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#1
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300SD timing chain (Benzmac)
You answered one of my questions yeterday but????
Are you sure the timing chain can be loose with the enging stopped without any chance of it skipping a tooth or 2? I have never seen a loose chain except one that was worn beyond the take up of the chain tensioner.As I said, the cam was off by 2 degrees. Will the chain be tightened when the oil pressure comes up from running the engine. Also, you didn't answer my question about putting in the offset key between the chain and gear to correct cam timing without cutting the timing chain. Thankyou for your help. P. E. Haiges |
#2
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The tensioner check valve should hold tension between running periods, but often doesn't. I would replace any tensioner with over 100k mi that exhibited such slop. (maybe anyone period)
I would never do a cam timing correction based upon your judgment of the line-up of the marks. I have never seen a motor where the marks lined up exactly, after all they are there to allow you to judge the set-up to within one tooth (18 degrees). If you were changing offset keys then you would push back the chain tensioner with a pry bar/screwdriver to make the chain slack. Then take the nut off and gently tap the gear off the shaft. After changing gear, key, or whatever pick the gear and chain back up pulling tight on the drivers side and slide the gear back over the cam turning the cam to line up the key with the gear. You should do this of course with the crank gear on TDC and the cam in the #1 position. I would recommend that anyone doing this for the first time pull the rocker stands and arms off, so that the motor can be turned afterward and the timing verified without the possibility of hitting valves. ------------------ Steve Brotherton Owner 24 bay BSC Bosch Master, ASE master L1 26 years MB technician Last edited by whunter; 02-15-2011 at 01:28 PM. Reason: spelling |
#3
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I,m glad I re-asked the question when Benzmac said a loose chain was normal. The spring is in there to keep chain tight when there is no oil pressure.When I took the chain tensioner out of the cylinder head, I found that the pressure bolt was completly siezed in the housing.
A new chain tensioner is going in as soon as I can get one. I thank you for your help. Not replacing that tensioner could have been disasterous because we know what happens when the chain jumps a tooth: el stopo and el breako cam towers and maybe valve, cam and piston damage. |
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