Camshaft wear

[SteveK]

I've been adjusting my valves and have found that on the small lobe of the number 4 intake and the number 6 exhaust there is significant wear.   Each one has a landing of between 10 and 20 mils worn away.   (I tried to take a picture but their too blurry with the close up)   No apparent wear on any of the large lobes.   The engine runs fine, a little rough at idle but no problem at all when it comes to acceleration or power. 

I did a quick look on the web and could not find anyone selling new cams.  So I have a few questions:  Is this a common issue?  (I looked in the search function and did not pick up a lot of discussion).  What would cause it on just two lobes?   Who sells new camshafts for a 130 engine?

Thanks in advance!

[Cees Klumper]

Hello Steve - SLS in Hamburg sells new cams, I bought a euro-spec from them a few years ago (and still have to put it in ...). Undoubtedly the other 'usual suspects' should be able to source one for you.

As far as I know, once the hardened surface becomes worn on a lobe, wear increases very quickly after that, so better keep an eye on it.

[wwheeler]

I was just doing some valve work on my M130 and saw this thread. I am replacing some of the ball pins and therefore and removing the rockers arms. When I inspected the arms, a couple had pits on the wear surface to the cam (see pic). I don't believe these pits were chipped but rather were casting flaws that did not "clean up". The pits are about 1/32" deep. First question is, should these be replaced?

The other question is that on the corresponding cam lobe to these pitted arms, there is a small (1/8)" in diameter dark spot (see pic). From what I have read from other threads, this could be a spot where the hard coating has worn away. Where the dark spots are, there is no material removal but more like a stain. Also the dark spots on the cam line up exactly with the pits are on the rocker arms. Is this a problem?

Thank you for your input.  

[SteveK]

After reading more of the forum history and calling around, I decided I had no choice but to change out the camshaft and all of the rockers.   Turns out the Classic Center had the best price on the camshaft ($525 after our discount).  Their price on the rockers were very high so I ordered 12 from one of the internet house's that has done very well for me in the past.  What concerned me most was what Cees suggested in that once this erosion starts it can progress fast and my fear was what happens to the fillings that come off the lobe. (could only lead to bad news).

So once all of the parts show up in a few weeks, I'll tackle the job.  I do have a valve spring compressor and a new valve adjusting tool.  Any one know of anything else special I might need for the job?

[lurtch]

Hello Steve,  - -  Check out the cam lobe wear my engine had.

This deterioration is caused by the ball stud adjuster nut losing its locking  ability. When it can slip off its setting,  it will back off and change  your clearance.  The valve clearance  will then eventually  diminish to nothing and by then there is not even enough clearance to allow an oil film to deposit on the rocker face.  - - -   Simple solution: BE SURE you change out the ball studs when you do the rest of the job or you will not have corrected the problem. There is break-away torque value for the ball stud in the BBB.  I learned most  all this from the info on this website.

Good Luck,  Larry in CA

[Dave Gallon]

Just for reference, there are four different camshafts (plus additional variations) present on the M130E. The camshaft journal diameter changed at engine 130.983-10-004596 and 130.983-12-007229. There were also different versions for the US market and non-US market. The non-US market camshaft is often referred to as the high-output cam as it has more valve overlap and results in more horsepower. The four camshafts are:
US, 1st version: 180 051 08 35
US, 2nd version: 114 051 05 01
non-US, 1st version: 180 051 09 35
non-US, 2nd version: 114 051 02 01
However, the non-US 1st version camshaft is not available and has been replaced by the second version. This means that installing the high-output cam in an early engine requires replacement of the camshaft bearing towers (114 586 04 05) as well. To the best of my knowledge, the three camshafts are available as is the camshaft bearing kit. If you would like a quote of price and availability on any of these parts, please send me a PM or email to dgallon@cox.net. (If you want to see all the details of the different camshafts, refer to page 00-0/14 in the BBB or Service Manual.)

[SteveK]

All, thanks for the tips.  The cam I ordered from the classic center is the late US model which should fit my 71 engine.  Great tip on the ball studs.  I think I'll pull the rockers this weekend and test all of the studs so I have time to order some before I do the rebuilt.  (probably labor day weekend)   This site really is great for this type of help!

[wwheeler]

Since some of my ball studs were looser and some were extremely tight, I decided to replace all of them. The Classic Center however only sells the whole assembly including the part that threads into the head. After removing the ball stud, I tried loosening the one in the head and it was very tight even with a 1/2" drive and a breaker bar. I decided to leave that part in the head and just thread in a new ball stud which was good and snug.

Is it OK to use just a new ball stud and not use the entire assembly?

When I removed the rockers, I examined the rocker retaining spring and the spring keeper that mounts on the ball stud. Both had about 20% wear which isn't bad. I checked the prices for these springs and they are less than a dollar each new from the Classic Center. While I have the whole thing disassembled, I replaced all of the spring parts. You wouldn't want one of those failing and for the price, it is cheap insurance.

[Dave Gallon]

1) Besides looseness of the ball studs, it is also important to consider wear to the ball stud and the corresponding hole in the rocker arm. When new, the top of the ball stud is spherical and the corresponding hole in the rocker arm is also spherical. Thus, rotating the ball stud when adjusting valve clearance did not affect the way the rocker arm sits on the ball stud. With wear, the ball stud and rocker arm contact surfaces wear into an egg shaped pattern. That is, the contact surface becomes oval. When the ball stud is rotated (to adjust valve clearance) the rocker arm no longer sits evenly on the ball stud. Obviously some amount of wear in this area is normal and acceptable on a used engine. However, when a rocker arm is removed, do examine the contact surfaces and if they have become oval to the point that valve adjustment will not be reliable, you should consider replacement of both the rocker arm and the ball stud.

2) Obviously, when replacing a ball stud or ball stud assembly, some consideration should be given to the condition of the corresponding hole in the rocker arm. If the hole has an oval wear pattern and you fit it on a nice new spherical ball stud, the life of the ball stud will be shortened.

3) Originally DBAG decided it was acceptable to replace only the ball stud while allowing the corresponding base to continue in service. Some twenty or so years ago that decision was reversed. I do not have any documentation to support what I am going to say, but it was explained to me that DBAG found that as the ball stud bases were getting older, the friction fit between the ball stud and base was inadequate to guaranty reliable valve clearance. Thus, the individual ball studs were no longer supplied. In principle, it is not OK to remove the ball stud from a new base and thread it into an old base. However, practically, those bases can be difficult to remove. If the new ball stud in your old base have a sufficiently tight fit so that the specification is met, it should be OK. The Service Manual states that the torque to turn the ball stud should be 2.0 to 4.0 mkp (about 14.5 foot pounds to 29 foot pounds). So, check the torque and you will know if it is OK or not.

[wwheeler]

Excellent explanation Dave!

I did notice that some of the ball studs had more wear than others and I will check the rocker hole very carefully. As you say, no point putting on new studs if the rocker hole is ovaled and will wear the new ball stud quickly.

I will measure the torque of the new ball studs. I totally agree about replacing both stud and base. I would love to do both but the first couple were extremely tight. I am afraid that if I use a cheater bar to loosen, I might strip the aluminum threads. I don't want to go there!

Any tricks to loosen the bases?

[glenn]

As the miles pile UP, the ball studs wear Down- to 'post' studs.  And the rocker arms conform.  All the more reason to make sure the oil distribution pipe is 'OK'-clean, supplying adequate oil to the bearings, rocker arm surfaces, studs, etc.  Means good oil pressure also. 45 psi?

For a good show   Take the valve cover off, run engine(momentarily),  watch the oil shower.!!!!!!!!  Report back. ..

[wwheeler]

I installed the new balls studs in the old stud bases and read the torque of each. In removing the new studs from the new bases, I found the torque was a much higher value than the given MB range. I measured it on average to be 60 ft. lbs.

Here is what my torque values are for the new ball studs in the old stud bases (ft.-lbs.):
1I - 70, 1E - 55
2I - 60, 2E - 70
3I - 50, 3E - 75
4I - 65, 4E - 65
5I - 70, 5E - 50
6I - 40, 6E - 60

These readings were taken with the ball stud mostly screwed all the way into the old bases. Some readings seem high but close to 60 ft.-lbs that I got with the ball stud assembly. I am very concerned with the 40 ft.-lbs that I got from #6 intake. Should I replace the base on this?

[glenn]

From page 00-3/2 of the 220SEb BBB manual.   'the adjusting torque must be at least 1.5 mkg'    1.5 mkg is about 11 ft-lb.  On a new engine the ball stud is in the furtherest on the offset threads with the highest torque required.  Subsequent adjustments will bring the stud out with less offset thread exposure and less torque required. From the drawing it looks like the stud's upper threads are below the ball pin base by about 2 threads.  2 or 3 mm of wear, i.e., a 2 or 3 mm post instead of a ball -- it's time for new ball studs and rocker arms. 

60 ft-lb seems high for the ball stud with .003 or .007 clearance on the cam.  At least---it's more than 11 ft-lb!

[ja17]

Hello,

This is where experience translates into cost. After years of experience, an experienced  tech can make good judgement on the individual parts.  Mercedes engines have "allowable wear" limits on all of it's moving parts. Of coarse it is best to remove all worn (and every moving part will show some bit of wear) parts and replace them with new. But the fact of the matter is that you will eventually have more in the parts than an entire assembly will cost new from the factory. In other words if you replace all the worn moving parts in an entire engine, part by part you will have spent  two to three times the cost of a new engine !

Once you decide to replace all parts with any signs of wear, you will find that there is no logical place to stop until every moving part is replaced.   Yes it is best to replace the ball stud bases with the ball studs, then yes, installing a new ball stud with a worn rocker makes little sense. Now installing a new rocker arm on a slightly worn cam is an issue, And then those retaining springs have a bit of wear. Now then, the pressure pads on the valve springs always has a wear slot.  While your replacing the cam, that front chain sprocket is worn and the cam bearings are a little sloppy, can't put a used timing chain on that new chain sprocket can you? Now all those other chain sprockets and rails are old and worn.  Finally, someday you add up your reciepts and you have $10,000.00 in your used tired engine  !

My point here is that good judgement can be used so appropriate costs are encountered. Knowing what the wear limits are, what is critical and what is acceptable or will not cause issues is crucial in final outcome and cost. A good understanding of the life expenctency of a particular engine and future plans can play a role in decisions on repairs.

 If cost is not critical, relacement of all worn parts can be the safest but  often the most wasteful procedure.

Experienced eyes can examine and measure parts with some slight but acceptable wear and realize they will last the life of the engine and re-use or recondition them.  Experienced eyes will realize that a particular part will last longer than the rest of the engine.  Experienced eyes will understand that some customers demand and afford different levels of perfection.

Good judgement is the key to controlling costs and longevity of the engine.  I just hate to see everyone run out and buy all those expensive new "good for 200,000 mile" parts  and put them on 50,000 mile engines!

[wwheeler]

Joe, you make an excellent point and I am probably one of the worst culprits of the domino effect you are talking about. It is a balancing act for sure.

I tried replacing the #6 intake base in an effort to bring up the ball stud torque on that valve to match the others. NO LUCK. I am not sure who put these bases on, but they are tight. I had a 1/2" drive 24mm socket and breaker bar with a 30" (no kidding) arm and still could not break it loose. In fact, the 1/2" short extension attached to the socket even started to shear. That's when I said I'm done with that. I then tried to mix the ball studs and took the highest torque one and switched it with the lowest torque. Believe it or not, it actually helped. So now, they are within a 50 to 65 Ft. Lbs. range. That's good enough for me!     

I put some blue indicating fluid on a ball stud to see where the wear pattern would be with the old rocker arm. I could clearly feel the old rocker contacting only the sides of the new ball and the indicating fluid confirmed that. The wear in the cup on the arm does seem significant so I will probably replace those.

As Dave pointed out, as the rocker and ball wear from the back and forth motion, they tend to form an egg shaped pattern. When you rotate the ball stud during valve adjustment, the egg shaped patterns no longer match. I assume that if you don't adjust the valves frequently as recommended, this egg pattern becomes deeper and harder to overcome.   

[Dash808]

Good point Joe.
So basically save yourself the headache and just buy a new motor before the OCD kicks in.  But wait, while the motor is out might as well replace this or work on that or clean up the eng bay or do a little painting...   

[Dave Gallon]

1) Alfred Esser pointed out to me today that the 1959 Service Manual quoted 1.5 MKP. I checked a Technical Data Book from a few years later which provides data for the 230SL and Mercedes revised the number to be 2.0 to 4.0 MKP. This is the number I quoted in my earlier post. I have nothing to prove this assertion but believe Mercedes revised the minimum torque requirement.

2) Joe's comments are, as always, insightful and well considered. Whenever advising another person on how to maintain / repair a car, it is very important to consider the likely life expectancy of the car and the expectations of the owner. Joe has expressed these ideas eloquently. Things would be a bit easier if we could still buy a new engine (long block) or at least a short block from Mercedes.

[Cees Klumper]

At least a few years ago, the parts book still listed a new factory engine for (as I recall) the 280 SL from MB at EUR 17,500, or roughly US$ 23,000 ...

[ja17]

Hello Wallace and Dave,

Infrequent valve adjustments and dirty oil will cause the ball studs to wear into a "crowned" ball which will not give you accurate or lasting valve adjustments because the "crown" does not wear symmetrical.  During a engine rebuild these worn balls are normally replaced.  During a standard adjustment on an older engine, these crowns can be ground off flat and reinstalled and will adjust fine.  

These engines normally wear "loose". So worn parts and loose ball adjusters will normally move downward causing noisy or loose valves. This is much more desirable than engines which wear "tight" causing loss of compression and burnt valves !  Old VW beetle engines and earlier MB engines like the early 190SL had tappets and valve trains which did wear "tight". Burnt valves resulted in infrequent valve adjustments.

I always hesitate to re comend replacing the ball stud bases since, on rare occasions they become stuck and can gaul the threads in the head during removal. Sometimes they must be removed. If removal is required try to do it with the engine hot.  I use a strong air impact gun since the combination of the impact shock helps break the grip of the aluminum on the base. Even with an impact, a long 1/2" breaker bar and   quality socket may be required for the first turn after which I go back to the impact at times switching it to forward then reverse to ease removal.  I do not use an impact tool during reassembly only a torque wrench. The treads must be sealed or you will get some oil seepage into the exhaust manifold or around the spark plugs  (sweating oil around the spark plugs on the outside of the head).

[wwheeler]

I found that some of the ball studs had "normal" wear and some of them had excessive wear. The ones that had excessive were were the ones that had ball studs that were VERY tight. So I don't think these ever got adjusted properly.

Because the bases were so incredibly tight, I didn't want to risk doing as Joe mentioned; striping the aluminum threads. So I kept all the original bases. Interstingly, I found that the torque value is not exclusive to either the base or the stud. In other words, using the existing bases, I was able to switch the ball studs around to achieve a close torque range for all valves.   

[SteveK]

I removed all of my rocker arms this weekend and then put the torque wrench to the ball studs.  I set the wrench on 15 ft-lbs and 6 of the studs would not hold.  All off the studs were ovaled to a degree so I decided to replace them all.  The Classic Center came through again with a reasonable price! 

On a separate subject, one of my corvette buddies gave me an article on recent cam failures in older vettes that is very interesting.   I'll start a new thread to talk about it.

[SteveK]

I'm in the process of putting the head back together.   Have the new cam in, chain on and head bolts re-tourqued.   The write up in the tech manual was good with the exception that it says you do not need to drain your coolant.  Looks like I should have as when I went to turn the motor over with the started (no rockers or plugs) I found out I had water in at least two of the cylinders.  It must have leaked over the night.   (I did have the 6 cover head bolts in and tight, but that was obviously not enough.    I've spun the engine a number of times and the only thing coming out of the plug holes now is an occasional fine mist. 

Besides draining and changing the oil, and adding new coolant, anyone know if I need to do anything else before I crank it up?

[ja17]

Hello Steve,
Watch the temp gauge. These engines will get an air block and overheat until they are "burped".   When the top radiator tank becomes hot, then the coolant is circulating and you are safe for a test drive . 

[SteveK]

Joe, thanks for the tip.  I completed everything, changed all of the fluids and let it heat up burping a few of the lines as it got warm.   I then re-torqued the head, let everything cool down and then re-adjusted the gaps.    I'm surprised at how much smoother and quieter the engine runs.  The only issue is now for the first time I can hear my chain   I guess that will be another project in a few months!

[wwheeler]

Like Steve, I changed my rockers and ball studs but didn't replace the cam. When I first fired up the engine after this work, the valves were quiet with just a bit of tapping. After letting the engine run a while, a little more tapping returned although it is still much better than before. I set the valves exactly at .003 and .007 for the intake and exhaust respectfully.

Since there are a lot of new wear surfaces, when should I go back and check the clearances?