M130 timing chain slap.

[LJJ]

I have a good running 280S M130 engine, which has had the timing chain and tensioner replaced. The original timing tensioner was replaced when it did not! With the old chain the timing marks showed 5 - 6 degrees retarded, and with the new chain, spot on to maybe 0.5 degrees retarded. The engine runs great, however it still displays a tendency to slap when hot and on the over run (braking). The new tensioner appears to be bleed and firm, no slack chain over the cam wheel. What am I missing????

Thanks

[John Green]

When you say that you can here it on overrun, I am presuming this is while driving? Must be very loud. Have you considered that it is something else? Bad piston slap can be worse on overrun and at idle.

[LJJ]

Thanks for the reply John, no noises at idle when hot or cold. No noises when cold in all driving conditions. Once hot (normal operating temp) you hear a "chink chink" noise when decelerating, braking and turning right, and a more consistent rattle at higher rpm's prior to the auto changing up a gear (3rd to 4th). When hot and you rev the engine and snap the throttle closed quickly, you can hear the chink from the front of the engine area (it does not display this when cold).

Other work I have done-

Replaced spark plugs which were to be found one heat range hotter (NGK5 to NGK6).

Ensured use of 98 octane fuel. This solved a running on issue.

Replaced the timing chain tensioner when the piston was stuck in, and used the opportunity to replace the chain. I did have an issue where the replacement tensioner was faulty and would not bleed.

Given that I had a timing chain issue, I assume this is also?

Thanks

[Bartman4800]

Have you had a look at the chain guides? If they were never replaced, they are probably very brittle and could be worn too...
And an NGK 6 is colder than a 5. If you put them side by side, you see the 6's nose protrudes less than the 5.

The hotter plug (the 5) helps with burning off carbon.

Not sure what you mean with "bleeding" the tensioner. Once there is oil inside, it should be very hard to squeeze it out (due to tight tolerances)

[LJJ]

Yes, 5 is hotter than a 6. It now has 6's.
Guides look okay for what you can see, but hard to determine what the lower ones are like. Nothing obvious at the least.
The tensioners need to be bled on initial install to get the oil inside. Thats why there is the oil pool in the head.