Valve Adjustment Tour

[66andBlue]

.... In addition Alfred and myself have been gathering information and photos for a good "valve adjustment tour" coming your way soon...

Hello everyone,
the time has finally arrived - Joe and I finished the write up and here it is for your enjoyment, critique, and/or additions and corrections.
However, I should make it clear: I was mostly the scribe, photographer and illustrator - I have never loosened a cylinder head bolt in my life!
So, please address all technical questions to Joe and others to me.
Also, since one can only have four attachments per post I'll have to cut it up into three.

We'll place the complete tour also into the Tech Manual soon, including higher resolution pictures.
Thanks!
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W113 Valve Adjustment Tour
Part 1

Adjusting valve (tappet) clearances is part of the Plan E maintenance schedule of our cars and should be performed every 12000 miles.
 
The valve adjustment procedure is briefly described on pages 00-3/1 to 00-3/3 in both sets of the BBB, that is, for cars starting in 1959, which includes the 230SL and 250SL, and those starting in 1968, which covers the 280SL model.

Other maintenance jobs to consider during this procedure:

   

• Check Rocker arms
     Re-torque Cylinder Head Bolts
     Check for Timing Chain Wear
     Check Vertical Timing Gear
     Check Resistance of Spark plug Wires and Ends
     Replace Spark Plugs

Attention:
Should you decide to check the tightness of the cylinder head bolts and re-torque them to specifications – as described below - the engine must be hot.  If you plan to skip this task then be beware that valve adjustments are done on a cold engine. 
Therefore, if both procedures are planned start with the engine hot to perform the head bold adjustments and after the engine has cooled off adjust the valves and complete any of the other maintenance jobs.
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Terminology
1. Left and right are determined by standing at the rear of the car and facing forward
2. Front or forward mean toward the forward end of the car, rear or rearward means toward the rear.
3.  Torque is defined as force times the length of the lever arm (radius).
Torque units in the BBB are stated in mkp (kilopond-meter).
Conversions:
1 mkp = 7.23 pound-feet (lb-ft)  = 86.8 pound-inch = 9.81 Newton-meter (Nm)
1 Nm = 0.738 pound-feet = 8.85 pound-inch = 0.102 mkp

Tools needed:

1. 1/2” ratchet with diverse metric sockets
2. 10mm hex (Allen) socket, 10mm and 13mm wrenches.
3. ½” torque wrench (0 – 150 lb-ft)
4. 17mm (for 280SL) or 14mm (for 230SL) special valve adjusting tool
5. Feeler gauges: 0.8 mm (0.003 inch) and 0.18 mm (0.007 inch) thick, 10 mm wide.
6. Flat-tip and Philips screwdrivers.
7. Remote starter switch (optional).
8. Fender protection blankets.

Parts and Supplies needed:

1. Cylinder head (valve) cover gasket, 1 each [p/n 130 016 02 21].
2. Copper seal (crush) rings (ID: 8.5mm; OD: 13.8mm) for cover bolts, 3 each [p/n 007603 008 303 – note:  this p/n is currently not stocked by US – MB dealers and is substituted with p/n 007 603 008 403, a slightly flatter crush ring].
3. Spark plugs, 6 each (optional)
4. Grease
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A. Removing the Cylinder Head Cover (Valve Cover)

1. Protect your fenders with covers. No matter how careful you think you will be, accidents always happen. There is no need to take a chance on damaging your paint.

2. Snap off the three linkage rods [1] on the transverse control shaft [2] shown in Figure 1.  Facing the left side of the engine remove the shaft by unscrewing the two centering nuts on the front of the bearing bracket [3] and pull the shaft out of the rear bracket.  During re-assembly always install centering nuts with the tapered side towards the bracket!



3.  Next remove the vacuum hose [4] between the intake manifold and the brake booster and disconnect the metal breather tube [5] from the rubber hose, but be careful, all the attached plastic parts become brittle with age.  Leave the rubber hose on the cover.

4. Remove the three bolts holding the valve cover in place and lift off the cover along with the rubber gasket and set it aside.  If difficulties are experienced clearing the hood latch on the firewall you may need to elevate the rear of the engine slightly. Use a floor jack and a block of wood at the engine/transmission junction and raise the engine just enough to do the job. 
Inspect the gasket for nicks and tears and give the gasket the “bend test”, that is, bend it into a tight radius. If it is brittle and breaks, replace it!

5. Examine camshaft wear (flat spots or wear spots through hard coat) [Fig. 2].

6. Check that there is sufficient clearance between the camshaft and the three straps to which the valve cover was attached.

{Parts 2 and 3 to follow}

[66andBlue]

Valve Adjustment Tour Part 2.

B.  Basic Valve Adjustment for W113 Engines

First identify the intake valves and exhaust valves – confusing them will be dangerous to your engine’s health.
The six exhaust valves are on the left (spark plug) side of the engine [Fig. 2] and the six intake valves are on the right side where the exhaust manifold is attached. The adjusters for each valve, however, are on the opposite site.



There are several ways to turn the crankshaft to position the cam lobe correctly over a particular valve [Figure 3].

(a) Remove the spark plugs and then turn the crankshaft at the bolt that fastens the Veepulley and the counter-weight to the crankshaft.  Use a socket (22mm for 230SL and 27mm for 250SL and 280SL) and a ratchet to turn the crankshaft in the direction in which the engine turns. If the car has an automatic transmission put it in “Park”, if it is has a manual transmission put it in “Neutral”. A strap wrench on the crank pulley may work also but make sure you remove any wrench before trying to start the engine again! Taping a reminder to the steering wheel is not a bad idea.

(b) An alternative method if you have a manual transmission car is to put it in 4th gear, jack up driver side rear wheel, block the other wheels, release the hand brake and turn the raised wheel forward while observing the cam sprocket. Make sure your engine is turning in the normal direction of rotation!

(c) Finally one can turn the starter on and off briefly until the camshaft gets into the desired position.  However, rather than using the ignition key it is much more convenient to use a remote starter switch [Fig. 3a].  Attach one lead to the + pole on the battery and the other to the “G” terminal of the thermo time switch [Fig. 3b,c] to engage the starter.  This is by far the most convenient method.


Caution: Do not rotate engine using the hexagon bolt on the camshaft [Fig. 3d] no matter how convenient it appears!

1. Turn the engine until the base circle of the cam is against the surface of the rocker arm of valve number 1, the cam lobe is in the opposite orientation facing upwards, and the valve is fully shut [Figure 4b-d].


2.  Once the cam lobe is in the proper position it is rather easy to adjust the valve clearance provided the appropriate wrench adapters are available [Fig. 5b]. Stuck ballpin adjusters or damaged ones with rounded hexagon collars may require a ½’ drive six-point socket to free.  However, the rocker arms prevent direct access of a socket to the hexagon collar of the ballpin head [Figures 4c and 5a] unless the rocker arm is removed (see procedure below).



Fig. 5b shows a variety of crowfoot adapters useful for this job. The 230SL (M127) requires a 14mm adapter and a 17mm adapter is necessary for the 250SL (M129) and 280SL (M130).

The correct position for measuring valve clearance is between the base circle of the cam and the sliding surface of the rocker arm as shown in Fig. 4c and 4d.  Use a long, flexible wide-blade gauge and make sure the feeler band goes all the way across the rocker arm surface [Figures 4d, 5d].

The correct clearances are 0.08 mm (0.003 inch) for the intake valves and 0.18 mm (0.007 inch) for the exhaust valves.

Adjust the valve clearance by turning the ballpin head at the hexagon collar by means of the adapter and a torque wrench (0-6 mkp). To loosen valve clearance turn the hexagon collar clockwise, to tighten turn the hex collar counterclockwise [Fig. 5c].
With the feeler blade inserted tighten the hexagon collar (ballpin adjuster) until the blade is locked, then loosen the adjuster until the blade can be pulled through. The clearance is adjusted correctly if the feeler band can only just be pulled through.  When the ballpin hexagon collar is turned into the base the adjusting torque must be at least 1.5 mkp (11 lb-ft).  If the adjusting torque is less, either the ball pinhead and/or the pinhead base must be replaced.
By following the firing order, that is, adjust number 1, then 5, then 3, then 6, etc  [Fig. 2] and watching each lobe as it comes to vertical, all 12 valves can be set in two turns of the engine.  Prepare a chart and check off each valve as it is adjusted.  It is useful to record the clearance value before and after the adjustment in the chart to see whether a pattern develops over time indicating a potential problem.

[66andBlue]

A corrected Figure 8 was added on Feb. 5, 2009

Valve Adjustment Tour Part 3

C.  Removing a Rocker Arm

The procedure to remove and install rocker arms is described on page 05-1 in the 230SL Service Manual or on page 05-2/1-2 in the 280SL Service Manual. It requires a special tool to compress the valve springs in order to free the arms.  


Figure 6.

Those made by Mercedes (p/n 1111 589 01 61 or 112 589 61 00) [Figure 6] are no longer available and used ones have become very rare and expensive.  Fortunately, similar tools are readily available from several suppliers, for example, in the USA Samstag Sales carries an Esgen universal valve spring compressor (Mark-Line p/n 13168) and in the UK Sealey Power Products has a similar tool (Product code VS168) shown in Fig. 7b.
Added Aug. 2009:  The inner radius of the large hook that comes with Esgen tool is too small and does not fit under the camshaft.  It needs to be enlarged.




1. Turn the engine as described above until the rocker arm is not under load.  Force the clamping spring [Fig. 7a] out of a notch at the top of the rocker arm and move the spring outwards to free it from the rocker.  Use an appropriate tool and force valve down to remove load from rocker arm [Fig. 7b]. If the downward movement of the valve stops abruptly during this process, turn the engine slightly since the valve must be contacting a piston.  Lift the rocker off the ballpin, using a hex key as shown [Fig. 7c] and store it in a clean place.  If more then one rocker arm is removed store them all in the correct order for reassembly – do not mix them up!

Ballpins with damaged or rounded hexagon collars can now be freed using a ½” drive six-point socket [Fig. 7d].

Before re-installing check the sliding surfaces and the ball cup of the rocker arms.  Damaged arms should be replaced.

To re-install the rocker arms reverse the process.

Check valve clearance again and adjust if necessary!

D. Loosen and Tightening the Head Bolts

"To Torque or Not to Torque" that is the question?

Some owners and mechanics cringe at the thought of loosening a head bolt on a perfectly good engine for the sake of re-torqueing it to specifications.  Horror stories of rounded head bolts, snapped-off broken head bolts, rusted, stuck or leaky situations spread fear and apprehension into the minds of some.

Early Mercedes-Benz Workshop Manuals indicate that cylinder head bolts should be checked and re-torqued at certain intervals:
*December 1959 Mercedes-Benz Workshop Manual Type 190 pp. 01-3/2 ; the standard procedure at the time for a valve adjustment at every 12,000 miles was to: " 1) remove air intake silencer and cylinder head cover. 2) Check tightness of cylinder head bolts and if necessary, tighten as specified" …*

This information is not repeated in later manuals.  Mercedes Shop Manuals are like a soap opera - you need to know what happened in the previous edition to get the complete story. New manuals often start off where the last one ended on certain subjects. The engines in the W113 cars and all Mercedes engines up till the late 70's used the same configuration for the head bolts and basically the same materials in the head gaskets.

It is easy to understand how a head gasket, which is subjected to years of use and thousands of heat cycles, can compress and allow the cylinder head to become looser than specified.
Over my forty plus years of working on these engines I (J.A.) have found this is exactly the case. Even though the engine head bolts require more than specified torque to loosen, they nearly always pull down past their original positions to reach specified torque. Engines that have never been re-torqued are more prone to head gasket failure and leaks. These engines may have very loose head bolts or actually seized head bolts from coolant leaking past their head gasket and into their threaded holes where corrosion results.

Over the years re-torqueing has been adopted as a standard practice by some and avoided by others.
You will find arguments on both sides for sure.

Now, if you start this task be beware: Head bolt re-torque is best done on a hot engine.
Warning: loosen coolant cap to relieve pressure first!


There are seven head bolts on each side of the engine for a total of fourteen [Fig. 8a].




1.  Remove sludge and other debris from each of the sockets [9a].

2.  Use a high quality, long 10mm Allen (hex) wrench (key) and a long-handle ½” ratchet or breaker to loosen the head bolts and keep the Allen wrench straight to prevent rounding the socket [9b,c].  Expect to use lots of force – often 50% more torque than required for tightening!
Sometimes the valve cover straps tend to twist during the loosening procedure.  If that happens wedge a suitable metal piece between the strap and the next rocker arm to prevent twisting.  They can be straightened again after the bolt is loose.

3. Loosen cylinder head bolt number 1 as shown in Fig. 8b at least one full turn or more, then re-torque it to specifications.  WARNING: Never release all bolts first prior to tightening!

4. Loosen cylinder head bolt number 2 and re-torque. Continue loosing and tightening all bolts progressively in the order shown in Figure 8b.

Torque specifications with hot (>80° C/ 176°F) engine:

230SL (M127) and 250SL (M129): 9 mkp (65 ft-lb)
280SL (M130): 11 mkp (80 ft-lb)

E. FINISHING UP

IMPORTANT:
After completion of adjusting jobs check all clamping springs for correct seat.
Use jump-start cable [Fig. 3a] and crank engine a few a times.

Mount cylinder head cover, watching out for correct seat of cylinder head cover gasket.  
If possible use new copper seal rings (crush washers) for the three hex bolts that fix the cover to the three camshaft straps.

Do not over tighten these valve cover bolts or the straps will bend inward contacting the camshaft and causing a severe clattering noise.

Connect all linkages, vacuum line and breather tube.

Run engine and check cylinder head cover for leaks.

{THE END}

[ja17]

Hello,

A correct vavle adjustment tool or crow's foot should be thicker than a normal crow's foot.  This allows more surface area against the hex collar (ball pin adjuster) and is less likely to round off the adjuster. If you use a standard crow'w foot or wrench, you will have a little more tendancy to round off the adjusters. Sometimes they are just stuck from years of no adjustment and you will have to remove the rocker and at least break them loose with a six point socket. After this the adjuster tool will normally be able to adjust the hex collar (ball pin adjuster) again.

[wwheeler]

Thank you Joe and Alfred for your work on this. I think you both did a fantastic job.

This is a straightforward but critical maintenance job that most people can do with good instruction like this.

Quick question: What torque do you put on the valve cover bolts?

[66andBlue]

Hi Wallace,
thanks for the accolades. 
Awhile back Jaco ("jacovdw") wrote that he uses 5 Nm on his 230SL and that up to 10 Nm on a 280SL would be OK. He found the torque values in the W114/115 Service manual (5 Nm). Since the bolts and the valve cover towers (A115 xxx xx xx part number) are the same as used on the pagodas he concluded that the torque values would be the same.
I believe Joe does it by "feel", but I let him explain this.

[jeffc280sl]

Fantastic writeup and pictures.  Thank you very much!

BTW, your engine is sweet

[66andBlue]

Thanks Jeff!
My car's engine is shown only in the first picture in Part 1 (230sL). The other pictures are from a 280SL that Joe has taken care of for 30+ years. Here is a picture of the car and the owner taken at the last PUB.
Are you coming to the PUB this year?

[ja17]

Hello,

One other note,  if you find that any valve is way out of adjustment (one turn or more), remove the rocker and check the contact surface of the rocker arm. Most likely it has a worn flat surface.  The rocker  arm contact surface is case hardened as is the camshaft. Once the hardened surface is gone, rapid wear results!

[glenn]

Re: Rocker arm removal/valve spring compressor tool - Fig 7b.  Will bring a handy-dandy STM(Shade Tree Mechanic) tool to  PUB 2009. 

[Eminent]

Indeed. A very nice walkthrough.
Compliments to the makers of it.
Though, there might be one thing that people may confuse.
The text says that the remote starter must be connected to terminal "G" from the thermo time switch.
Pictures are pointing at terminal "W".
Not a very big issue but a bit strange.
Keep up the good work.

[66andBlue]

... The text says that the remote starter must be connected to terminal "G" from the thermo time switch.
Pictures are pointing at terminal "W"....

Hi Eminent,
that would be strange indeed. However, looking at Figure 3 in the "tour" (see: http://www.sl113.org/wiki/Restricted/ValveAdjustmentTour) I notice two arrows pointing out terminals G and W. 
Where did you see this?

[Eminent]

I see it in this topic, fig.3B and 3C. I'm not a full member (yet) so i don't know how it is in the restricted area.

[Iconic]

The text says that the remote starter must be connected to terminal "G" from the thermo time switch.
Pictures are pointing at terminal "W".
Not a very big issue but a bit strange.
Keep up the good work.

At one time I was confused by this also, but, I believe it was all correct and the confusion lies with the shape of the plastic.
See my post on the subject.
http://www.sl113.org/forums/index.php?topic=10756.msg71626#msg71626

[66andBlue]

Do not use the plastic wedge to determine which pole is "G" or "W". Simply find the smaller one of the two and it will be "G".

[glenn]

Valve adjustment in one cam shaft rotation:       (in order of rotation)  Keep for your records.
                                                                      .003 on In       .007 on Exhaust
           VALVE ADJUSTMENT
              Date      Date      Date
              ____      ____     _____

1 Ex       _____

4 In       _____     

5 Ex       _____

1 In

3 Ex

5 In

6 Ex

3 In

2 Ex

6 In

4 Ex

2 In

[tel76]

In the reply #1 of the Valve adjustment tour, part 2, Basic Valve Adjustment, you show a photograph of the camshaft,timing wheel and camshaft tensioner/slipper.
Is the tensioner/slipper fitted upside down?
The reason for asking this question is that i have just dismantled my engine and was fitted with the long part down,if you look at the illustration of the tensioner/slipper in the SLS parts page it also shows it inverted.
I have also received a new slipper from MB and it is a very flimsy plastic part.
What should we look for in the original part that would render it unserviceable.

[glenn]

PPP (Previous Possessor Peccadillo)

tel76, Good eyes!!  Top slipper should go down?  Bottom one goes up?  Same guy put the caliper vents on the bottom. ..

The two ridges in the plastic slipper should both be there. ..

A note on the VAT?. ..

[ja17]

Hello,

Yes as far as I know these chain rails were always meant to be installed downward as in photo 3d

[tel76]

Hello Joe and Glenn,
Are you both in agreement with the lower one facing up, whilst the top one was installed correctly,the bottom one(small one) was facing down.

[glenn]

tel76, My understanding is the slipper mounted on the head should point the long end down.  There are two slippers in the block.  The short one on the chain's outside should have the long end pointing up.  The long one on the chain's inside is centered, I think.  The slippers each have two (plastic) ridges that should be intact.  The chain tensioner and the slippers act together to stop chain flapping.   Be sure to 'prime' the tensioner with oil before running the engine(see manual).  Cheers!!. ..

[tel76]

Hello Glenn,
I have today removed both lower slippers(large and small) for inspection, the small one fitted on the left hand side has to be fitted  long end down(as it was fitted prior to my removing it).
As an experiment i tried to fit it long end up and the pins would not line up.
All three slippers have the ridges complete so i will refit them when i rebuild the block,rather than use the latest MB flimsy items.