91 560 SEL - 115k

Well I have gone this far into the motor so why not do the timing chain, Right? It all started with no heat, so a good place to start was with the thermostat. That turned into a water pump removal since I broke a bolt in the top of the darned thing and tried drilling and using an Easy Out with no luck. Now with most of the front of the engine apart should I go for the chain or just the guide rails? I,m driving the 944S so I can take my time. I have AllData and the factory CD manual but it will not open now so its useless. Anyone else have problems with the CD manual? Does the front cover use a gasket or just sealant?

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Gerry

59 Ranchero
83 928 Euro S
84 928 Euro S
87 300D Turbo-Frybrid "WVO, Tastes Great - Less Filling"
90 750 IL
91 560 SEL

Why don't you pull one of the valve covers off, line up to cam marks, and read the chain stretch of the timing marks? No sense in doing a chain if it's not needed. You really need to read the section on the front cover to decide if you want to get into it. You need to pull the oil pump and a bunch of other stuff.

The gasket kit comes with a gasket for the cover but most people seem to use RTV sealant.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Chuck: Where is the section on the front cover? Do you mean search the archives under front cover or is there some write ups on the subject? I think I am going to replace the guide rails at least and when I pull the front cover I will check the chain for stretch.

Can you or anyone else elaborate on how to tell if a chain is stretched beyond hope. Its only got 115K. I read on the board that a chain should go for at least 200K as long as the guide rails are changed every 100K. Do I line em up at TDC and see if there is any 'play' in the chain?

Today I removed almost every thing but the alternator and air pump for the front cover removal. I might as well replace the two suspension pump hoses while I'm in there. I have to do all this to get at the guides anyway right. The harmonic balancer and pulleys came off OK. One thing I dicovered is that my Porsche 928 Flywheel Lock tool works perfectly on the Big Benz motor on the drivers side. Just remove the small cover and bolt it in using some spare bolts lying around. No need to even remove the starter to lock the engine when removing the crank bolt.

__________________
Gerry

59 Ranchero
83 928 Euro S
84 928 Euro S
87 300D Turbo-Frybrid "WVO, Tastes Great - Less Filling"
90 750 IL
91 560 SEL

I meant the section on the CD, since you mentioned that you had one.

You don't need to pull the cover off to check for stretch or to change the chain.

If you send me an email, I will send you the sections off the CD if you still can't read them.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

once you find out how to check for stretch, 7 degrees is the max. at 115k, i'd be suprised if it was less. seen chains break at 100k, replaced alot between there and 120k. good luck, chuck.

300SDLLL - The reason I suspected the thermostat was the engine temp would not go above 55-60 degrees and with a piece of cardboard in front of the radiator it rose a little bit, maybe 65-70 so it sure seemed that the thing was stuck open to me. Outside air temp in the teens (COLD)

Porkface - How does one find out how to check for Chain Stretch? Also do you measure the 7 degree max limit on the cam or the balancer?

If I just replace the upper guide rails, can it be done without yanking the front cover? Thanks guys, I learning fast.

__________________
Gerry

59 Ranchero
83 928 Euro S
84 928 Euro S
87 300D Turbo-Frybrid "WVO, Tastes Great - Less Filling"
90 750 IL
91 560 SEL

I personally don't believe that the line up markings are distinct enough to judge chain stretch. The proper way to do it is with a dial indicator on the proper valve. At 2mm of lift there are specifications for crank position. The crank markings are distinct and thus are the measure.

The upper rails do not need the cover to be removed but everything mounted to the front must be removed to expose the rail pins.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Even if there was no stretch on the chain you should replace it as long as you have the engine apart. Also, the guide rails have plastic that ages and becomes brittle after 10 years and this plastic can break and get into the chain and timing gear teeth and cause major problems. Best to replace everything now.

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1986 560 SEL (159K miles)

That does it! I'm ordering the chain and rails today. Might as well be safe than sorry, anyway I'm just dying to see what condition those rails are in so I'm going in! Its pretty tough to warm up the garage when it hit 6 degrees out like last night, but I have a nice wood stove in there and it helps bring the temp up to around 40.

To get the original chain off, do I grind a link out and snake the new one in? Does it matter with the cover off as long as your at TDC. I guess there is no need to "snake" it in (rotating the engine) just put the chain on and secure the master link.

If the crank is at TDC, should the cam marks be precisely on target? Thanks guys, I have to go chop some more fire wood!

__________________
Gerry

59 Ranchero
83 928 Euro S
84 928 Euro S
87 300D Turbo-Frybrid "WVO, Tastes Great - Less Filling"
90 750 IL
91 560 SEL