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!

[Tomguy]

Can you turn it backwards at all? If you can't even go back, that would likely rule out something like debris wedged between a piston and the head.

It sounds like someone doing the distributor probably dropped a nut or socket in the intake. If so you'd be able to turn it backwards but not forwards. If you can turn it back until the timing chain slack is taken up and then it stops, it would indicate a binding camshaft. If you can turn it back a bit and then it binds before 15 degrees or so, it would likely be a skipped timing tooth causing valve and piston interference.

If you can't turn it backwards at all either the bottom end or something in the trans is locked up. I don't think a locked up torque converter would prevent you from being able to move it in neutral.

[Tony H]

Is it stuck in both directions? Is it totally seized or is there any movement? Was it stored for a long time before you acquired it?

[rbtoj]

Originally Posted by ctsandb

...He drove it home and then then next time he went to start it the engine was seized.

How long was it between "drove home" and "next time"? I'd expect an engine to seize over years of inactivity, not over night, unless something was very very wrong to begin with.

Did you take the oil pan out to see if there is anything in the bottom half that could be wrong?

[ctsandb]

Originally Posted by Tony H

Is it stuck in both directions? Is it totally seized or is there any movement? Was it stored for a long time before you acquired it?

Yes, it is stuck in both directions. There doesn't seem to be any movement at this point. I am not sure how long it was stored before I got it. When I first talked to him, it didn't sound like long but now after working on the car, I wonder. The tire treads look practically new but there is some slight cracking showing that they have been on for a few years.

Originally Posted by rbtoj

How long was it between "drove home" and "next time"? I'd expect an engine to seize over years of inactivity, not over night, unless something was very very wrong to begin with.

Did you take the oil pan out to see if there is anything in the bottom half that could be wrong?

I need to get back with the previous owner to get some more information. I'm hoping he'll be honest about it all. I just need the information at this point. I'm happy with the purchase and just need some clarification. I am beginning to suspect that it had been sitting for quite some time. I'm not sure how much was between him driving it home and trying to start it the next time and how much time was after he found it to be seized.

I think it's a good idea to take the oil pan off. The oil is clear and looks new on the dip stick - so no opportunity to feel for metal or anything. I haven't looked at how hard it is to get the oil pan off. Surely it's easier than the starter!

Thanks!

[Rick76]

I wonder if borescopes can be rented.
It's possible that antifreeze could have leaked into one of the cylinders from a head or intake gasket failure. This can happen from the wrong coolant or not being changed frequently enough (an often neglected maintenance item).

[ctsandb]

Originally Posted by Rick76

I wonder if borescopes can be rented.
It's possible that antifreeze could have leaked into one of the cylinders from a head or intake gasket failure. This can happen from the wrong coolant or not being changed frequently enough (an often neglected maintenance item).

I'm checking around to see if I can get one. I saw some on Amazon that basically hook into you phone for around $20. The dedicated ones seem to be $80 for the cheapest at Harbor Freight and up to the
$100-$200s elsewhere. Thanks for the suggestion.

[ctsandb]

Originally Posted by Rick76

I wonder if borescopes can be rented.
It's possible that antifreeze could have leaked into one of the cylinders from a head or intake gasket failure. This can happen from the wrong coolant or not being changed frequently enough (an often neglected maintenance item).

Good idea! I ordered a $20 one that'll hook up to my iPhone today. I looked at the process for taking off the oil pan and I think I want to avoid that if I can! I can use the bore scope to look through the oil plug too to see if I can see anything amiss on the bottom end.

[optimusprime]

Last one i had like this i used an old spark plug base and welded a steel tube to it .I then filled up the cylinder 3/4 with diesel pop the spark plug back in the hole and conected it to my compresor .Then just apply a little pressure not to much .

[ctsandb]

So I got a borescope and the cylinders look ok. They aren’t mirror shiny but there is very very little surface rust.

Today I jacked up the rear end and tried to turn the engine by the crank but but again there is nothing. I reinspected the cam and valves but everything looks ok from the outside.

At this point, the only thing I can imagine is something with the crank. I’m going to try to go through the oil plug today with the borescope and see what I can see.

Am I missing something. If something fell down the intake when they were changing the fuel distribution block there isn’t anywhere it would go to cause the engine to be 100% locked up in both directions, is there?

I need to get ahold of the previous owner. This isn’t making sense! Or am I missing something?

[Frank Reiner]

Originally Posted by ctsandb

So I got a borescope and the cylinders look ok. They aren’t mirror shiny but there is very very little surface rust.

Today I jacked up the rear end and tried to turn the engine by the crank but but again there is nothing. I reinspected the cam and valves but everything looks ok from the outside.

At this point, the only thing I can imagine is something with the crank. I’m going to try to go through the oil plug today with the borescope and see what I can see.

Am I missing something. If something fell down the intake when they were changing the fuel (distributor) (FD) distribution block there isn’t anywhere it would go to cause the engine to be 100% locked up in both directions, is there?

I need to get ahold of the previous owner. This isn’t making sense! Or am I missing something?

While changing the fuel distributor (FD), even if something were dropped into the air guide it would first have to get past the throttle plate, and would then pass into the intake plenum which is at the lowest point of the intake system. It is very unlikely that air flow would lift something dense, like a screw or nut, off the bottom of the plenum and carry it up through a manifold runner and into a port.

As to the crankshaft, there are two remote possibilities:
1) That the neck of the torque convertor cracked, and has become wedged in the bushing of the primary pump of the transmission.
2) That the oil pump, or oil pump chain failed while the engine was running, and that the main and/or rod bearings did not seize until the engine was shut off.

[rbtoj]

Originally Posted by ctsandb

So I got a borescope and the cylinders look ok. They aren’t mirror shiny but there is very very little surface rust.

I'd say there is your problem. The cylinder walls allways have a very thin coating of oil. When you park a car for too long, this oil slowly drains away, and only then you have surface rust forming.
So if the car wasn't parked for long there should be no rust at all.
To me, it sounds like the previous owner is lying.

[garyd75]

if you need an engine ive got a complete one with bolt on's and with transmission that was running and driving before pulled Last month. ive ogt a video of it running. it will need new rubber hoses and gaskets. has 110k miles on it. came out of a 1976 450sel w116. located in Goldsboro nc. will need new gaskets
750$ for everything

[optimusprime]

May be its had head problems , and getting in to the engine and the coolant can rust every part up as if it was welded.