Rodd's timing chain replacement

[ja17]

I finished this thread and added to the original message several times to keep it all together. So here is fairly comprehensive document on "timing chain replacement". Feel free to comment or add to the string.

Download Attachment: chain a begin.JPG
58.66 KB (Rodd Masteller and his 230-SL)

We replaced the timing chain in Rodd Masteller's 230-SL last week-end. We took some pictures and documented the process for the group. We will describe the process here during the next few days.
Replacing a timing chain is not that difficult, but the consequences from making a mistake can be catastrophic. We suggest that first timers may not wish to attempt this on their own. One should at least get help or guidance by an experienced technician on the first attempt.
Step number one get the right parts.  A valve cover gasket, and valve cover bolt seals should be on hand. The spark plugs will be out so decide if you may wish to replace these also. All W113 engines used the same chain. Part numbers would be nice to add to this document.
Have the correct tools; 27mm socket(22 mm on early cars), a two or three inch extension and a 1/2" rachet handle  for turning the crankshaft. A spark plug removal tool.  A couple of locking pliers (Vicegrips) are helpful. Assorted metric wrenches (14mm early cars) 13mm, 10mm, a die grinder or Dremel tool to grind off end plates of chain (original chains had no masterlink). Some good strong bare wire to tie off chain ends(wire coat hangers work fine). One or two helpers (at critical times)makes the job much easier.

It is a good idea to disconnect the battery to prevent any accidents.
Remove the crossover linkage by popping the linkage rods going to the injection pump, venturi and accelerator. Next the two 10mm nuts holding the crossover linkage rod in place are removed (notice that these are special 10mm "self centering" nuts, the cone shaped sides must be oriented against the metal during re-assembly). Next the entire crossover linkage rod can be popped out of it's socket on the intake and removed.

Notice that Rodd has popped the intake side of the "crossover linkage"  out of it's socket.
Download Attachment: chain b remove linkage.JPG
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Remove the spark plugs so that the engine can be turned easily by
hand.

After the valve cover vent tube is disconnected and the three valve cover bolts are removed the valve cover is ready to be lifted off. If the valve cover will not clear the hood bracket on the firewall, the engine may have to be lifted with a jack under the bellhousing.

Download Attachment: chain c remove valve cover.JPG
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The 27mm socket (22mm on early cars) and extension can be fitted on the crankshaft bolt. A 1/2" ratchet handle is fitted to turn the engine by hand. One person working from below and another above is best. Always turn the engine in the normal rotation. Original undisturbed chains had no masterlink and must be broken. Replacement chains have masterlinks.

The chain tensioner sprocket will be visible directly under the camshaft sprocket. The chain tensioner acts on this sprocket to take up normal chain "stretch" or wear over the years. Eventually it extends to its limit and no longer takes up the slack. This tensioner is spring and hydraulically tensioned.
A chain link will have to be broken if no master link is found.
The exposed engine  must be protected from any contamination. Download Attachment: chain d grind ends of chain link.JPG
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A air die grinder or Dremel tool can be used to grind off the chainlink pins.

Download Attachment: chain e secure ends of chain.JPG
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 Be sure to keep track of the center plate of the link, it will be loose and it could fall into the engine.
Download Attachment: chain f split chain.JPG
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After the chain is broken, hook a wire to the tensioner side of the chain for pulling. Hook the new chain to the distributer side of the old chain. In addition hook a wire to the other end of the new chain for use later.
Download Attachment: chain h feed new chain.JPG
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The new chain must be kept in contact with the chain sprocket on the engine so valve timing is not lost. Rodd worked from the intake side of the car. One hand held the new chain tightly against the chain sprocket while the other hand kept tension on the old chain so it would not bunch up and jamb. I slowly turned the crankshaft with a ratchet.
I like to use some Vice Grips to hold the chain tightly in place during the link removal.
Eventually the end of the new chain emerged from the engine. The extra length of wire hooked to it's end became very useful at this point. You want to make sure to always have a firm grasp on both ends since it can be unexpectedly yanked out of your hands at any time.
The new chain will seem too short to connect at first. The chain tensioner must be manually depressed by a steady downward pressure on the tensioner sprocket  until the ends of the new timing chain are close enough to connect with the new master link.
Download Attachment: chain h new chain in place.JPG
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The master link may be the single clip type, the two "c" clip type or the "crimp" style. The first two styles require only no special tools. The crimp style which is becoming more common, require a special crimping tool or must be peened. Be sure to check the master link to see which style you have before beginning.
The two new chain ends are again clamped to the chain sprocket with vice grips or wire. The new mastelink is installed from the front the center plate is a bit thicker than the end plate and it is installed next and lastly the endplate and clip or clips are installed.
Download Attachment: chain i connect ends of chain.JPG
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Crimp or peen the mastelink pins if you are using this style of masterlink.
The valve timing should always be checked before finishing the job. We turned the engine at least one more revolution by hand to make sure that the alignment notch behind the chain sprocket aligned with the mark on the front cam tower when the engine reached "0" or TDC #1. The valve timing must never be the slightest bit early! It is normal for it to be slightly "late" depending on the condition of the timing chain and cylinder head. Download Attachment: chain j check  camshft timing.JPG
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Do not ever be tempted to start the engine or crank it with the starter until the  camshaft "valve timing" is checked. If the camshaft timing is off the timing chain must be parted and reset.
Before putting everything back together we decided to check Rodd's  verticle timing gear and found that it had excessive end play. We removed the bronze/aluminum bushing and found it worn.Download Attachment: chain k check timing gear.JPG
63.86 KB We shimmed the gear using a brass injector seal. We re-asembled everything in reverse order.


Joe Alexander
Blacklick, Ohio

[Joe]

OK, I'll ask.
1) How does one know he needs a new timing chain?
2) Wouldn't this job be considerably easier with the hood removed?
Joe

[rwmastel]

1) About a year ago I took off my valve cover at Joe's place.  He looked at the chain tensioner and noted it was completely extended.  If the chain stretched more, it would be loose and possible skip a tooth on a sprocket.
2) Maybe a little easier, but not much.

I'll post some more pics and text later, been too busy this week.

Rodd
1966 230SL Euro
1994 E420

[Tom]

Joe,

Indicators that your timing chain is stretched can be found by setting your distributor at top dead center and ensure the #1 piston is at TDC.  At this point, the notch in the sprocket on the cam will line up with the notch on the cam, and the rotor on the distributor will point to the notch in the distributor housing (have to see it to completely understand).

Most cars that have not had a chain replacement after 30 years will not line up.  Up to 3 degrees, its probably fine, but more than 3 degrees off generally is a sign that the chain is stretched, sprocket is worn, etc.  This can be adjusted with a woodruff key, but given the catastrophic damage if the chain breaks, most people recommend that the chain be replaced.  You will note a boost in performance once the stretch is gone and the timing is lined up.

Best,

Tom

[ja17]

Hello Tom,
These are all good answers. As a general rule of thumb at 100,000 miles these chains are ready to be replaced. If you do not have any mechanical history  of the engine you may have resort to removing the valve cover as Tom and Rodd have mentioned and look at the chain tensioner sprocket to see if it has extended to its limit, or review the timing marks. Timing marks can also become out of sync by cylinder head resurfacing, which shortens the heighth of the head.
I will try to add some more information to Rodd's timning chain thread latter this evening.

Joe Alexander
Blacklick, Ohio

[rwmastel]

Here's how we did it, pardon me if my terminolgy is not 100% accurate
- Have an experienced person lead  
- Disconnect battery
- Remove spark plugs (read their condition, gap them)
- Remove spark plug wires (test for resistence)
- Pop three linkage rods off main crossover linkage rod
- Pop end of crossover linkage rod out of socket
- Remove two 10mm self centering nuts from crossover linkage rod bracket, remove
- Disconnect brake vacuum line
- Disconnect valve cover breather tube
- Remove three valve cover bolts and lift off valve cover (very tight fit between F.I. lines in front and hood catch in rear)
- Protect open engine
Download Attachment: Protect exposed engine.jpg
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- Lightly clamp chain to sprocket on two sides, we used vise-grips
- Grind ends of link pins off
Download Attachment: chain3a.jpg
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- It should look like this
Download Attachment: chain4a.jpg
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- Pull out link pins and take care not to loose the center link plate.
- Put new chain onto old chain using this link pin
- Put a pull wire through the end of the old chain
- Unclamp chain and have one person turn the engine with a socket wrench in the normal rotation of the engine.
- As the engine turns, pull the old chain through with tension so it stays on the sprockets.
- Let the new chain feed through.  Keep pressure on the new chain at the cam sprocket so it does not skip a tooth.
Download Attachment: chain5a.jpg
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- When the new chain comes up, get both ends clamped on the sprocket before you remove the link holding the two chains together.
- Seperate the chains, don't drop the center link plate.
- Connect the two ends together with the master link that came with the new chain.
- Make sure the clip's closed end is oriented to move in the direction the chain turns.  In case anything bad happens in the future, if it hits an obstruction it does not push it off the link.
- Check the timing mark by the cam sprocket and compare it to the timing mark on the crankshaft wheel and the location of your rotor in the distributor cap.  These should all be oriented correctly, I will let others describe that part.
- Correct timing if necessary.
- Reassemble everything in reverse order.

I hope this helps someone get the job done.  The single most important factor in getting this done right was experience.  If you are a novice, don't have another novice help you.

Thanks,

Rodd
1966 230SL Euro
1994 E420

[Naj ✝︎]

Off topic but:
Are the hose clips correct for 'radiator' hoses?
naj

naj
'Kloines Scheisserle'
65 230SL
68 280SL

[erickmarciano]

how do I adjust the mark on the cam if it is off once i change the chain?
thnaks

1971 280sl
1962 VW
1954 Allstate vespa
1958 gs150 vespa
1962 gs160 vespa

[ja17]

Hello Erick,
Offset cam sprocket keys are available from Mercedes. It will not  make a noticable difference in how you engine runs in most cases.
However the offset keys are available; # 621 991 0467   (4 degrees), #621 991 0267     ( 6 1/2 degrees), #621 991 0167 ( 8 degrees), and 621 991 0067 (10 degrees).  One link of the timing chain is equal to about 18 degrees of cam timing. It is ok for the cam timing to be a little late, but NEVER even a tiny bit early!  Check everything by turning the engine once or twice by hand before starting engine.

Joe Alexander
Blacklick, Ohio

[erickmarciano]

can I just move the cam if the chain is off?

1971 280sl
1962 VW
1954 Allstate vespa
1958 gs150 vespa
1962 gs160 vespa

[Cees Klumper]

Reviving an old thread. I used Joe and Rodd's instructions from 13 years ago to replace my timing chain this morning. I did some things differently: since I was by myself, I wanted to move the chain from above, using the camshaft nut, rather than the crankshaft bolt from underneath. To make this possible, I removed all the rockers in addition to the spark plugs, so there would be minimal resistance while turning the camshaft to thread the new chain through the engine.

My big mistake was allowing the chain to fall into the distributor side of the engine, but fortunately with a telescopic magnet pickup I was able to retrieve it. Keeping tension on both ends of the 'linked-together-old-and-new-chains' I was able to thread the new one through the engine fine.

I checked the engine timing twice, by rotating it from below, clockwise, as one should. The timing marks on the camshaft and the crankshaft lined up perfectly both times.

I reset the ignition timing and went off for a test drive. The car does seem to run stronger (although this could just be 'between the ears'). The biggest thing is piece of mind, as the chain was the one thing not replaced on this engine, when Joe and I rebuilt it in 2003.

[ja17]

Hello Cees,

It is hard to imagine that we did not replace the chain back then? It is an automatically replaced item during a re-build.  It must have been fairly fresh at the time? Glad to see your still motoring along.
 

[Cees Klumper]

Hi Joe, yes, we wanted to replace the chain then, but it was ln backorder and we didn't have the time to wait for it. I've not driven the car all that much since 2003 I have to say, but it's nice to have it finally done.