Oh No! What did I do to my engine? Reassurances Please! (long!)

[kang]

This is why dealers charge >$200 for an oil change. Of course they get dealer mark-up for M1, something like $7.99 a quart, plus mark-up for the filters.

One thing that link doesn't mention is just how fast 10 quarts of hot M1 come pouring out of the sump tank when you remove the plug....

It also doesn't emphasize using a "large oil pan” enough. Your standard oil pan won’t hold these 10 quarts of hot M1…


Luckily I knew of both of these points before I attempted my first oil change.

 

[kang]

To make things more interesting, this report is based on the oil that was in the car when this happened:

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=next_topic;f=24;t=002328;go=newer

 

[SWS]

Hi Kang,
Some late '60s cars used to "diesel" when shut off, and I watched several of them do it. In some cases they would start spinning BACKWARDS for several seconds. I also read about that characteristic in a car magazine, so I assume that it was rather common. It was said that the hot spot in the CC would light the fuel so early as the piston was rising on the compression stroke that it would force the piston back down, thus making the engine spin backwards. Anyway, if this is the case, then the oil pump is not working, the crankshaft bearings have no oil pressure but there is compression / combustion putting metal-to-metal force on the bearing, and the cam lifters are riding up the "wrong" side of the cam lobes, which may or may not be OK depending on the entry / exit profile. I think that this would be damaging to some degree.

If your engine was spinning FORWARD while dieseling, then that is a better case. I don't know why it would make loud metal bangs, but perhaps several cylinders were dieseling with different "timing" and actually fighting each other through the crankshaft.

All of the above is opinion & hypothesis - I am not a mechanic! If your engine is running OK now, then everything is probably OK. However, I agree with the others that you should change the oil.

Best Wishes as you motor along!

 

[kcryan]

Beautiful car

 

[kang]

Thanks kcryan.

SWS, there was no indication the engine was going backwards! This event was almost two months and 1,500 miles or so ago, and the engine is purring along just fine. The further I get from the even the more confident I am that the engine is fine. Now I’m thinking the banging might have been the timing chain slapping.

I did an oil analysis. The results are here:

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=3;t=002858;p=1

 

[SWS]

Kang, I'm glad to hear that all is OK after 1500 miles!

 

[Eddie]

Clean the throttle body. Comon symtom is poor idle and just above idle.