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CLA250 Timing Marks

This is a discussion on CLA250 Timing Marks within the Mercedes-Benz CLA 250 forums, part of the Mercedes-Benz CLA Model Specific Forums category; I am rebuilding the engine of 2016 CLA250. I am surprised to learn that this engine does not have an apparent timing marks in reference ...

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Thread: CLA250 Timing Marks

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    CLA250 Timing Marks

    I am rebuilding the engine of 2016 CLA250. I am surprised to learn that this engine does not have an apparent timing marks in reference to the camshaft and the head and in reference to sprockets (adjusters) with each other. There is no marks at all at the head. I wonder if any of our members has knowledge as how to time the cam with no marks, or if any have a timing marks schematics. The dealer is no help as well as startek website. There is no literature available and that leave us (DYI) stranded. I would appreciate any assistance. I am interested to know the position of the cylinder No 1 cam lobes (intake and exhaust) position when the engine is at the TDC position. Thank you.

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    jmc
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    https://youtu.be/lVUarrYSvPY

    there is an early segment about aligning a mark on the crank pulley
    then there is a later segment after the cam sprockets are removed - there is a pointer and a flat on the cams facing up

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    Thank you JMC for your reply. I watched that video several times and it does not show a clear timing. The cam does have an arrow and the sprockets have several marks at different locations. One of these marks has 3 lines in vertical position and 3 dots beside them. The sprocket also have a mark in horizontal position. So, it is not clear if the arrow should align with what mark. Another thing, the video shows that that arrow is up (12 o'clock) for the intake cam, but it is down (6 o'clock) for the exhaust cam. This situation puts the lobes of the intake cam at 10 O'clock and the exhaust lobe at 3 o'clock. I am not sure if this make sense? all these setting are at TDC. I would appreciate if you have an explanation. They do not make Mercedes the way they used to.

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    jmc
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    I aint gonna guess at where the cam lobes are gonna be, what with the vvt system etc. But at tdc hopefully something is static, like where the cam mark arrow and cam mark divot need to be ... dug around and found something for the M270 timing marks ... seems like both need to be at 12 oclock:

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    Thank you for the valuable info about the position of the both cams. I wonder if you have the position of the sprockets and how they align with the cams. The sprockets have multiple of marks and it is puzzling to me as which mark aligns with what. Would it be possible to send me the source of this diagram so I can dig up more info. Thanks again this is valuable info.

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    jmc
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    I have not yanked off the cam gears yet so cant comment on those markings ... but so as long as the camshaft and crank positions are locked and if the sprockets rotate/mount in a periodic fashion then who knows why all those marks?
    Thats all I could find ...
    European delivery 20140331

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    There are 2 possibilities for sprocket alignment

    Thank you JMC for your comments, I am please to see someone mechanically inclined like you in the form. I detached both sprockets (adjusters) from the cam and discovered that they were designed different from any Mercedes I have seen. Generally speaking, in older Mercedes the sprocket slides over a key (woodroof key), and in newer Mercedes like in 350 engines, the adjuster has a pin that goes into a hole in the cam. In both cases, the alignment of the sprocket and the cam is set correctly. This is not the case in CLA250, (engine 270), the sprocket has no physical connections to the cam. So, if the central bolt get loose, the sprocket will be detached from the cam, and a serious damage to the engine occur. So, how one would align the sprocket with the cam. After examining and searching for the marks, the cam has a small arrow looking at both cams. The arrow in the intake has to be at 12 o’clock, and the arrow on the exhaust has to be at the 6 O’clock, this will set the cams correctly. However, the sprockets (both inlet and exhaust) has several marks. There is one mark at the back base of the sprocket which is very light and hard to see. Photo1 shows the arrow on the cam (has black sharpie color) can be aligned with the base mark. However, the sprocket rear wall has 3 vertical lines and 3 dots beside the lines. Photo 2 shows a second possibility of aligning the small arrow to these 3 lines or dots. So, it is a puzzle, which one of these alignments is the correct one, photo 1 or photo2. Can anyone solve this puzzle? Thank you.
    Note: I drew arrows using black sharpie for clarity.
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    jmc
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    The singular arrow related mark seems like a reference point
    My wild guess is the triplets seem like nominal and limit marks? Correlates somewhat to the mechanical tongueingroove thingie which is sandwiched between the sprocket and flange
    European delivery 20140331

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    The CLA250 timing marks reported by JMC are the correct ones. I am pleased to report that after rebuilding the engine and set the time as reported, the car ran beautifully. It was a successful project, yet it is time consuming.

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    jmc
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    Quote Originally Posted by zalsaigh View Post
    The CLA250 timing marks reported by JMC are the correct ones. I am pleased to report that after rebuilding the engine and set the time as reported, the car ran beautifully. It was a successful project, yet it is time consuming.
    Oh thank goodness!
    Maybe one of these days you can post a collage of your rebuild ... at least a couple folks would be happy to see that
    European delivery 20140331

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