Seized engine - 77 450sl

[ctsandb]

I recently purchased a 77 450sl. The exterior and interior and pristine, which would be even more outstanding if the engine wasn’t seized but I was able to get it for a good price.

The previous owner said that he had a new fuel distributed installed and had the oil changed. He drove it home and then then next time he went to start it the engine was seized. He didn’t report it having been overheated or having ran out of oil. Nor does it appear the oil was diluted with coolant or water (based on the oil left in the valve train bolts and nooks and crannies). The car had been garaged and not left out in the weather.

Since I have had the car, I have removed the spark plugs and soaked the pistons. I have removed the starter with the thought that the starter might have been stuck in the flywheel. I also removed the belts in case any of those components were stuck. However, so far, I have not been able to get the engine to budge by turning the crank via the crank bolt.

I took off the valve covers and the timing chain seem tight and chain guides are in place and not broken. The cam lobes look ok and there doesn’t seem to be any obvious signs of being ran without oil. I don’t see any obvious signs of trauma to the valve train.

We have pushed the car into the garage, so I don’t think the torque converter is stuck.

Is there anything else I should be looking at? From what the previous owner said, it seems strange that the engine would be locked up. Is it possible that sometime might have dropped down in the engine and caused some interference? If so, where would I look?

Any help for suggestions would be appreciated!

[salabellera44]

Take oil pan off, raise car to look under of any broken connecting rod that got stock at side of block. if clear, need to use long screw driver to turn crankshaft. no turn crankshaft seem frozed. loosen all connecting rod bolt and turn it. Goodluck!

[Frank Reiner]

ct:

In mid-October you made the same post in Vintage.
Do you expect different results now?

A. Einstein defined insanity thus:

"Doing the same thing over & over, and expecting a different result."

[tyl604]

Yes, thought I recognized this one.

[ctsandb]

Originally Posted by Frank Reiner

ct:

In mid-October you made the same post in Vintage.
Do you expect different results now?

A. Einstein defined insanity thus:

"Doing the same thing over & over, and expecting a different result."

A review of the timestamp from this thread and the one in the Vintage section will reveal that they were posted on the same day almost 45 minutes apart (October 17 at 4:48 p.m. and 5:34 p.m.). I understand that it is not appropriate to post the same message in two different sections of the same forum. However, as this was my first time posting to this forum, I didn’t realize how long it took for posts to appear. I assumed (feel free to respond with another overused cliché) that my first post was lost because I was posting from my home computer where our internet service is spotty at best. I reposted in the Vintage section because after further review of each section, it seemed that the SL section was more focused on newer SLs (though its still not clear where a post about a 70s SL should best go).

I appreciate your’s and the others comments and suggestions in the Vintage section and salabellera44’s in this section from Nov 5th.

BTW, I have always been bothered by that quote regarding insanity. I long suspected that it was misattributed to Einstein because it seems a gross overgeneralization for a scientist to make. Furthermore, it is simply false. I’ve pasted a few links to some articles on this overused, misattributed, and incorrect quote below.

Misattributed Quotes - Business Insider
https://skepticalexaddict.wordpress.com/2016/04/20/the-definition-of-insanity-is-not-doing-the-same-thing-over-and-over-and-expecting-different-results/
https://www.psychologytoday.com/blog/in-therapy/200907/the-definition-insanity-is
https://www.salon.com/2013/08/06/the_definition_of_insanity_is_the_most_overused_cliche_of_all_time/

[Mighty190]

Did it make an odd noises and did it do anything strange when you shut it off? Bottom end issues are usually really obvious. Another thing I've seen but is very loud is a torque converter bolt baking out.

If it just "died in its sleep" it pretty much has to be something leaking into the cylinders and either hydrolocking it or causing rust. Or maybe a messed up distributor if you're actually being gentile with it when you're cranking it.

[tyl604]

If you think this is a tough crowd, try going over to the LandRoversOnly forum and post a question about gas mileage. They will roast you.

The guys here are pretty civil and you will end up getting some reasonable answers. Just keep the faith.

[Mxfrank]

One thing that comes to mind is a bad fuel injector. If the injector leaks, it can hydro lock a cylinder on shutdown and prevent cranking. Pull the plugs and try to crank.

[Benz Dr.]

450SL's have a one piece oil pan so you actually have to pull the engine to remove the pan.

I have a piston and connecting rod from a similar engine that hydro locked and still managed to start. Bent the rod and smashed the bottom of the piston when it came into contact with a crank throw. Thing is it still ran although not well. A great illustration of the massive power that is contained in even a small amount of gasoline.

I've seen enough of these engines hydro lock to say that it's a good possibility. Problem now is what sort of damage was done to the cylinder/s after sitting for a prolonged shut down.

[alabbasi]

I would think that you have a poorly rebuilt fuel distributor that's dumping fuel into the engine. Remove the plugs and see if you can spin the engine. You may have bent some valves. If beyond repair, I have a Euro 350SL , high compression motor that I can part with.