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1989 560SL Pajett Red / Red 66k miles
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20 Posts
Discussion Starter #1
Hi gang,

I have an 89 560sl with less than 70k miles. The mechanic is advising replacing the timing chain tensioner because there is some rattle at start up.

After looking at the rails, mechanic recommends just replacing the tensioner not the rails and timing chain too.

I'm curious as to what your opinions are.

Should I go the whole 9 yards now or wait?

Thanks

Rich
 

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1986 560SL 200,000 km
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58 Posts
Sounds like the tensioner is suspect indeed. Judging by the brown colour of the visible guide rail, you should change the upper guide rails plus the tensioner guide rail. Also the plastic oiler fittings on the oiler tubes above the cams. Your mechanic can check the chain timing marks on the cam sprockets for cam sprocket wear and or chain wear/stretch. With the low milage and if the oil has always been changed regularly, the chain may still be OK.

The guide rails and the oiler tube pieces get darker with age and become brittle which can lead to regretable failures.
 

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Premium Member
1983 380SL, 2000 S430, 1991 420SEL (retired) - RHD
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5,339 Posts
Chain rattle

Hi gang,

I have an 89 560sl with less than 70k miles. The mechanic is advising replacing the timing chain tensioner because there is some rattle at start up.

After looking at the rails, mechanic recommends just replacing the tensioner not the rails and timing chain too.

I'm curious as to what your opinions are.

Should I go the whole 9 yards now or wait?

Thanks

Rich
If it's rattling you have to do something pronto! Downside is major $$$$. Best to use an OEM tensioner asap. That reduces the risk but those guides have to be replaced.
 

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1988 560SL (California Model)
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5,092 Posts
Time to bite the bullet and replace all. It will probably be a "once in a lifetime" job. Strongly suggest you go OEM on everything. You'll sleep better at night...
 

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Premium Member
1987 560SL
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2,349 Posts
Nice clean engine reflecting consistent oil changes and low mileage. Congratulations. As stated by others, replace those guide rails and plastic oil nozzles. These plastic (or composite) parts fail with heat and time, not just chain friction. If your cam sprockets line up simultaneously with the timing marks (bottom of your right picture above) the chain has no stretch and lots of useful life. If there is more than two degrees of stretch consider a new chain plus sprockets. And yes, the aftermarket chain tensioners are inferior to OEM Mercedes, no need to take that risk.
 

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86 560SL
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1,243 Posts
Don’t have that much experience with Mecedes engines, the SL is my first Mercedes. I replaced my guide rails last year @47k miles. Took a hammer to one of them and it shattered into numerous pieces, there was no flexibility left in it. The chain and tensioner were still good.
 

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1986 560SL 200,000 km
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58 Posts
I replaced my guide rails last year @47k miles. Took a hammer to one of them and it shattered into numerous pieces
I did the same thing after replacing mine and it was truly amazing how brittle it was. I was glad I put on safety glasses...
 

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1989 560SL Pajett Red / Red 66k miles
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20 Posts
Discussion Starter #10
Gang,

I had a lot of anxiety regarding what to do about the guide rails. I was willing to spend the money but was advised against it by several different shops.

After speaking with two mechanics, one an ASE certified Mercedes with over 30 yrs experience I have been told that the whole timing chain guide rail issue on a 560SL is overblown. One of the mechanics I spoke with have never seen bad guide rails on a 560SL and has serviced hundreds of these cars.

I saw an old episode of Wheeler Dealers where they did the job on a high mileage example. Maybe that's why the concerns escalated? Not sure.

The 380sl does have the problem but very rarely the 560sl. These are from different shops in So. Fl. who work on the 560sl all the time. They have nothing to gain from me by telling me this. In fact, it's a big job so why wouldn't they want to take my money?

They recommended the tensioner replacement but said that if the guide rails look good leave them alone.

So I had one replace the tensioner on my 66k '89.

Thank you for all of your opinions and guidance.
 

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1983 380SL, ivory/dk brown, 46k miles, dual roller timing chain. 1986 560SL, red/white, 190K mile.
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6,775 Posts
Gang,

I had a lot of anxiety regarding what to do about the guide rails. I was willing to spend the money but was advised against it by several different shops.

After speaking with two mechanics, one an ASE certified Mercedes with over 30 yrs experience I have been told that the whole timing chain guide rail issue on a 560SL is overblown. One of the mechanics I spoke with have never seen bad guide rails on a 560SL and has serviced hundreds of these cars.

I saw an old episode of Wheeler Dealers where they did the job on a high mileage example. Maybe that's why the concerns escalated? Not sure.

The 380sl does have the problem but very rarely the 560sl. These are from different shops in So. Fl. who work on the 560sl all the time. They have nothing to gain from me by telling me this. In fact, it's a big job so why wouldn't they want to take my money?

They recommended the tensioner replacement but said that if the guide rails look good leave them alone.

So I had one replace the tensioner on my 66k '89.

Thank you for all of your opinions and guidance.
I've heard similarly by the restoration shop who sold me my 560SL. Hard to prove the necessity as the intervals are established by the manufacturer. Over on the Land Cruiser forum there are similar pondering if religious adherence to scheduled timing belt replacement is really necessary.
 
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