R129 SL500 M119 - timing chain rattle at startup - 240k km - is this the chain or just the tensioner

Started by Banksia_Park_Berny, 23-10-2023 04:18 PM. 14 replies. 2,963 views.

23-10-2023 04:18 PM

Banksia_Park_Berny ★ Silver - Unaffiliated

★ Silver

Join Date: Sep 2008
Location: Banksia Park NSW
Posts: 1,847
Club: M.A.L.A.K.A.S.
Car: 1985 W126 380SEL

probably obvious but anyway.

1994 SL500 (R129) on the hoist at a mates shop. 240k km. Cold start rattle for 2 seconds then quiet. Owner is asking is it the chain or just the tensioner.

The M119 (5L V8) has a duplex chain on each bank plus a primary chain, and a single hydraulic tensioner. The chain set itself usually lasts 200k+, but tensioners develop slow oil bleed-down which causes the cold start slap.

At 240k - worth doing chain + tensioner + guides as a set, or just the tensioner and see how it goes

23-10-2023 05:48 PM

Vasilios_Billy

Lifetime Benzer

Join Date: Mar 2008
Location: Campbelltown NSW
Posts: 1,699
Club: M.A.L.A.K.A.S.
Car: 2020 AMG GT C

Berny.. at 240k the M119 duplex chains are usually still ok. guides and tensioner are the worry.

Borescope through oil filler, look at top guide plastic. if intact with polish marks, good. if grooved or flaking, guides need doing, 8-12 hours.

Measure chain stretch by WIS 05-200 timing mark deviation. up to 4 degrees is ok. over 4, chain is stretched.

2 second cold rattle is classic tensioner bleed-down. if it goes quiet and stays quiet, do tensioner only - about $240 plus 90 minutes.

If owner has money and car deserves it, chain + guides + tensioner at 240k is sensible preventative. about $4,800, good for another 150-200k.

25-10-2023 09:18 AM

Banksia_Park_Berny ★ Silver - Unaffiliated

★ Silver

Join Date: Sep 2008
Location: Banksia Park NSW
Posts: 1,847
Club: M.A.L.A.K.A.S.
Car: 1985 W126 380SEL

Owner has gone tensioner only. Borescope inspection of the guides shows light polishing only, no grooving. Vasilios on the money.

Will report back if the rattle comes back.

+ Reply to ThreadPage 1 of 1

All times are GMT+10. The time now is --:--.