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1976 450 slc
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copper crush washers under the valve cover bolts, plastic cam oiler tube fittings and checking your valve clearances would also be a good idea while your at it...

the lurker
 

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Outstanding Contributor
450slc5.0cab 280sl5sp 280se4.5 500seAMG +250seStkW108 350sl4spdX3 500secEuro
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Discussion Starter #22
Between 11 and 17 degrees of chain stretch

I see why you have to measure several times. It seems like the engine moves more smoothly if you keep it moving. It's not easy to move it just a few degrees with a 10" ratchet (or breaker bar).

It's definitely easier to use your left hand to pull up (while holding the corner of the ratchet/extension down with the right) as opposed to pushing your right hand down into the AC and power steering pulleys and belts with every turn. I only took a few layers of skin off of one knuckle before I learned this. No damage done.

- removed four bolts on fan clutch
- removed four bolts on fan shroud
- Since fan shroud was cracked was able to remove both fan and shroud together without disconnecting any radiator hoses
removed right/passenger valve cover (easy)
- removed hose from brake booster
- removed coolant hose to blower box
- finally removed entire driver/left valve cover (Lots of grease on it. So I guess I'll add valve cover seals to the list and clean the valve covers while they are off.)
- noticed some minor chain slap on driver side, just see clean metal where it looks like all the cooked on oil has been scratched off

Spin #1: 10 degrees ATDC when trailing cam shaft had several degrees to go

Spin #2: 17 degrees ATDC when trailing (right) cam shaft was just a hair past the mark

Spin#3: 11 degrees ATDC when I had them nearly perfectly aligned, and if anything another hair of a degree to go before the trailing cam shaft was perfectly aligned.

That was enough to see that the chain definitely needs replacement... and the odometer on my nearly 40 year old car reads less than 70k miles. I guess that's the lesson to be learned. Never assume the chain is going to be ok due to mileage.

Heck, for all I know, this motor isn't even original to the car.

Pictures:
1) Driver side chain slap damage
2) Turn #2
3) Turn #2
4) Turn #3
5) Turn #3
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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Why replace guides unless they are really worn?
 

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1972 350sl (European)
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370 Posts
I think I'll make this the next maintenance/repair item. I have no way of knowing how long it's been since this was last replaced, but for the price and relative ease of replacing it I'd be a fool not to. I know the guides are the original metal ones, and there aren't any slap marks, so I should be good to go.
 

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Outstanding Contributor
450slc5.0cab 280sl5sp 280se4.5 500seAMG +250seStkW108 350sl4spdX3 500secEuro
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Discussion Starter #26
I hadn't opened mine up before, but I'm assuming that the Jingle Bells sound I heard while I had the babysitter revving the engine at 3000 rpm while trying to set the timing was probably when the majority of this damage occurred.

I definitely agree that this is a must-do for any car that has no maintenance records... At least check for chain stretch.
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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Fonzi, Fonzi, Fonzi.
What are we going to do with you. You don't know if it is the original engine? All you have to do is email the Classic Center with proof of ownership and they will send you the data. Then you find the engine number and see if it matches.
 

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450slc5.0cab 280sl5sp 280se4.5 500seAMG +250seStkW108 350sl4spdX3 500secEuro
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Discussion Starter #29
Fonzi, Fonzi, Fonzi.
What are we going to do with you. You don't know if it is the original engine? All you have to do is email the Classic Center with proof of ownership and they will send you the data. Then you find the engine number and see if it matches.
I've got the data card. I know I've been told where to look for the engine number, but can't remember. I guess I'll look it up before I head out to the garage again.
 

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Discussion Starter #30

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Discussion Starter #32


I was able to verify the first 13 of 14 characters. I think it's probably original. Some time when I feel like looking again, I'll verify that last digit, but I'm confident I've got the original engine now.

Good to know the person who sold me the car saying it was the original engine was correct.

So that settles it. 39 years and 70,000 miles can put 11+ degrees of stretch on a timing chain. (No surprise to you guys who know what you are doing I'm sure.)
 

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1972 350sl (European)
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The Clap - Russell Brand (Infant Sorrow) - YouTube


I was able to verify the first 13 of 14 characters. I think it's probably original. Some time when I feel like looking again, I'll verify that last digit, but I'm confident I've got the original engine now.

Good to know the person who sold me the car saying it was the original engine was correct.

So that settles it. 39 years and 70,000 miles can put 11+ degrees of stretch on a timing chain. (No surprise to you guys who know what you are doing I'm sure.)
I'm almost afraid to see what 39 years and 112,000 mikes has done to mine!:eek:
 

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1972 350SL 148,000 miles
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7,044 Posts
I'm almost afraid to see what 39 years and 112,000 mikes has done to mine!:eek:
or 40 years and 150k miles has done to mine, I'm not even going to measure the fucking thing, just replace it, deal with the associated maintenance when I can afford it, I have a chain tool I can rotate my engine with without removing anything since I have no AC, just pull the valve cover and spin a new chain on using 3 sets of vice grips and the chain tool
 

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Discussion Starter #35
If you can spin the engine, it is very easy to measure the stretch. Since Procto's car had some good maintenance in the past, I would assume the chain has been chainged in the past.

To get the full value of the chain replacement, I'm pretty confident that the sprockets and chain tensioner should be replaced at the same time.

I'm wondering if I've come this deep (injectors, valve covers, chain, valve measurements,etc) if I should just pull the intake manifold and get it all cleaned up while I'm at it. (I'm definitely planning on cleaning and maybe even polishing up the valve covers & fan.)

Since I'm digging myself deeper and deeper into this, I see the logic in quickly pulling the passenger valve cover and just getting the chain replaced.That's less than $100 instead of about $300 too. Hmmm... (Insert corner cutting thoughts here.)
 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
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So that settles it. 39 years and 70,000 miles can put 11+ degrees of stretch on a timing chain. (No surprise to you guys who know what you are doing I'm sure.)
So after doubting the origines of the engine....you still think you have the accurate declared mileage on your SL. A cluster is much easier to fiddle with than an engine change.
Hmm?
 

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Discussion Starter #37
Good point Nobby (on a possible cluster change). But there are two things that made me figure it could be possible that the engine was changed:
1) with the color change from white to black, and the entire engine compartment being well painted, and the heavy accident damage, I think there's a high probability that the engine has been out of the car.
2) That's a lot of chain wear for less than 70k miles, and my mechanic said he thought the wear on the car is very consistent with a 68k mile car.
Additionally, I wasn't able to lossen the steering wheel nut, and assume it has the original locktight still on there. However, this means nothing since it's possible that stronger locktight was used, and that's why I wasn't able to loosen the nut.

I'm sure chain stretch isn't purely based on miles. I wonder how many thousands of miles of chain stretch I've caused in the last few miles while messing with the timing. I'm sure it was already stretched as I've always heard more clatter on that passenger side. All things learned by a novice. Thanks for teaching me everyone!
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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Ahh... this is why I didn't bother looking at it... http://www.benzworld.org/forums/r-c107-sl-slc-class/1437239-where-engine-number-starter-76-450sl.html#post3415780 I've got one of those mirrors on an antenna stick. Hopefully that will help.
You should be able to read it with out the mirror.
A good investment is a gun cleaning. Different size brushes can be used to clean hard to reach places and also parts. A small brush can be used to clean the inside of the cam oiler tubes.
 

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450slc5.0cab 280sl5sp 280se4.5 500seAMG +250seStkW108 350sl4spdX3 500secEuro
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Discussion Starter #40
Thanks! I haven't ordered my chain yet. So I've got some time to research this topic, and learn how the valves, lifters, oiler tubes, etc all work.

I'm assuming a "gun cleaning" is the same thing as a gun cleaner. I will look that up, and hopefully keep learning.

THANKS!



You should be able to read it with out the mirror.
A good investment is a gun cleaning. Different size brushes can be used to clean hard to reach places and also parts. A small brush can be used to clean the inside of the cam oiler tubes.
 
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