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1977 450SL
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Discussion Starter #1
I'm in the process of adjusting the preload on the hydraulic compensators on my 1977 450sl (a real treat to drive). What and absolute PITA. I'm sure it is solid once done, but getting there is a real journey. Any one devise a method of pressurizing the oil system to avoid having to keep cranking it before taking a measurement? I bought a tester that looks correct for this engine, but it does not match any numbers I've seen on the Forum. I have a stamped 9175890623 tool. Ring a bell of anyone? Perhaps a later tool code change? If not for the 450sl, what engine is it used for? Perhaps someone would have a better use for it. This car is teaching me a LOT of things I obviously missed growing up...and that's been awhile. Wife says I never have grown up. Thanks for your input.
 

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1979 450SL UK spec
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1,604 Posts
This is the only refernce I could find to that number.

2651023


When I have checked mine I didn't just turned the engine over at the crank between each measurement.
 

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1977 450SL
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2 Posts
Discussion Starter #3
Thanks for the information. Seems like I have an original. So you just turn the cam to the heel of the lobe, check and go down the line? I don't have the procedure with me right now, but I recall the shop manual saying to spin the motor over for 30 seconds to pressurize the compensator before taking the measurement. You know what kind of mess that makes. I would think the strong internal spring would be sufficient to take up any slack keeping it at designed spec. With a conventional pushrod engine, it isn't required when setting up the lifter preload. We're essentially doing the same thing here I would think. What started the whole journey....I changed out the timing chain and replaced the guides as well as the the tightener. It started fine and ran for a little while, but after short rev a loud rapping sound seemed to come out of the cover on the right bank. Scared the crap out of me as it sounded like a rod let loose. I turned the motor off did some general checking around and started it up again. The rapping sound was replaced by a ticking sound now. I had read on the Forum that a failed hydraulic compensator could make that kind of loud sound. I replace all of the compensators on the right side and have been trying to eliminate the noise ever since and trying to get the process right. Thanks.
 

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1979 450SL UK spec
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1,604 Posts
When the lobe is up, there should still be pressure on the rocker arm have a feel and see if any are loose/rattling.
 
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