Another thought as well occurred to me. At times owners have had semi seized engines. They ran but had little power from far too much internal engine drag.

If the chain checks out. You may or may not be able to rotate the engine now so you have to be observant. The clue was the substantial change with the new oil filter. That engine may have ran with substandard oil pressure or volume at speed. You never got it to speed so there is no way to know.

It is a long shot. Yet you want something to look for if the chain seems normal. I believe their oil filters are a bypass design though. Where if the filter element gets plugged the oil passes through other medium. That could restrict the flow eventually as well. There are people out there that really never change oil and filters. Or only the oil at best very infrequently. Usually when you remove the valve cover the evidence is obvious.

Also sludge can build up to the point of restricting oil supply to where it is needed. Somewhat like cardiovascular disease. Where the heart creates enough blood pressure. But system restrictions inhibit the function intended by the fluid under pressure. A seized up engine bearing problem is not unknown. I am not an oil change nut but these engine produce a lot of soot in the oil. The soot is bad so it makes oil changes more important than in a gas car to me.

I often wondered why these engines did not last longer. It was just a guess that they would last much longer if the base oil was changed out even more frequently than the factory recommends. I came from a time that every thousand or fifteen hundred was the recommended change frequency on many cars I owned. Oil was only about .25 cents a quart then though.

I think many of these engines approach 500k with their current owner unaware they have. Forty years at an average of 10k a year can do it.

My thoughts are just speculative in nature. No proofs as such are there. for example a cars base oil has a recommended time change period regardless of the low miles accumulated in the period. Even on the newest cars.

That makes me wonder if there is an oxidation problem that is time related to all the modern additives that go into engine oil. I just cannot extensively dig further into every thought I have. Or sulphuric acid does tend to accumulate or concentrate with time.

I normally don't turn engine at the steering pump. I normally turn engine at the pully. It is a moot point now if the engine cannot turn by the starter. If the chain snapped then the valves probably are bent. You need to remove the valve cover and/or the oil pan to take a look for sure. It is unfortunate but that is life. Good luck.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

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