Every time I change oil in my '90 420SEL, I have the problem of loud rattling upon initial startup from everything being dry of lubrication. The engine parts sound as if they are going to literally swarm for a good three or four seconds at startup. It is scary.

I currently us a MityVac system to extract the oil, but I get the same circumstances if I drain the crankcase in the old-fashioned way. I have even tried cranking the engine several times, and quickly turning the key off before the engine can start with no effect on this problem even when I crank a dozen or so times or more.

Two questions, really: What is the underlying cause of this other than the obvious of dry bearings and oil pump, in other words is this some engineering or design flaw? Does anyone make a pre-oiler that can be installed on the engine in order to get a little lubing happening prior to startup? I've seen pre-oilers on some RV's. I'd appreciate any help as I can just imagine the damage these dry starts are causing my engine. TIA.

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1980 300SD 146K miles.

what you are hearing is the beginnings of the 420 death rattle.the chain has stretched and when you drain oil it is also draining out of the chain tensioner.the noise you hear is the time period as the tensioner fills with oil and tightens the chain[about 4 secs] suggest that you plan on replacing chain and tensioner soon and check all three of the upper chain rails[one on the right and two on the left].

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David S Poole
European Performance
Dallas, TX
4696880422

"Fortune favors the prepared mind"
1987 Mercedes Benz 420SEL
1988 Mercedes Benz 300TE (With new evaporator)
2000 Mercedes Benz C280
http://www.w108.org/gallery/albums/A...1159.thumb.jpg

Sounds expensive .

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1996 E320 since 1/16/08, 171K miles as of Feb 2011

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1989 300CE - R.I.P. Dec 29 2007
Other MBs (sold): 1992 300E-24 - 1979 350SLC - 1984 230E - 1990 300CE

Moderately. My independent did it for me back in 2002 for about $600. On the other hand, if it means another 100K miles on a car you love, it's pretty small change.

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-- Paul W. (The Benzadmiral)
('03 Buick Park Avenue, charcoal/cream)
Formerly:
'97 C230, smoke silver/parchment; '86 420SEL, anthracite/light grey; '84 280CE (W123), dark blue/palomino

Another thing you may try is to disconnect the coil wire from the ignition control module. You can then crank the engine without it starting. I did this for quite awhile but then this February I had the chain and tensioner and upper guides replaced. Good thing because we found a few broken pieces of the chain guides.

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95 E420 ( 76K) SOLD
85 380SE(125k)
95 SL500(72k)

Yes that is just looking for a slap in the wallet. get to it don't procrastinate.

Not exactly what I wanted to hear. The engine has only about 30K miles since new chain, and I have been having this problem since the first oil change I performed on the vehicle. I'll have my mechanic look into it, but someone please tell me there is a simpler solution. If it has to be, it has to be, but the man that replaced the chain before my purchasing the car is about as trustworthy as they come. Any other possibilities?

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1980 300SD 146K miles.

You might try to fill the oil filter before installing. This was suggested on another make of car I owned.
Anziani

you may just need a new tensioner.

That sounds like a good idea. I'm assuming I can just put the filter into a seperate container and add oil as needed until it is saturated prior to installation? It occurs to me that filling the filter housing would not work because all the oil would drain into the crankcase. Next oil change, I'll try filling the filter, first, then crank the engine with the coil wire disconnected until I see pressure on the guage. Any other thoughts? Are my assumptions correct in regard to filling the filte with oil? Thanks.

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1980 300SD 146K miles.