Chain Slap vs Valve Noise?

The engine of my 1982 380sl with app. 180K mile on it recently started running rough and making a rattling, sometimes clanking, sound when it's cold; in fact, the colder it is, the noisier it is. However, the
noise always goes away after a few seconds, once the engine is running smoothly, and the engine runs great otherwise -- except that it smokes until it reaches operating temp, probably due to worn valve stem guides?
I replaced the valve stem guides myself at about 100k miles, along with the upper chain guides, tensioner and chain, though the engine wasn't making any noise at that time.
My questions are:
1) Is there a way to tell the difference betweeen "chain slap" and noisy valve lifters, since -- AFAIK -- both usually go away after the engine is running smoothly?
2) Since I don't have a garage anymore, does it make sense for me to have a mechanic check for chain stretch, or should I just have him replace the chain, given the cost of checking it and the car's mileage ?
2a) If so, should I get the chain directly from MB, or is an aftermarket brand, like the IWiS from the Benzbin, just as good?
3) When he checks or replaces the chain, is there a way to check whether the chain guides and/or tensioner need to be replaced, too, or should I just have him go ahead and do that to?
4) I heard somewhere that the lower guides rarely break, but should be replaced at app. 200k miles anyway, Is that really necessary, given the cost this would add to the jobl?
5) Finally, when I was under the car a few days ago, and a friend started it up, I heard a whirring sound that seemed to be coming from the oil pump until the engine warmed up. As it sounded similar to the one my old fuel pump made before I replaced it, I was wondering if my oil pump could be going too. I'd hate to think that it was, since I understand that getting to it requires dropping the undercarriage. Does anybody happen to know what the typical life of the oil pump on a 107 is, and what, if any, symptoms, a failing one demonstrates?
Thanks very much in advance for any help anyone can give me answering any of these questions -- especially Karl , Tiger and the other experts.
Best wishes to all for a happy, healthy, prosperous and MB- problem-free New Year,
Bill
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Bill:
I'm no expert but I have a 380SE (W126) and here is my humble suggestions based on my (limited) experience. First, I would not drive this car until the cause of the noise is identified: a broken chain is no fun (this is where my personal experience comes in :-( )

The car has hydraulic valve lifters and I don't think they will make any noise. The chain tensioner may fail however (personal experience again) and let the chain slap. This will certainly kill the engine if you continue running it: the chain will destroy the chain guides and eventually jump some teeths on the cam sprocket and -as somebody else has framed it- then expensive things starts to happen.

What _I_ would do first (as it cost no money and can be done quite easily) is to let the car stand overnight to cool off. Turn the engine over to the TDC mark, remove the right hand (passenger side) valve cover and have a good look: Does the mark on the cam chain sprocked match? (You may have to turn the engine one complete turn, though.) Does the valve guides look intact? Any sign of small plastic pices (remants of destroyed valve guides) anywhere? Does the chain feel loose? Take a wooden stick and try compressing the chain tensioner (from the inside: press the chain out towards the tensioner): it should resist.

A failing one would certainly give low oil pressure. On my W126 one can get at the oil pump by removing the small oil pan, but I believe the 107 models use a different pan, so it may be more work.
Good luck.
pej
--
Per Erik Jorde

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The OP stated that he was considering ordering parts for TheBenzBin.com. I recommend staying away from this company.
I placed an order with them in July for a muffler and header pipe and it was my worst internet buying experience ever. No email confirmation, took almost 2 months to ship the muffler, which came unboxed and all dented and mangled. Oh, and they charged my credit card at the time the order was placed. Despite repeated phone calls over 2 months, I could never get an answer as to the status of the header pipe. No returned phone calls either. Finally, calling them again in early Sept, they told me "Sir, the header pipe order was cancelled last week and your money refunded." And how was I supposed to know this?
So, then I place the order for the header pipe with Carstuff.com over the phone. The guy I spoke with looks up the part, assures me they have it and can supply it. I even told him my experience with TheBenzBin and asked if he ever heard of them. Answer: no
Well, a few days later, I go log back on to thebenzbin website to check my return status and guess what? Incredibilly, it now shows a new order, which is the one I placed over the phone with Carstuff. So, clearly these 2 companies are linked.
So, now I get on the phone and call up Carstuff and read them the riot act. Telling them I just went through 2 months of screwing around with thebenzbin and now it looks like I've placed the same order all over again with the same company for a part they can't supply. Carstuff admitted they they did in fact have a business relationship with thebenzbin and a shared order system. He assures me the muffler has already shipped and the header pipe is sitting in the warehouse right next to his building. I ask for tracking # for the muffler and he says he will email it. No email ever comes. Both of these turn out to be lies. The muffler did not ship until days later. They never had the header pipe and finally refunded my money.
The guy at Carstuff told me to email pics for the RMA of the muffler from thebenzbin to snipped-for-privacy@usautoparts.com. So, since he can process their RMA's clearly Car Stuff and thebenzbin are linked. Plus, now I have another internet address, usautoparts.com.
If you go to the BBB for southern California and check out usautoparts.com, they have an F rating.
http://www.labbb.org/BBBWeb/Forms/Business/CompanyReportPage_Expository.aspx?CompanyID 0006368
I'd stay away from all the above companies.
I finally got the header pipe from Rusty's MB parts. He told me right away that the header pipe was now only available direct from MB. And he got it for me quickly at a good price.
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Interesting story. I realized quite a while ago that thebenzbin was just one of the names that the company was using, and that prices for the same parts were often different on their various websites. I've been dealing with thebenzbin for years, however, and never had a problem with them: in fact, the parts have usually arrived in a day or two, and the prices were reasonable. Germanstar.com has also been good.
The one company I did have a problem with was Adsit -- particularly with there ALL SALES ARE FINAL policy, since they sent me the worng part, and I eventually had to go to my credit card company to resolve the problem for me.
Good luck on your problem!!
On Thu, 3 Jan 2008 10:13:40 -0800 (PST), " snipped-for-privacy@optonline.net"

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Thanks for the advice, Per. I took the car over to an independent that I've used before, and he also seemed to think it was the tensioner, based on the sound I described. But I'm also going to going to order a chain and guides, just in case it ends up needing them, too, since it will sooner or later.
Regards
On Thu, 03 Jan 2008 10:20:26 +0100, Per Erik Jorde

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I have owned 380SE for 12 years... I know all about this engine.
If the hydraulic lifters are not working properly due to extended dino oil change, the valves will give you a tapping sound
Chain will stretch no matter how you put it. 180K miles is long enough and should be changed along with the guides and tensioner. I never done this because I sold the car and it wasn't long before an inspection station technician decided to rev the hell out of the engine to pass the inspection... Ended up I believe the chain slipped and car ran rough. I felt bad but it was great running car when I sold it.
I have done valve stem seal job myself... It is not too bad but takes alot of time to do it.
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