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Discussion Starter #1
I wonder if anyone can help me with some advise. My 1982 380sl died on the highway the other day. While I was looking at the engine trying to figure out what was wrong a helpful person stopped and said he knew alot about Mercedes engines. Now I have read that you should never turn the engine counterclockwise. While I watched the helpful person turned the engine to top dead center in a counterclockwise rotation. The engine after that sounded worse while cranking it. Does anyone know what happens when you do that and am I in for a large bill?

Thanks for any help.
 

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Forget about what he did. More info. would be needed on that anyway.
Why it died is more important. Back to the basics. Spark and fuel.
 

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Discussion Starter #3
Rowdie thanks for the responce. First thing I noticed was that it started idling a little rough. Still at 500 rpm but rough and the vacuum guage, which always was to the left at idle moved to about a quarter to the right. At cruse speed it would be about half way. The next day I took her out and noticed that when I increased the accelator it made no difference. I would floor it and it would do nothing. Then about a few miles longer it started banging and stopped. At first I thought it was the fuel but after the engine was rotated by hand it makes a grinding noise somewere in the front and it backfires. I am thinking that there may be something with the distributor or maybe a chain tensinor broke. I don't think that a fuel problem would make the engine backfire. I did notice one thing that when the engine is rotated by hand the distributor does not rotate but when it is rotated by the starter it does rotate. Any ideas would be appreciated.
 

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Wow. Here are a few Q's to help us understand.

1)
Have you pulled off the valve covers and checked the chain stretch? This is SO much easier than it sounds. Pull the passenger valve cover, and turn the engine to the point where the marks line up on the passenger cam. Check the timing marks on the harmonic balancer to determine your degrees of chain stretch. This is possibly a 10 minute job.


2)
Rotation Direction: Let's confirm it.
When you are looking at the engine from the front of the car, which way did the pulleys and harmonic balancer turn? Clockwise or counter clockwise?

3)
Can you check to see that the distributer / rotor points to the TDC mark when the hanmonic balancer shows the TDC mark. Is it lined up or not? (It needs to be lined up.)
 

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Time to pull the valve covers and look. Align the cams at TDC on the Balancer.
Does it still have the single row chain?
 

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Discussion Starter #6
Thanks for the information. Rowdie: I will pull the covers this weekend. Fonzi: the engine was rotated in a counterclockwise direction as you stand in front of and face the engine. I will check the distributor this evening when I get off work.
 

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Discussion Starter #7
Rowdie: The chain is a unique story. It may have some bearing on the problem. After I bought the car I found out that the PO had blown the 380 engine. He replaced it with a 1989 420 SEL engine. Because of the differences in injection and distributor he put the intake and injection parts on the 420, he also put the 380 distributor on it.
 

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Discussion Starter #8
Fonzi: In reference to my timing problem. I pulled the valve cover on the passengers side. I noticed that one rocker arm was off and some of them were very loose. Is that normal? Second when I turned the crankshaft by turning the fan belt, the balancer turned but the distributor and the valve cam did not. It appears that the belt pully and harmonic balancer are not attached to the crank shaft. It may be that the key is broke. Does that happen much on Mercedes? Is that possible?
 

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I,m sorry to hear that. It sound like the chain broke or jumped a few teeth. In either case it is an expensive repair.
 

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Start from the start, does it have any stop in the rotation during cranking?
 

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Discussion Starter #13
Mercedes Mechanic, sorry but I don't understand your answer. Could it be that the key in the harmonic balancer broke?
 

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Discussion Starter #14
Not sure, when I crank it there is a grinding sound in the front of the engine, sounds like it is coming from around the distributor gear. After a rotation or two it backfires.
 

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TC broken is really the wrong term. It is usually a combination of things. The chain stretches. The guides break. The tensioner gets weak. If you still have the single row chain all all this will contribute to the TC maybe skipping a tooth or two on the sprockets then all hells breaks loose. Also applies to the double row chain but the single is more susceptible
 

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I had a crank shaft break in a Nissan 3.0 motor in a 1991 Infinit M30 convertible. I had the engine replaced at the dealer with a warrantied reman motor for nearly $5000.

Crank either way, it's screwed. Sorry man. That definitely stinks. If it's any consolation, I only owned my M30 for 3 months before the cranks shaft went. The only other major repair for the car was a trans rebuild. Overall the car cost me less than $3000 per year, which is about normal for most cars.

I wonder if you can take this opportunity to put a more powerful engine in the car. Maybe a manual transmission. It sounds like you know what you are doing, so maybe it's an option?
 

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Discussion Starter #17
Rowdie, thanks for that information. Is it normal for rocker arms to be lose when the cam lobe is in the top position. I realize I am hoping for a good solution but the part of the harmonic balancer turning but not the crankshaft has me baffled. Even if the TC has jumped a tooth or two would that stop the camshaft from turning when the harmonic balancer is rotated?
 

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Mercedes Mechanic, sorry but I don't understand your answer. Could it be that the key in the harmonic balancer broke?Not sure, when I crank it there is a grinding sound in the front of the engine, sounds like it is coming from around the distributor gear. After a rotation or two it backfires
Grinding sound is bad, but that does not mean it is not fixable. But at what cost? Lets say you have not bent the valves yet, then its just a chain and gear set with guides. Now lets say you bent the valves, its toast. Might as well get another engine.


Make it super easy for you, if the heads have to come off, find another engine, that runs hopefully. Then freshen up that engine, and happy motoring.
 

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The only thing that will stop the cam from moving is a broken chain. It is tight because it is wedged in there. Again - sorry.
 
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