Timing Chain Tensioner?

Tiny
DD849A
  • MEMBER
  • 2006 MERCEDES BENZ E350
  • 3.5L
  • V6
  • 2WD
  • AUTOMATIC
  • 126,000 MILES
This M272 engine (#30-061884) uses the older style 2 piece timing chain tensioner. The style with an end cap. Due to occasional hot start timing chain rattle, I want to replace the tensioner. Are there any special installation requirements like crank position etc. As with the newer style tensioner (crank at 40 degrees)? The WIS isn't clear about this. There are no codes or check engine light. Thank you.
Friday, September 26th, 2025 AT 5:55 AM

7 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
If you are not replacing the timing chain you are okay and don't need to worry about the timing marks. The 40 degrees is for timing chain replacement only. Make sure not to turn he engine over when doing the job. Are you replacing the guide as well? Do you have the timing chain cover off? Check out the images (below). Let us know how it goes.
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Friday, September 26th, 2025 AT 11:05 AM
Tiny
DD849A
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Thank you Ken! Replacing only the tensioner. Minimally invasive job. Timing cover is in place. Not replacing any guides or chain. The purpose is to try and fix an occasional hot start chain rattle. Cold starts are normal which is the reverse of the typical M272 rattle symptoms. Unknow if the balance shaft was ever replaced. Looking into the oil filler hole; it is clean with sprocket, gear and chain like new. No codes or drivability problems on this 126K mile vehicle.
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Saturday, September 27th, 2025 AT 6:55 AM
Tiny
KEN L
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Sounds good, replace the tensioner with the updated model it should fix the problem. Let me know how it goes and if that fixes it.
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Saturday, September 27th, 2025 AT 11:20 AM
Tiny
DD849A
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Supplemental question: Ken, you mean the old and new style tensioners are interchangeable? I ordered an old style MB 2 piece tensioner because FPCEuro said it was correct. Photo looking in the M272 oil fill hole. Rather clean?
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Saturday, September 27th, 2025 AT 2:01 PM
Tiny
KEN L
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That is clean, nice engine. I guess it is the regular tensioner, I don't know where I got updated, sorry. Check out the images (below).
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Saturday, September 27th, 2025 AT 9:12 PM
Tiny
DD849A
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Thanks again Mr. Ken. The MB tensioner is back ordered so it may be awhile before the install and final report. Once the new tensioner is installed, I will remove the spark plugs to make it easier to turn the crank over by hand to be sure all is well.
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Sunday, September 28th, 2025 AT 6:08 AM
Tiny
KEN L
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Good call, this should help the problem, you may have a broken tensioner spring which will cause the issue you have described.
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Sunday, September 28th, 2025 AT 10:59 AM

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