Piston soak for noobs

[Dave Sherman]

I'm finding a bewildering array of info. The Lincoln has low compression on two cylinders, and it's pointing toward sticky rings. It's a flathead V-12 engine. I can see the valves opening and closing, so thankfully they don't seem to be stuck despite being dormant for a long time. It's making some blowby when it runs, so the crankcase is filling with some fumes. If I turn the engine so the valves are closed on the weak cylinders, blowing some compressed air through through the spark plug hole with the compression tester I'm seeing some fumes wafting out of the breather tube. No noise at the exhaust pipe or carburetor, so I'm reasonably certain it's the rings. Figured it's worth a shot to try it at least, maybe I can avoid a significant amount of disassembly.

What is a good strategy? I gather B-12 is a favorite, but it would leave the cylinder dry. Would MMO do anything for it? I would plan on cranking it until the valves are closed, filling the cylinder completely, and capping it loosely with the spark plug. Turning the engine by hand is quite difficult; it's heavy and the fan is driven directly off the crankshaft.

 

[Kira]

What year and how many miles on it?
Are the two suspect cylinders on the same bank?
Are the two cylinders adjacent?

I don't think "leaving the cylinder dry" is a big deal.
Mist some oil into the cylinder(s) when you're done.

 

[Brian123]

I'm finding a bewildering array of info. The Lincoln has low compression on two cylinders, and it's pointing toward sticky rings. It's a flathead V-12 engine. I can see the valves opening and closing, so thankfully they don't seem to be stuck despite being dormant for a long time. It's making some blowby when it runs, so the crankcase is filling with some fumes. If I turn the engine so the valves are closed on the weak cylinders, blowing some compressed air through through the spark plug hole with the compression tester I'm seeing some fumes wafting out of the breather tube. No noise at the exhaust pipe or carburetor, so I'm reasonably certain it's the rings. Figured it's worth a shot to try it at least, maybe I can avoid a significant amount of disassembly.

What is a good strategy? I gather B-12 is a favorite, but it would leave the cylinder dry. Would MMO do anything for it? I would plan on cranking it until the valves are closed, filling the cylinder completely, and capping it loosely with the spark plug. Turning the engine by hand is quite difficult; it's heavy and the fan is driven directly off the crankshaft.

You have a 1947 Lincoln, how long have you had this Lincoln?
A flathead V-12, I remember when I drove a Pontiac Chieftan, maybe the year of this car was 1952 or 1953, it had a Flathead V8

B-12 over MMO for a Piston Soak, the turning the Engine thing, have you tried taking the belts off?
I am having a feeling that BGR EP 109 or Valvoline Restore and Protect might not work. I have 2 gallons of Valvoline Premium Blue Restore 10W-30 sitting on my desk, that might not work. My thought is that motor oil's that were available from 1947 up until the early 1970's when Amsoil and Mobil 1 came out, they were not good, meaning with today's standards.

You could always do the B-12 thing, and then put some MMO in there, meaning a little bit of MMO to lube the cylinder before you start the engine. Has this engine been rebuilt or taken apart?

I need to ask this question, does your 1947 Lincoln look like the Mercury that Stallone drove in the 1986 Movie Cobra?

 

[Propflux01]

If it has been sitting for a length of time, perhaps getting a borescope and looking inside the cylinders will help, maybe rust on the cylinder walls causing the low compression.