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Discussion Starter #1
Hi Guys,

So I recently acquired a 450SL that had been dormant for about 6-12 months, ran real bad but the more I started it up and drove it the better it got, adjusted the CO a little and kept driving it until it has really smoothed out now. I've only driven it short distances replaced fuel filter and spark plugs. I still need to change the oil even though it looks golden "good" but must be old and lost properties by now.

Thing is... two times already at start up it has given me this awful rattling sound like oil starvation, but it goes away so quickly that it doesn't even give me time to react. The engine sounds perfectly smooth afterwards no slapping no nothing.

Now I've read about timing chain failures in 380SL's would this be a warning sign? And is this 77" also prone to failures like that? When I get cars with timing belts I am very wary but I've never had to worry much about chains before.

I'm wondering if I can change the oil first and see if that was the reason, or should I just take apart everything?

The final question is, will turning the engine with no coil until pressure rises, then connecting the coil and firing it up, prevent chaos? I ask this in case I have to tear it apart because if it's too expensive, it might have to wait a little bit and I don't think it will be good to leave the car sitting for long.

Any feedback is appreciated.
 

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R/C107 Moderator
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Yes. Your engine can have timing chain system failure. All the 107 V/8s do. Sounds like you are hearing timing chain slap. Some times due to failing tensioner, chain stretch, or broken upper guide.
 

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Discussion Starter #3 (Edited)
Yes. Your engine can have timing chain system failure. All the 107 V/8s do. Sounds like you are hearing timing chain slap. Some times due to failing tensioner, chain stretch, or broken upper guide.
Well that sounds unfortunate though not as unfortunate as a destroyed engine.

Would you replace the oil first with a new correct one (might have a heavier oil or lighter oil who knows) before tearing the thing apart or is it that risky that I have to stop everything and just open up the valve covers and look for sag and broken guides?

BTW: It has only done this twice and when cold.
 

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Pull the valve covers. Look for chain slapping marks on the head. Measure chain stretch and look at the guides for obvious break. This is covered in the EGv107 Sticky at the top of the main forum page.
 

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Discussion Starter #5
Pull the valve covers. Look for chain slapping marks on the head. Measure chain stretch and look at the guides for obvious break. This is covered in the EGv107 Sticky at the top of the main forum page.
Will do thanks a lot, better safe than sorry. Will post back with what I find!
 

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Discussion Starter #6
So, took apart the valve covers which I was hoping I didn't have to but to my surprise the engine looks very clean the guides look old but in one piece and solid. The chain doesn't feel like it has any slack. Here are some pictures and a video link to you tube.
 

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Looks good to me. But while you have the covers off, you should check the chain stretch. More info in EGv107, but basically set passenger side cam on mark, then check where pointer is on crankshaft balancer. Doesn't have to be exactly at TDC, but at least within 5deg? The stampings on balancer can be a bit confusing!
 

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Guides need to b changed. Read the EGv link Graham posted.
 

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I agree with Rowdie- the guides are brown and s/be changed. They get brittle with age and the color is an indication. Maybe the rattle is because of a failing chain tensioner?
 

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FWIW..About a year after I bought my '79..(84K miles), I started it one morning and heard the "death Rattle". Shut it off..winched it on trailer..and took it to shop. Guide had broken in half, and was hanging by a tiny piece..Replaced chain, guides, oilers, etc.. Good insurance if you are going to drive the car regularly..
 

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Thinking away from the Timing Chain being the noise ... if the noise happens more so when you rev the engine then it might be an Engine Mount or Engine Shock causing the fan blade to rub against the radiator shroud.
 

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It Is What It Is, Dude
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I see no signs of chain scoring on the head casting though it's hard to be sure in those pics. If there is in fact no scoring I'd suggest the start up rattle may well be several of the hydraulic compensators leaking down.
 

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Discussion Starter #14
Had to put it back together because we are doing some work in the house and the car had to be moved, but... I disconnected the coil wire and turned it until it had oil pressure and it took quite a while of turning the engine. Had to do it twice wonder if something is wrong in the oil filter side or tensioner and getting the system depressurized too quickly.
 

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Discussion Starter #15
Thinking away from the Timing Chain being the noise ... if the noise happens more so when you rev the engine then it might be an Engine Mount or Engine Shock causing the fan blade to rub against the radiator shroud.
It's a second tops so there's not even time nor do I rev the car when starting. Basically turn the key, rattled for a second and went away before I could even start to realize what was going on! It's 100% quiet once it goes away at idle and while revving. The fan clutch does make an awful lot of noise though! :laugh
 
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