocho]

You need to be really careful not to connect jump cables with the key in the EIS lots of horror stories of lost coding and expensive repair

Might have done that.... Also sometimes I start a car with charger (CTEK) connected to it. Is it also dangerous?

 

[geoffus]

Might have done that.... Also sometimes I start a car with charger (CTEK) connected to it. Is it also dangerous?

You won't cause any damage by jump starting, if there is any damage it was there already.

 

[geoffus]

Yes the only pulleys I could not rotate are the main engine pulley (which I would not expect to be able to rotate using my bear hands) and the alternator pulley. All other pulleys are very easy to rotate by hand.

Is it definitely the alternator seized ? Normally the bearings just wear and rumble away.

 

[MrGreedy]

I had this, twice, in relatively short succession on another car. Occasional summer use. Went to start it one spring, symptoms as described, but stopped cranking quickly and checked by whipping the serpentine belt off and identifying the alternator. Changed it and all fixed (6 hours DIY on the car I'm talking about as I needed to strip the intake manifold to access the back of the engine).

Next spring after a winter slumber. Exactly the same thing!!!
Another alternator, another £150 and 6 hours!

Been fine for 8 years since.

 

[E55BOF]

If you run the engine with no serpentine belt, the coolant pump will not be driven, so no, you cannot run it with no serpentine belt fitted.

 

[Doodle]

From experience, I can tell you a 211 is nearly impossible to drive without a serpentine belt powering the steering pump.

My old one had an unexpected water pump failure and shipped the belt off, it took every ounce of my not inconsiderable bulk and muscle to get the slightest movement from the steering wheel.

 

[E55BOF]

It's a little easier once the car is rolling (gently) down a slope, but definitely a three Weetabix job...

 

[Smiley]

I have had an alternator do this (not on a MB) - a spare car that had not been used much anyway was left unused for 2-3 months over winter time. The alternator had completely seized and shredded the belt when started. I expected the bearings to be the problem but in fact the casing had oxidised inside and jammed against the windings. I stripped it all apart, cleaned it up and replaced the bearings even though there did not appear to be much wrong with them. If it is anything like the one I had (and symptoms are same) then the alternator definitely needs to come off the car and either be replaced or stripped down.

 

[Stocho]

Is it definitely the alternator seized ? Normally the bearings just wear and rumble away.

Definitely alternator pulley is seized. I cut a piece of the broken belt, placed it on that pulley, and used plumbing grippers and it would not bulge. But I seem to have removed the cover from the pulley, hopefully revealing a nut I can grab with a spanner....

 

[Stocho]

If you run the engine with no serpentine belt, the coolant pump will not be driven, so no, you cannot run it with no serpentine belt fitted.

I did not mean to drive for any distance, more like run it for a couple of minutes just to test whether there are some other serious problems...

 

[Stocho]

I have had an alternator do this (not on a MB) - a spare car that had not been used much anyway was left unused for 2-3 months over winter time. The alternator had completely seized and shredded the belt when started. I expected the bearings to be the problem but in fact the casing had oxidised inside and jammed against the windings. I stripped it all apart, cleaned it up and replaced the bearings even though there did not appear to be much wrong with them. If it is anything like the one I had (and symptoms are same) then the alternator definitely needs to come off the car and either be replaced or stripped down.

This video I found also mentions that it is not always the bearings that get stuck.

The video suggests spraying it with oil ... though probably it is not a good idea on W211 as it probably has too much electronics even in the alternator ....

But I am now thinking of trying a breaker bar ... just as in this video..

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Could I cause some more massive damage by doing this or is it safe to try with a 75cm breaker bar?

 

[Stocho]

Also does anyone know what size is that nut in the pulley? Should I try to force it only clockwise to make sure that I do not unscrew/loosen that nut?

Picture below is from the internet (but hopefully of exactly the same model)

 

[E55BOF]

This video I found also mentions that it is not always the bearings that get stuck.

The video suggests spraying it with oil ... though probably it is not a good idea on W211 as it probably has too much electronics even in the alternator ....

But I am now thinking of trying a breaker bar ... just as in this video..

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Could I cause some more massive damage by doing this or is it safe to try with a 75cm breaker bar?

The only thing you could damage by spraying WD40 or oil in there and applying force is the alternator, and that's not working anyway, so give it a go.

 

[MrGreedy]

Just don't go so crazy with the bar that you snap the bolts off in the engine block