I am having a problem on a couple of my M116 engines. The problem centers around the hydraulic compensators. I usually get a ticking noise when I first start the engine. Especially on cold mornings. Stopping and restarting the engine usually cures it but not always. Now the problem had gotten worse to the point that often times after the engine is warmed up the ticking just starts and stops randomly while driving. I can understand things being sticky when its cold but the random stopping and starting thing is a puzzle. I am worried about beating the cam / followers to death.

Engine has 235K miles, steady diet of Mobile 1 oil since 150K changed at 5K miles or less.


What causes this to happen?

Is the compensator pressurized from the oil system?

Does the compensator use the oil overflowing from the cam oiler tubes to "pump up". If so what would cause the compensator to "deflate" once the engine is running?

Do these things wear out or just get sticky?

What is your recommended course of action to solve this problem.

__________________
I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k

Replace them.

I have done that and the problem has gone away. Thanks for the suggestion.

I cannot tell the difference between a bad one and a good one so I was wondering what the actual failure mechanism was. I guess no one really knows. I sure cannot tell from looking at the compensator. I but the bad one in a vise and compressed it and it held pressure quite just like the new one did.

Oh well - probably never really know why.

__________________
I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k

The oil comes up through the cylinder head and reaches the hydraulic unit through a small hole in the threads where they screw in. Over time they seem lose their internal seal. Then when they sit w/o pressure, they "leak down" and clatter until they fill with oil again. Sometimes the seal is not achieved and they clatter when warm. The clatter happens because the element cannot hold the rocker tight enough against the cam.

If you have this problem with new elements, you can try a thicker "hockey puck" to increase the pressure against the cam. Sometimes rocker or cam wear can cause noise as well.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Chuck, thanks so much for the explanation. I have disassembled one and I thought that was the way it worked. Thanks for confirming that. The bad one did not act any different from the new one so I a bit puzzled as to why. But replacing it I have not had any problems for over a week now.

I probably need to check the pucks and most likely replace them with thicker ones. I imagine that the cam is somewhat shorter than it was when it was new. There is a bit of clatter from all of them although not bad at all.

Thanks again.

__________________
I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k

There is a rather involved procedure for deciding which thickness to use, which requires a special tool, which you can get from AST. I am sure you will find more information if you search on "puck."

Herr Fuchs, my guide in such matters, told me that you want to shim at the high point of tolerance on the tool, rather than the mid point, and that has worked well for me.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe