Head Removal and Rebuild - 230SL

[Harry]

I am in the process of removing the head on my 230SL for a rebuild and had a few questions for those who have already been down this road.  (I have also been reading various posts on this topic.)  The car has (shows) just under 100K miles miles on it.  I will check to see if the chain has ever been replaced (continuous or not) by looking for an installed (or not) master link.  Should I change the chain at this time.  I plan on looking at it and the CAM sprocket for general condition.
Also, it sounds as though I will need to support the chain from above the head while raising the head a little, then grabbing the chain below the head so that I can lift the head away?
What tools are used to depress the valves/springs so that the rockers can be moved away, so the valve keeper can be removed, etc?  I seem to recall seeing one that hooked under the camshaft and depressed the valve?  Are those available?
Many thanks!!

[Pawel66]

Harry, as for your last question - just to remove the rockers it is allen key No. 5. You are Full Member - take a look at valve adjustment tour in Tech Manual - lots of tips there, including the allen key trick. You do not need vice grips probably, you can do it by hand.

[mbzse]

What tools are used to depress the valves/springs.../... I seem to recall seeing one that hooked under the camshaft and depressed the valve?  Are those available?

The tool I use looks like this; bought on ebay

[Tyler S]

Harry, you can use a long zip tie attached to the unbroken chain and drop it down into the engine to get it out of your way. The ziptie will aid you to retrieve it during reassembly. Do not rotate your engine unless you have a helper to pull the chain back out of the engine or things will get ugly.
Be sure to set the engine to TDC #1 before disassembly. The tensioner, tensioner arm and sprocket, and cam sprockets need to be removed.
If the chain needs to be replaced, you can do that after the head has been reassembled and installed.

[Harry]

Thanks for the valuable responses.  The Valve Adjustment Tour was very helpful.  My father was always a big Mercedes fan so I grew up with many different models of these cars - 190SLs, 250SLs, 280SLs, the old diesels and various sedans.  We worked on them regularly and seeing some of the crowfoot tools reminds me of those days.  I have some of the specialty tools that Dad had including several Mercedes Benz offset wrenches and I remember the crowfoot tools but I'm not sure that I have those specific ones.
My take away is that I do need to get a tool to depress the valve/spring so that the rockers can be removed.  The #5 allen key can then be used to lift the rocker arm away.

I can't wait!  These cars were built like a tank and it's so cool to get into them and see German engineering at its finest.

Thanks very much.  I'm sure that I'll be back for more answers!
Harry

[Harry]

MBZE - could you provide me with the manufacturer and model number of your tool?  Or something that makes locating one a little easier?  I've searched based on a generic description but haven't had good results.

Thanks,
Harry

[mbzse]

.../... the manufacturer and model number of your tool?.../...

This is uk vendor as mentioned in the Technical Manual (Valve adjustment Tour, step 7b):
https://www.amazon.co.uk/Sealey-VS168-Valve-Spring-Compressor/dp/B000R9ZITC
You may find a US vendor for same or similar device

[Harry]

Thanks for the tool detail!

[Pawel66]

My take away is that I do need to get a tool to depress the valve/spring so that the rockers can be removed.  The #5 allen key can then be used to lift the rocker arm away.

I am not insisting or anything like that, but, in case someone reads it, who has e.g. simple valve adjustment job to do and will be puzzled/stopped by not having this tool: just for removing/reinstalling the rocker arms all you need is the allen #5. Did it several times while adjusting valves. The lever on the ballpin side is 3-4 times longer than on the valve side.

Of course it is much more professional and better for cams to use the compressor, especially if you do it frequently.

What I do not know is how you disassemble the valves when you have the head out on the bench already. I would imagine you need to compress the springs somehow - that is when this kind of tool is necessary, I guess. Never seen it done, actually...

[Harry]

Pawel66,

Are you saying that the rocker arm can be removed without depressing the valves?  It looks as though it would be trapped between the ball, the cam and the valve.  Not the case?

Harry

[Pawel66]

You make sure the cam is up over given rocker. You take the allen #5. Stick the shorter end in the lubricating hole of the rocker (above the ball pin). Grip the longer end (can use vice grip, I did it just with my hand). Lift it (you now are depressing the valve - a very efficient lever is created now). Move the end where you stuck the allen to the side. Take out the rocker. It is about 3 seconds operation.

I found it on this forum, I did not invent it myself (unfortunately  ).

[Harry]

Surprising!  I just would have intuitively considered that the valve spring would be more difficult to overcome.  I ordered the tool (not too expensive) but I'm anxious to try this as well.  Thank you very much!

[Pawel66]

And you did a good thing on buying the tool. I was just too lazy...

I had work to do on cam shaft, tappets, shims under cam shaft pedestals etc. I was studying the forum carefully, noting every tip. This allen exercise was just there. As an extension of the Tech Manual tip. Actually I thought everybody knew about it even though professionals might not use it.

You have 230SL with, maybe, older type of rockers - I did the rockers of a new type, I hope the lubricating holes in them are the same.

If you do have the old type of rockers, you may want to look at some of the threads on this forum suggesting caution to leave proper distance between the bottom rocker arch edge and the top spring holder. If the angles are not correct, the rocker may be tapping the holder instead of the tappet, leading to catastrophy. It is far ahead of you, but you may want to remember about it and, in case you will not be replacing the rockers (replacement would be for a new type), make sure the distance is there.

I mention this as this may be one of the pculiarities of these engines not commonly known and not likely to be asked about.

There is A LOT here about heads rebuilds, I saw it when I was looking for stuff about valves. Timing chain change procedure is here too in case you have to do it. Chain tensioner set up as well. Those really helped me a lot.

[Harry]

Pawel66 - thanks again.  I’ll get busy with more research.

[Harry]

I’m ready to remove my chain tensioner and have eveything set to TDC but I’d also like to remove the injection pump.  It sounds as though I need to set the timing to 20 ATDC, remove the IP, reset the timing to TDC, then remove the tensioner and head.  Sound correct?

Thanks,
Harry

[ja17]

Make sure your at TDC on the compression stroke #1.  Distributor rotor should be pointing to #1 plug wire and the front two cam lobes are upward.

[Tyler S]

Setting the timing to 20 ATDC is only for Installation of the IP after your engine is back together. Do not use this setting for any other procedure.

[Harry]

So just to be sure, I will set timing to o degrees top dead center based on the timing mark and the distributor button pointing at number one plug wire position (mark also on distributor case).  I can then remove the IP and the head.  No need to locate 20 degrees ATDC for IP removal.  Sound correct?

Thank you,
Harry

[Tyler S]

Yes that is correct.

[George Des]

The Haynes manual shows how to make a valve spring depressor out of a section of box steel readily available at Home Depot, Lowes or ACE Hardware. Some cuts with a grinder cutoff wheel and you have a cheap, effective albeit not elegant valve spring deptessor tool.