Timing Chain Failure

[Ricardo]

I'm interested to know how these things work as well. I'm going to do the chain on my 300tdt (as Joe advised)) and found that the tensioner is quite expensive ($254 cdn.), but my parts guy tells me that there are "parts" available for the tensioner, including the internal spring. No mention of seals though, aside from the outer gasket. Has anyone taken these apart and studied them?
Thanks
Ricardo

[ja17]

Hello Ricardo and Malc,
The 300td chain tensioner is different from the W113 chain tensioners. The 300 td tensioner is fed oil under pressure from the oil pump. The w113 engines generate their own oil pressure.
See the new thread "Chain Tensioner Tour"

Joe Alexander
Blacklick, Ohio

[ja17]

Hello,
You can easily identify an older timing chain in your engine. This is the first thing to be suspect. Early chains had the "figure eight" style end plates, later had "oval" style.


Download Attachment: chain link plates.JPG
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Just because you have an early "figure eight" style timing chain doesn't, automatically mean it is bad. It may have low miles or be a recently installed "new old stock" item.

Joe Alexander
Blacklick, Ohio

[Naj ✝︎]

Phew  :|
Valve cover is finally off.
Found a bit that looks like a spacer/thrust washer - got between chain and left hand idler. Double chain sheared in half. Couple of teeth broken off idler.
Any thoughts on what the 'bit' might be?
Further stripping continues.



Download Attachment: TmgChn03.JPG
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naj

65 230SL
68 280SL

[ja17]

Hello Naj,

I cannot tell what the foreign part is from the picture. However I can observe that you have an early design "figure eight" style timing chain.

Keep us up to date. Ask questions, we can help!

Joe Alexander
Blacklick, Ohio

[Ben]

Could it be a piece if a guide rail ?

I know the replacement guide rails are plastic, the originals probably are too, so just a thought !

Aren't they plastic over aluminium and could this original chain have worn all the plastic off and picked up a piece of the aluminium ? It certainly looks like it has a groove in it, before it was bent, and it would havce had to be carried by the chain before becoming the "meat" in the sandwich !



Regards,
Ben in Ireland.
'64 230SL 4sp.

[Naj ✝︎]

Hi, Joe,
 

quote:Keep us up to date. Ask questions, we can help!

Question is how to set the inj pump sprocket to get correct timing when installing new chain.
We'll go with your idea of replacing the crank sprocket by removing the oil pan (with hood and rad off)

Thanks

Hi, Ben,

Early guide rails are aluminum with a lining, but this 'bit' is hardened steel.
Maybe more pieces in the pan will give a clue.

Will keep you posted of the findings,

naj

65 230SL
68 280SL

[Ben]

Mmmmm interesting !

I think you will have to remove the injector pipes and withdraw the pump to see the index marks !

I dont know of another way to view it !

Maybe the experts know a trick !

Regards,
Ben in Ireland.
'64 230SL 4sp.

[ja17]

Hello
Naj,  sorry to say the pump will need to be detached to re-align the timing marks.

Inspect all the timing gears and chain rails carefully. Plan on changing the crankshaft sprocket it is the most critical.

Joe Alexander
Blacklick, Ohio

[Cees Klumper]

Long shot on the FI pump: if you take off the injector lines AND the valves that they hook up to, would you be able to see or probe the plungers inside the pump and be able to tell that way how it is timed? This would avoid having to take the pump off - not that that is a really big deal.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[Ben]

quote:Long shot on the FI pump: if you take off the injector lines AND the valves that they hook up to, would you be able to see or probe the plungers inside the pump and be able to tell that way how it is timed? This would avoid having to take the pump off - not that that is a really big deal.

......you may be able to and a dial gauge would help but removing the pump isn't too hard and at least its definite !

Regards,
Ben in Ireland.
'64 230SL 4sp.

[ja17]

Ok Guys,
There is a method, it may be a little technical for the amateur. There are no specs in any BBB or any other manuals, but I can come up with the setting. Cees is on the right track about the process.

The method is used for Mercedes Diesel engines and Mercedes 300 SL fuel injection. It is a "drip timing" process and involves using a fuel reservoir tank and a drip tube.  You must remember that piston #6 on the injection pump serves cylinder #1 on the engine. If you are up for going this method let me know. However you will need to rotate the large sprocket behind the large aluminum distributor housing in order to turn the injection pump without removing it from the engine.

Naj keep us up to date on the progress I can email photos and more information as needed. As most of you know from the tech session, I have take apart engines just a few steps from this computer.

Joe Alexander
Blacklick, Ohio

[Naj ✝︎]

Yes please, Joe,
 

quote:If you are up for going this method let me know. However you will need to rotate the large sprocket behind the large aluminum distributor housing in order to turn the injection pump without removing it from the engine

I would like to try this rather than remove the pump.
If I run the electriic fuel pump while trying this drip method, will it work?

naj

P.S:In the 230 parts list, there is a spacer washer behind the crank chain sprocket. Various thicknesses are listed. I assume this is to truely align the timing chain to the cam and auxillary sprockets.
The 280 list does not show this spacer  :?:
Seems like the chain picked up a bit of this washer but will see what it is when we strip further.

naj

65 230SL
68 280SL

[Naj ✝︎]

What's this?
Any clues?

Download Attachment: Tim_Gr02.JPG
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Crank sprocket


Download Attachment: Tim_Gr05.JPG
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naj

65 230SL
68 280SL

[Naj ✝︎]

OK simpler question:

#195 TOP timing chain sliding rail next to Mounting Bracket #216 - is it facing the right way or should the extension be facing upwards?


Download Attachment: TimCnh01.jpg
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naj

65 230SL
68 280SL

[enochbell]

It appears correct in the pic, orientation is with extension facing downward.

g

Download Attachment: IN02_0035.jpg
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'64 230sl, fully sorted out...ooops, spoke too soon

[A Dalton]

As the chain links pass over  the rails, they enter the heel of the  rail  first.
 Engine is CW viewed from front.

[Naj ✝︎]

Thanks Gentleman
That resolves an argument  

naj

65 230SL
68 280SL

[Benz Dr.]

Removal of the delivery valve holders means a calibration of the injection pump. Not a major one but you can upset the fuel delivery.
Can't set the pump timing without pulling it first. The drip tube method is basicaly useless for these cars. Diesels and 300 SL's are direct injection so timing is critical and adjustable.
Early crank gears had spacers and oil slingers but new ones don't.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
  1 877 661 6061

[Naj ✝︎]

Thanks, Doc,

quote:Early crank gears had spacers

Early crank sprocket with spacer:


Download Attachment: Tim_Gr14.JPG
32.98 KB

65 230SL
68 280SL

[Naj ✝︎]

Okay, to wrap up this thread, Itm 372, idler gear spacer broke (can't tell why) and got caught up in the chain.

http://www.sl113.org/forums/uploaded/naj/20051129145148_TimCnh01.jpg

Earlier thoughts were that I may have installed the top chain rail the wrong way round allowing the chain to whip about, but some pictures taken after the cyl head change show it correctly installed.

Could I have (inadvertantly of course) dropped  the spacer into the cavity? Do remebber checking but....
If, so, where was it for the last 500/600 miles the engine ran fine before getting caught in the crank sprocket (most damaged).....

Any thoughts  :?: [:0] :oops:  :?

naj

65 230SL
68 280SL

[Ben]

quote:Could I have (inadvertantly of course) dropped the spacer into the cavity? Do remebber checking but....
If, so, where was it for the last 500/600 miles the engine ran fine before getting caught in the crank sprocket (most damaged).....

........and thats a distinct possibility. It could have sat between the chain and the head somewhere ...............lying there........
waiting...............and then for no reason ...........BANG ![:0]

Regards,
Ben in Ireland.
'64 230SL 4sp.

[Benz Dr.]

There's no way that part can break or fall out. It must have fallen out when you pulled the shaft or put it back in. Did you pull the head or have the whole engine out of the car?
Normally, This part can stay in the head and I only remove it for cleaning or inspection. The spacer may have wedged into a chain rail and then finally dropped into the chain and crank gear. Are any of the chain rails damaged or the inside of the block/chain case worn with marks that would indicate where this part was caught? It's definatly a loose part and not on the shaft.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
  1 877 661 6061

[Benz Dr.]

Just had a look at all of these pics. How thick is the broken part? If it's about 5-6 mm it's the spacer. If it's thinner with a chamfer on one side it's not the spacer and is likely a head bolt washer that goes on top of a cam bearing. The hole through the centre is smaller and the whole piece is not as big as a spacer. The chances of a loose washer floating around on top of the head are far more possible and would be consistant with several hundred miles of driving before the big bang........

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
  1 877 661 6061

[Naj ✝︎]

Hello Dan,
 

quote: Did you pull the head or have the whole engine out of the car?
Normally, This part can stay in the head and I only remove it for cleaning or inspection. The spacer may have wedged into a chain rail and then finally dropped into the chain and crank gear. Are any of the chain rails damaged or the inside of the block/chain case worn with marks that would indicate where this part was caught? It's definatly a loose part and not on the shaft.

Yes, I swapped to a 250 head about 500/600 miles ago.
It is 5-6mm square section and seems to be the spacer. I have to agree, I could have 'inadvertantly' dropped it. Seems too strong to just break without any cause. Its interesting that they are no longer used on the 129 and 130 engines.
The longer chain rail cracked between pins but could not see any other markings in the chain gap in the block.
The pistons 'hit' two valves and bent the rocker fingers but did not bend the valves. (Joe explained this happened because the piston tops are flat and valves vertical. Luckily, too the cam support bearing posts did not break)

Download Attachment: Tim_Gr04.JPG
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naj

65 230SL
68 280SL