believehead Posted October 7 Share Posted October 7 I am detecting around 18 degrees of timing chain elongation on my 1973 450SL. Refer to the accompanying photographs. Does it seem like I have measured this accurately? The engine exhibits no discernible timing chain sounds, and there are no witness markings on the cylinder head indicating chain contact. Link to comment Share on other sites More sharing options...
believehead Posted October 7 Author Share Posted October 7 Link to comment Share on other sites More sharing options...
Kix Posted October 7 Share Posted October 7 The right-hand head seems to be loosening, as it never exhibits bite marks; conversely, the left-hand head is often damaged. Link to comment Share on other sites More sharing options...
partexpat Posted October 7 Share Posted October 7 Upon the replacement of my chain at around 140,000 miles, it exhibited biting marks. I recall it being around 10 degrees off at that time. I am uncertain if it was the first or second alteration. If Sbavo's chain is taut, do you believe it is becoming loose? 18 degrees is considerable! Perhaps the replacement was not put correctly? Link to comment Share on other sites More sharing options...
jaybx Posted October 7 Share Posted October 7 It would operate poorly if misaligned by a tooth, barely maintaining functionality and exhibiting little power whatsoever. Link to comment Share on other sites More sharing options...
partexpat Posted October 7 Share Posted October 7 Your measurements seem to be accurate. Aligned cam markings and thereafter verified the location of the pointer at the balancer. 18 degrees is considerable! Did you see my recent discussion on the same topic? This article illustrates the location of my automobile with the same approach. Link to comment Share on other sites More sharing options...
partexpat Posted October 7 Share Posted October 7 I am around 6 degrees from TDC. The chain is comparatively fresh and taut. Your guides, as well as mine, seem satisfactory. If your chain was changed at any time (indicated by a detachable link), it is conceivable that it was put one tooth misaligned. One tooth measures 20 degrees. If it were rectified, you would be near TDC. Offset Woodruff keys for the sprockets allow for an adjustment range of 4 to 10 degrees (FSM 05-215/4). There are individuals here who possess more expertise than I do on this issue (which is not difficult to get!). It is hoped that they will provide their input. Link to comment Share on other sites More sharing options...
believehead Posted October 7 Author Share Posted October 7 I have not previously seen your discussion on the same topic, but I will examine it now. I own no substantial maintenance data for this vehicle, hence it is conceivable that the chain has never been changed. The indicated odometer mileage is around 73,000, however the odometer was functioning intermittently when I purchased the vehicle. The vehicle operates OK, save from the persistent problem with the rich fuel mixture that I am now investigating. It seems to me that the timing chain is not placed one tooth off. What should be the appropriate tension of the chain? I could not detect a detachable master link in the timing chain when rotating the engine for today's valve adjustment. I have only finished the passenger side so far, and I may postpone adjusting the driver side valves and installing a new timing chain and cam sprockets until next weekend. Should I replace just the cam and sprockets, or should I also include the tensioner and tensioner rail? I must revisit the chain replacement discussion in EGv107. I understand that my 1973 aluminum-backed guides should only be changed if they seem damaged. Link to comment Share on other sites More sharing options...
CryptoGuru Posted October 7 Share Posted October 7 I have not yet engaged in any of the measurement protocols you are discussing about this project; but, I have extensively researched many "MB concepts unfamiliar to me," with this being the foremost among them. It is essential to note that harmonic balancers also decay. The rubber allows the degree wheel to shift slightly, resulting in inaccurate readings. Confirm the accuracy of the HB by measuring TDC in both directions using the 'long item' inserted into the spark plug hole, and thereafter calculate the average of the two measurements. It seems to me that 18 degrees would indicate improper functioning, even if it pertains to just one bank. Link to comment Share on other sites More sharing options...
believehead Posted October 7 Author Share Posted October 7 I matched the timing markings on the harmonic balancer with the movement of the cylinder 1 piston with a borescope. Upon viewing many complete spins of the crankshaft, the balancer markings seem to be precise. Link to comment Share on other sites More sharing options...
Kix Posted October 7 Share Posted October 7 I matched the timing markings on the harmonic balancer with the movement of the cylinder 1 piston with a borescope. Upon viewing many complete spins of the crankshaft, the balancer markings seem to be precise. Link to comment Share on other sites More sharing options...
partexpat Posted October 7 Share Posted October 7 I have encountered reports of chains becoming misaligned by that extent. Occasionally, the engine was spun counterclockwise when the chain was slack. Upon changing my chain, the shop failed to replace the tensioner due to ordering the incorrect part. The chain was noticeably slack. I added a new tensioner that resolved the issue. The chain remains taut, making manual deflection difficult. Link to comment Share on other sites More sharing options...
partexpat Posted October 7 Share Posted October 7 Given the absence of records and the significant misalignment of the chain, it is prudent to replace both the chain and sprockets. Reposition it to ensure the two camshafts and the balancer are aligned. They may not if you just insert the new chain while it remains connected to the current one that is 18 degrees misaligned. The metal-backed guide and tensioner rail seem to be in acceptable shape. Identical to mine. What is the rationale for change? The tensioner on this vehicle differs from those on subsequent models. The one I installed is identical to this one: Pelican Parts SLShop seems to be more economical. Subject to delivery expenses. Link to comment Share on other sites More sharing options...
partexpat Posted October 7 Share Posted October 7 https://parts.theslshop.com/mercedes-benz-timing-chain-tensioner-1160501611/ Link to comment Share on other sites More sharing options...
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