Hey guys, my front crank shaft seal has just started leaking profusely and I'm considering a diy on this. Does anybody have any special tips. Is the bolt standard or reverse thread? Looks pretty straightforward but on a Mercedes you never know what hidden procedures lie in wait!
2008 S550 Crankshaft Seal Replacement
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2015 S550, 2010 E350 P1/P2, 2002 ML320
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Just curious, how did you discover the front seal is the source of your leak? I was solidly convinced mine was leaking (actually bought the bolt and seal!) until I did the dutiful deed and pressure washed my engine, also 2008 S550. What I found is that the oil was not leaking from the front seal but from the chain tensioner bolt which is hidden by the alternator! I was able to confirm using an inspection camera while the engine was running.
When I removed the alternator and put a torque wrench on the tensioner bolt I got at least 1/4 turn before it started to snug up, then continued to 70Nm and cleaned everything thoroughly. No leaks for 6 months now.
The front crank bolt is typical right hand thread.
If you do proceed with replacing the seal you'll need a flywheel lock. Removing the bolt is not difficult, but torquing the new bolt requires 200Nm + 90deg for tightening, there is a flywheel lock to make this easier (see attachments below.)
Thank you so much for the prompt reply! Well On mine I can see a steady drip coming from behind the harmonic balancer. Do you purchase those lock tools or did you rent them from somewhere? I'm hoping to remove the bolt and reinstall with an impact driver. I do realize that would require removing the radiator. As far as torque I have heard the 200 N. but I didn't realize it was another half turn beyond that.. holy cow! I was going to do the old trick where you put a bit of white nail Polish as reference marks and get it torqued back to that point?
2015 S550, 2010 E350 P1/P2, 2002 ML320
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2,669 Posts
I bought this one, I have several Mercedes (always buy used!!!) and special tools pay off for me.
I would definitely NOT reinstall the bolt with an impact driver, you'll be putting a lot of percussive force through the bearings, chain, guides, etc., removal maybe ok, but I'd never install a crank bolt with one.
For the torque angle, I use an old school dial gauge like this one, maybe someday I'll break down and buy a digital torque wrench with the angle gauge built in!
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I would definitely NOT reinstall the bolt with an impact driver, you'll be putting a lot of percussive force through the bearings, chain, guides, etc., removal maybe ok, but I'd never install a crank bolt with one.
For the torque angle, I use an old school dial gauge like this one, maybe someday I'll break down and buy a digital torque wrench with the angle gauge built in!
ZKTOOL 1/2" magnetic Torque Angle Meter, A New Type Of Drive torque angle gauge, Including 360°Adjustable 1/2" Drive Torque Meter, 16-Inch Magnetic Soft Rod, And Powerful Clamping Arm. - - Amazon.com
ZKTOOL 1/2" magnetic Torque Angle Meter, A New Type Of Drive torque angle gauge, Including 360°Adjustable 1/2" Drive Torque Meter, 16-Inch Magnetic Soft Rod, And Powerful Clamping Arm. - - Amazon.com
www.amazon.com
Holy cow so it's 200 N meters plus an additional 90ﾟ? Man that sounds like way overkill. Also was curious why it's necessary to block the flywheel AND the harmonic balancer itself that seems like overkill as well? I did sign up for a one month subscription for WIS and it only says the 200 N meters it doesn't mention the additional 90 ....strange.
Sorry I saw that the 2nd time I looked I overlooked it. Was curious is it absolutely necessary to put the engine at TDC when removing the bolt? Also did the balancer come off easily or did you need a puller and if so what type did you use? And finally is it really necessary to have the front locking tool as well I would think just the rear flywheel would be adequate.
2015 S550, 2010 E350 P1/P2, 2002 ML320
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Sorry if I mislead you, I did not replace my seal because I found it was the Chain Tensioner bolt that was leaking. 
As for TDC, it is not clear to my why that is important here, the harmonic balancer is keyed and can only go on one way so your guess is as good as mine. I have the holding tool for the balancer from a previous main seat replacement so intended to use it before I found the source of my leak. What I've found about WIS procedures is that if you go through a few of them with hands-on practice they start to make more sense. Stuff that seems like overkill become time savers.
As for TDC, it is not clear to my why that is important here, the harmonic balancer is keyed and can only go on one way so your guess is as good as mine. I have the holding tool for the balancer from a previous main seat replacement so intended to use it before I found the source of my leak. What I've found about WIS procedures is that if you go through a few of them with hands-on practice they start to make more sense. Stuff that seems like overkill become time savers.
I completely understand. I've got an old vintage Ferrari that I work on so there are definitely a lot of different ways to skin a cat especially when working on that car. Just curious if you have a part number for the balancer holding tool... wis actually shows 2 different ones.
272589000700
272589010700
Ridiculous!
272589000700
272589010700
Ridiculous!
2015 S550, 2010 E350 P1/P2, 2002 ML320
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2,669 Posts
So, looking more closely at the WIS instructions, the holder is only needed for the 221.095/221.195 chassis which is the S400 Hybrid. The two variants are for the two pulley types available on the Hybrid. All the other W221s with the M273 would use the flywheel lock.
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2015 S550, 2010 E350 P1/P2, 2002 ML320
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LOL good point!
Thank you for deciphering that....that is brilliant.
I just ordered the seal and the flywheel lock you recommended on ebay. It looks like a pretty straightforward job hopefully the balancer will come off easily. BTW I called the dealer and they quoted me $1250 for the job! I did want to ask I'm intrigued about the leak you had behind the alternator... did you have to remove the alternator to tighten that bolt or is it accessible without. I Absolutely positively have the seal leak but it is also a little wet back behind and on the side where the alternator is but very slightly I think the fan is blowing oul back in there.
I just ordered the seal and the flywheel lock you recommended on ebay. It looks like a pretty straightforward job hopefully the balancer will come off easily. BTW I called the dealer and they quoted me $1250 for the job! I did want to ask I'm intrigued about the leak you had behind the alternator... did you have to remove the alternator to tighten that bolt or is it accessible without. I Absolutely positively have the seal leak but it is also a little wet back behind and on the side where the alternator is but very slightly I think the fan is blowing oul back in there.
2015 S550, 2010 E350 P1/P2, 2002 ML320
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2,669 Posts
I don't see a way around removing the alternator in order to get at the chain tensioner bolt head. In this photo you can see the upper/lower alternator bolt holes and the chain tensioner right in the middle. If you do decide to remove the alternator, best to get the $6 dipstick tube seal and replace that while you have easy access to it.
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I thought I would report back after replacing this seal. The job went really really well. A few notes if anybody is going to tackle it... I only removed the electric fan to give me a little more working room. I used a 2' breaker bar with a 27 mm socket and a long 2' long pipe over that to crack that bolt loose and it was in fact standard thread. I Did purchase the flywheelholder....it is a must. As far as the seal the old man came out very very easily with a Flathead screwdriver. The Mercedes brand seal is a very interesting seal it is a Teflon coated seal with no Spring and it has to be put in dry I did not know this and I ruined the seal it leaked immediately! Rather than dropping another $36 bucks on the Mercedes seal and the fact that my local dealer was out of stock, I opted for an aftermarket seal of a traditional design with double lip and a spring and I'm sure it will last the life of the car. As far as torching the bolt back down Mercedes does recommend 200 N meters which is 147' pounds plus an extra 90ﾟ! I don't have a torque ranch that goes that high so I just took white nail Polish and made a mark on the bolt and the hub and I tightened it backup to exactly where it was before which is unbelievably tight. I had to use the breaker bar and pipe as well. Put it all back together and it is working perfectly absolutely 0 oil leak ....it's so nice to have a dry oil leak free car again. I can go over friends houses and park in their driveway!
Good job! Did you take any pictures? A seal without a spring will cause very little friction so the tolerances must be tighter. It will still cause friction though. Your balancer was worn and your seal was new so that was probably the source of your leak unless you actually did damage it during install. If you had put a new balancer on it as well, it probably wouldn't have leaked. That being said, a seal with a spring will provide constant tension so the friction will be greater. The new seal probably won't last as long as your original one did. It is a 15 year old car though.
Actually the balancer was absolutely flawless no groove or wear. The seal that Mercedes uses is a springless low friction PTFE coated seal. I've never seen anything like it. I found out later it has to be installed dry.... absolutely free of oil and grease or it will not seal. On the initial start up which occurs seconds after the start up apparently the PTFE rubs off and adheres to the shaft....or something like that. Mine leaked within minutes and my heart sank but II didn't fully torque the pulley or reassemble anything for the test to start up so it was easy to redo it. I opted for a traditional spring lip seal. Hopefully it will last the remaining life of the car! Unfortunately I didn't take any pics....wish I would have. The part number of the aftermarket seal is 710289. It has the exact specs/size.
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