560SEC Major Checks

My two biggest concerns buying this 560SEC was the potential for rust being a UK car, and the condition of the timing chain.   I was pleasantly surprised when I looked underneath the 560SEC and found that it was not a rusty car.

The other common W126 rust area is under the rear windscreen.    This is also an issue in Australian delivered cars as it’s caused by rain.   Rain gets under the rear window seal causing rust.   The first evidence is that the rear windscreen starts delaminating at the corners.

560SEC Rust

As can be seen from the pictures, the rust has started under the screen.   I have seen much much worse in other W126’s.   This will need attending to before it spreads further and becomes an even bigger problem.

560SEC RustSome of the other W126 rust areas include around the boot and spare tyre well, underneath the car, behind the wheels, bottom of front fenders etc.

The other potential issue is the timing chain.   This is something of a design flaw.   As plastic guides age, they become brittle.   Unlike in the M100, the chain tensioner works on oil pressure which means on startup the chain is untensioned.   As the chain stretches, it flops around on startup, breaking one of the now brittle guides.  Part of the guide gets caught in the chain causing pistons to hit valves and the chain to penetrates the cam covers.   Timing chain failure has been the cause of many W116 & M117 equipped cars being scrapped over the years.

M117 GuideAs the guides age they discolour.   As can be seen in the picture this guide has started to discolour although it has not completely gone.    It is obviously in worse shape than when I checked the condition of the guides in my 450SLC.

M117 Timing chain

To check the chain the air cleaner assembly must be removed.   This was a good opportunity to change the filter.   When compared to the new one it was clearly in need of change.

M117 Air Filter

As this is the high compression 560, it has a twin snorkel air cleaner.

560SEC air cleaner

3 comments to 560SEC Major Checks

  • Rob

    I have the rear window rust problem ’87 560SEC – do you know anyone in Sydney who has a clue about fixing it?

    • admin

      Hi Rob,
      I have not yet looked into the job on my 87 560SEC.
      I did have a similar job done on my 77 450SLC about 15 years ago at vehicle color design centre at rydalmere and was happy with the work they did. I understand that business is still there.

      Good luck, please post back if you find somebody good.

  • […] of power and are a delight to drive.   The M117 has an almost bullet proof bottom end, but an Achilles heel in some plastic parts in the engine.  If these parts fail, it is not economically viable to fix […]

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