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1999 500SL, 1988 SEC
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The adjustment is this. Those pucks are different thicknesses and by using a go no go gauge you put in the correct thickness puck. Search for my post on valve job.
 

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1984 500SEL
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129 Posts
The adjustment is this. Those pucks are different thicknesses and by using a go no go gauge you put in the correct thickness puck. Search for my post on valve job.
Holy Crap. I found your post about your adventure with your valve job and puck, rocker, compensator adjustments. Wow. How is your car running since? Have you figured out the go/no go variances you were seeing?

Thanks for pointing me in the direction of that post. I really appreciate it!

Jason
 

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1984 500SEL
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129 Posts
Car is running great. Still working on little things though
That's what these old cars are all about, isn't it? one small thing after another then BLAMMO!! something big, just to keep things interesting.
So, my plan was to replace all the hydraulic compensators on the left (passenger) side to try to get the ticking sound under control. I figured since I have to remove the rocker arms to do it, I might as well set the used one over there in that pile, and grab a new one from this pile to put back in, HOWever, after reading that post, I am wondering if the combination of new compensator, new rocker and old cam will throw off that critical angle enough to require new pucks? Maybe I'll be better off using the existing, original, rockers (If they aren't damaged, of course) and hoping the same pucks in their same places will be the correct sizes? What do you guys think I should do?
I still haven't had a chance to take a close look at the cam lobes, but I think work is slowing down enough I should be able to do that this week. I want to wait as long as I can, just so all the internal bits aren't left exposed any longer than they need to be, and I am expecting all the parts by the end of this next week.

Thanks, again everyone! You guys are my lifeline with this car!

Jason
 

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Premium Member
1999 500SL, 1988 SEC
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1,353 Posts
Ok here is what I would do. First you have to decide if its a cam lobe or not. It its a cam lobe, or worn rocker then its time for a new cam, and if you do that all new rockers. Typically you can't mix old with new and get good results. From what I see, and the pictures are not good, the cam seems serviceable, which tends to lead to a hydrauilic compensator. So you have to find which one it it. If you do the hammer test, or use the stethoscope you should be able to narrow it down. If its a compensator I would just change that one and leave all the other old parts in. That way you avoid fixing the adjustment pucks and doing the measuring. This would be the least expensive option too. I would also make sure you get the right oil

Now as to mine, it runs well but I still have a little lifter noise. I think its inherant in these engines to have some. I expected it to be super quiet like a Ford OHC but its not. American lifters have a lot more valve adjustment and no pucks, unlike the German counterparts. Good luck
 

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1991 560sec. 1991 560sel 1969 280SL
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Very good advise. Even with high mileage on these engines the wear on the pucks is minimal. There's really no need for puck measurements unless the valve seats have been reground.
 

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Outstanding Contributor
350SDL, '17 GLS450, "Grandpa's Roadster" Project Car
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The only reason to change a rocker is if it's badly worn. Chances are, if you find one you're going to find the cam worn too.

Do NOT mix up the rockers and put one back in any spot other than where you found it.

If you replace a compensator, I would recheck the shim. Chances are it will be acceptable, but if it isn't your just bring on more trouble.

There really are no shortcuts if you want it to be right.
 

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1984 500SEL
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129 Posts
Ok here is what I would do. First you have to decide if its a cam lobe or not. It its a cam lobe, or worn rocker then its time for a new cam, and if you do that all new rockers. Typically you can't mix old with new and get good results. From what I see, and the pictures are not good, the cam seems serviceable, which tends to lead to a hydrauilic compensator. So you have to find which one it it. If you do the hammer test, or use the stethoscope you should be able to narrow it down. If its a compensator I would just change that one and leave all the other old parts in. That way you avoid fixing the adjustment pucks and doing the measuring. This would be the least expensive option too. I would also make sure you get the right oil

Now as to mine, it runs well but I still have a little lifter noise. I think its inherant in these engines to have some. I expected it to be super quiet like a Ford OHC but its not. American lifters have a lot more valve adjustment and no pucks, unlike the German counterparts. Good luck
Knocked off work early tonight and tore into this project. Looked at all the lobes on both cams, and found one, in the exact area the noise was coming from that has very noticeable grooves and scratches that can easily be felt with a fingernail going crosswise along the lobe. I have included a picture. It was kinda hard to get a clear, close up pic, but you can see the scratches. I'm pretty sure I need a new cam. Thoughts?

IMG_1438.jpeg

Thanks everyone! I'm pretty sure I'll be asking a ton of questions about installing a cam. I need a drink.

Jason
 

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1984 500SEL
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129 Posts
Very good advise. Even with high mileage on these engines the wear on the pucks is minimal. There's really no need for puck measurements unless the valve seats have been reground.
I think I need a new cam. Do you think the existing pucks with new rockers, compensators and a cam will still give the proper measurement with the go/no go thingy? Should I get a small selection of different sized pucks?

Thanks!

Jason
 

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1984 500SEL
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129 Posts
The only reason to change a rocker is if it's badly worn. Chances are, if you find one you're going to find the cam worn too.

Do NOT mix up the rockers and put one back in any spot other than where you found it.

If you replace a compensator, I would recheck the shim. Chances are it will be acceptable, but if it isn't your just bring on more trouble.

There really are no shortcuts if you want it to be right.
Yes, I don't want to half-ass this project. It's going to be given back to my dad for his 75th, so I've got to make sure it's safe and reliable. I just hope I can get it done in 2 years!
If I need a new cam, do you recommend replacing the rockers too, or only if they're worn?

Thanks!

Jason
 

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1991 560sec. 1991 560sel 1969 280SL
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1,333 Posts
I can only speak to my experience. When I replaced my head gaskets due to a minor oil leak at the rear of the left cylinder head, I had the heads checked and resurfaced. The valve seats were found to be in excellent order. The original valves were lapped and obviously the valve seals were replaced with MB seals. Upon reassembly I found the cams in very good condition but found minimal wear the size of a pinhead on two of the cam followers. I replaced only those two cam follower. The pucks were kept in their original order, none were replaced.
After reassembly I was fortunate to find no problems whatsoever with the running of the engine. There is no ticking from anywhere on the engine.
I would think if one were to replace the cams, cam followers, and compensators/ lifters with new MB parts, the valve trains factory tolerances will be restored. Unless of course there is abnormal wear on the shims. Personally I would just replace all the above and the cam oil feeder pipes, reassemble everything and fire it up, if all sounds good go for a good long test drive.I would expect a smooth and quiet idle. If the idle is noisy or rough I would check the valve clearance first.
 

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Premium Member
1999 500SL, 1988 SEC
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1,353 Posts
I think we are all on the same page. It looks like you need a new cam. I suppose you could try a used one but thats a mix and match roulette. So if you get a new cam I would use new rockers. Using old rockers with a new cam is usually not suggested. If it were me I also would change that one compensator just because. At first go I would use the old pucks just where they are at and see whats up. Those pucks are expensive. You really are not changing the valve stem length like I did so your variability is much less. My guess is the tolerances on mb rockers is very minimal.

now on the flip side, if you don’t drive much a used cam and rockers can work. Changing a cam is not easy.

John, a question I always wanted to ask you is, can you polish these cams like you do a crank or is the hardness just too thin?
 

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1984 500SEL
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I think we are all on the same page. It looks like you need a new cam. I suppose you could try a used one but thats a mix and match roulette. So if you get a new cam I would use new rockers. Using old rockers with a new cam is usually not suggested. If it were me I also would change that one compensator just because. At first go I would use the old pucks just where they are at and see whats up. Those pucks are expensive. You really are not changing the valve stem length like I did so your variability is much less. My guess is the tolerances on mb rockers is very minimal.

now on the flip side, if you don’t drive much a used cam and rockers can work. Changing a cam is not easy.

John, a question I always wanted to ask you is, can you polish these cams like you do a crank or is the hardness just too thin?
As I've already ordered 8 new rockers, I'll just replace them when I install the new cam. I have a ton of questions about that process, so I'll spend some time perusing the forum to see what knowledge I can gather, but will probably end up starting yet another thread about it. Any advice for getting the cam lined up properly with the timing chain so all the internal bits open and close when they are supposed to?

Thanks for your help!

Jason
 
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