Author Topic: M110 timing chain renewal  (Read 16726 times)

oscar

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Re: M110 timing chain renewal
« Reply #15 on: 24 March 2009, 05:54 PM »
Wow - great achievement and thanks for going to all the trouble to document it as I know how long it takes to do that part alone.

I see you used the "Double cable tie" method - it is quicker with three small vice grips but cheaper with a packet of cable ties.

I don't know anything about the earlier timing chain tensioner other than it bears little resemblance to the 6.9 one unlike the latter type.

The 6.9 one has a definite serated surface that engages in a small circlip to provide the ratcheting with no balls and cups.

Pleased the chain end resurfaced.

Bill

Thanks Bill, I was goint to do the vice grips method after seeing your thread but I only had one small enough and since the sprockets don't sit tall like the V8's I figured knowing my luck I'll knock one of the grips accidentally and it'll tumble down the front cover.

It's running well now, I've run it for about 15 mins giving it a boot full occasionally but I have to sort out the chain whirring noise.  I think it's just the tensioner is too tight but will investigate when it cools down again.
1973 350SE, my first & fave

koan

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Re: M110 timing chain renewal
« Reply #16 on: 25 March 2009, 02:39 AM »
It's running well now, I've run it for about 15 mins giving it a boot full occasionally but I have to sort out the chain whirring noise.  I think it's just the tensioner is too tight but will investigate when it cools down again.

When I put in a new timing chain I thought there was a whirring sound. That was with a new tensioner rail and following the proper procedure with the tensioner.

I was a bit worried about the noise but its gone now.

Maybe new chains and new rails need to bed in.

If you followed the book on the tensioner it should be OK.

koan
Boogity, Boogity, Boogity, Amen!

TJ 450

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Re: M110 timing chain renewal
« Reply #17 on: 25 March 2009, 03:43 AM »
That doesn't look like a ratcheting tensioner with those ball valves, but when you pulled it apart, did you notice corrugations on the bore?.

The only way you would have a tensioner that is too tight would be because it is a ratcheting type that was pushed in by force other than spring tension or oil pressure and it is not able to return to the natural position by design.
If the tensioner is non-ratcheting, it will automatically adjust itself and tension the chain accordingly.

If everything checks out OK otherwise, I would just play it by ear and see how it goes.  I haven't heard that sound after any of my chain renewals though. 8)

In any case, that's excellent work. I'm sure you'll notice a huge difference when you get out on the track. :)

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

oscar

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Re: M110 timing chain renewal
« Reply #18 on: 25 March 2009, 07:31 AM »
No there was no serations or corrugations I should say.  Smooth throughout.  The way I see it is that I’m sure it’s just oel pressure whereby oel gets trapped in there by two opposing ball valves at either end.  That faulty ball valve pictured on the other page where the ball was out of its cage means pressure wasn't maintained when not running.  But this wouldn’t affect nor is accountable for causing the whirring IMO.   The spring and valves plus oel pressure only counter act chain stretch and the pressure pin only moves by about one cm.  It will always push out as soon as the engine’s started whether the back pressure valve works or not but the movement in the rail for when the pressure pin is extended and collapsed is minimal.  It’s why I believe if I back off the locking ring it should be ok.

So that's what I did.  Eased it out a bit, went till I thought I was happy with it but the plug wouldn't fit now.  So I had to screw it back nearly to where it was before.  The result was the engine was still hard to turn but a tad easier.


Maybe new chains and new rails need to bed in.

Yeah I'm thinking that too.  Went for a test run and it behaved.  Something I noticed about the new chain was that the actual links looked a fraction thicker.  It shlould slowly disappear

Speaking of test runs.  No noticeable difference in performance. :-\  The red mark for each gear seemed higher but there was no acceleration improvements.  0-100km/hr actually seemed to take a little longer and the 10second barrier remained elusive.

Here's the vid.  It's not much and my phone memory ran out at the end but if nothing else, the sounds are really good.

http://www.youtube.com/watch?v=yaex8zoHZDs
1973 350SE, my first & fave

oscar

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Re: M110 timing chain renewal
« Reply #19 on: 04 April 2009, 02:40 AM »
Well the whirrring has gone.  8)  After half the day spent on working it out, simply put, if you redo a timing chain you need to reset the tensioner (properly).  

I get a bit lost when reading the manuals, although now I've read the procedure again it makes sense more and more.  Either the translation can be a bit vague or some things they should highlight or emphasise aren't.  But anyway, resetting the tensioner is a must.  I thought it involved simply removing it whilst the new chain goes on then reinserting and retourquing it but let me emphasise to any m110 owner that after a timing chain renewal the tensioner needs to be pulled apart and reassembled and reset.  It just didn't sink in the first time I read it and my confusion wasn't compounded by the fact I didn't really know how the tensioner worked.

It looks a bit daunting in the manual but it's not.  The most improtant thing is to not loose anything and when reassembling the tensioner, the pressure pin does not stick out past the housing at all.  If that was in the manual text I wouldn't have been asking about a whirring timing chain I reckon.  To make it easier, here's a few more pics, some of which should be in the manual to make life easier for the first timer or DIYer.  Please note this is an early version tensioner and is slightly different to the later style which I would assume is on all later 70s - 80s M110s. The later style has fewer parts (8 v's 12) but looks identical on the outside according to pics in the manual. 

There is a teardown pic in the manual, the only differences are mine's colour and the ball cage and valve disc are in situ still either end of the main spring (7).  Also the snap ring for the Pressure Pin is still connected at (4)



I wont go through the whole procedure but I realised that after reassembly, the tensioner should look like the following two photos.  The ball locating ring (9) should be screwed in lightly (two turns as per manual) and the pressure pin should not protrude past the tensioner housing (2) (2nd pic). 




Unbekown to me earlier is that the inside of the housing has corrugations shaped in a way to catch the pressure pin snap ring (4) so it doesn't move too far foward but more improtantly, it wont move backwards at all.  When there is slack through wear the oil pressure can push the snap ring into a new corrugation.  It's like a new set point.  Does this mean it's a racheting type??


When installing back into the motor, tensioner must remain in the state pictured above.  Any over tightening or bumps could cause the pin to jump forward and the tensioner will need another teardown/rebuild/reset.  
So, the tensioner is slid into place.  The locking ring (not pictured) is torqued to 50Nm, the ball locating ring (9) to 25Nm approx to which basically you'll hear the tensioner jump forward beforehand and will have to tighten the ball locating ring a bit further.  Then the plug goes in at 50Nm (not pictured).

So that's it, car's running normal again without the whirr!

http://www.youtube.com/watch?v=cjRjc09KOZA
1973 350SE, my first & fave

TJ 450

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Re: M110 timing chain renewal
« Reply #20 on: 04 April 2009, 10:37 AM »
It's good that you discovered that, Oscar. That means it is in fact a ratcheting tensioner, but slightly more complex than the M-100 version. That snap ring and the corrugations inside the bore a what forms the ratcheting mechanism, ie once it tensions, it won't go back. 8)
The 6.9 tensioner must be reset in exactly the same way and it then extends under spring pressure to the required position.

Driving with an over-tensioned chain wouldn't be good for obvious reasons, so that's good that it's sorted.

Tim
« Last Edit: 04 April 2009, 10:40 AM by TJ 450 »
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

oscar

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Re: M110 timing chain renewal
« Reply #21 on: 04 April 2009, 03:28 PM »
Excellent.  I was hoping that would be the case.  If anyone says it's definitely not racheting, I'm referring them to your post TJ ;D

I wish I had a later version on hand to compare.  It dispenses with ball valves but does the same thing and needs resetting in the same way.  It could be more similar to the 6.9 one.
1973 350SE, my first & fave

koan

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Re: M110 timing chain renewal
« Reply #22 on: 04 April 2009, 03:49 PM »
I wish I had a later version on hand to compare.  It dispenses with ball valves but does the same thing and needs resetting in the same way.  It could be more similar to the 6.9 one.

Good you found it oscar, could have been needing a new-new chain and rail very soon.

6.9 is very similar, the pressure relief valve is built into the end of the pressure rod and can't be removed.

Can you add a job number to your picture post so others can find the the relevant pdf in the library?

koan
Boogity, Boogity, Boogity, Amen!

oscar

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Re: M110 timing chain renewal
« Reply #23 on: 04 April 2009, 04:32 PM »
Good idea.  Although there a number of job numbers involved because throughout the text there's a few references to "see job 05-xxx". For example there's the need to move the york air conditioner compressor (not sure about the later rotary compressors).  My compressor was a PITA to remove but I'd already removed it permanently from Povo months ago.  Plus there might be the need to replace different rails and a few job numbers relating to dealing with the camshafts, rockers etc.  I found it easier to flick through my own manual but for starters the two main job numbers are below and people should then refer to the various job numbers listed within those two pdfs:

Link Chain tensioner
Link Timing chain

1973 350SE, my first & fave