Kohler magnum 18 only turns half a turn

[Mudrig150 315]

So I bought a kohler magnum 18, it only turns half a turn. Could this be a broken rod or a stuck valve? It has oil and it seems a bit black but it's not silver, so I'm thinking maybe stuck valve? It has been sitting for a while.

[Achto 29,229]

23 minutes ago, Mudrig150 said:

So I bought a kohler magnum 18, it only turns half a turn. Could this be a broken rod or a stuck valve? It has oil and it seems a bit black but it's not silver, so I'm thinking maybe stuck valve? It has been sitting for a while.

 

The valves on a L / flat head engine would not be able to come into contact with the piston.  I'm thinking that you may have a broken rod. Pull the heads off & see what's moving & what's not when you turn the crank.

Edited June 5, 2019 by Achto

[Mudrig150 315]

Yeah but if they were stuck they would stop the camshaft, effectively stopping the engine. Our little clinton had a stuck valve and it acted like a seized, broken rod.

[Achto 29,229]

3 minutes ago, Mudrig150 said:

Yeah but if they were stuck they would stop the camshaft, effectively stopping the engine.

 

This is true. Best bet would be to pull the heads off & see what moves & what doesn't. 

Edited June 5, 2019 by Achto

[Mudrig150 315]

I'm hoping it's just multiple stuck valves, even that would be easier to fix then a broken rod. The oil looks dirty but it doesn't show any characteristics of something broken, such as metal particles.

[Achto 29,229]

It looks like you would need to remove the intake & exhaust to get at the valve covers. This would allow you to gently push on the valve spring to see if your valves are free. But I think that pulling the heads to see what's going on might be easier and require less gaskets to reassemble. Hope it's not too serious. Let us know what you find.

[Mudrig150 315]

Luckily for me it looks pretty nice, and doesn't appeared to have been sitting outside, but in the kid's little shed.

[Mudrig150 315]

Any openings into the block to check if it has broken rod, or do I have to split it?

[oliver2-44 10,567]

If your not in a hurry, you might drain the oil and fill everything (crankcase, cylinder. exhaust, intake) full of diesel. Let it set and each day rock the crankshaft a little to see if it would gradually move more and free up.

[953 nut 59,221]

7 hours ago, Mudrig150 said:

been sitting outside, but in the kid's little shed.

Could be the mice have built enough nests under the flywheel cover to keep it from turning. You need to remove them and clean the cooling fins anyway.

[19richie66 17,598]

Check the flywheel magnets. Had all of them come off a flywheel. Ran good and then when I shut it off, a small piece caught a pole on the stator. Instant lock up. Moved back and forth a little but when you hit the key, it jammed and acted like it was a broke rod. Toasted the stator but I have another for it. Pulled a spare flywheel and it was the same way. 

[Mudrig150 315]

Figured it out. As it turns out, the engine does not have a stuck valve or broken rod. What it does have is over 1/8 inch of rust buildup in the bore. I was using super low grit sandpaper and wasn't even making a dent. Guess I'll just need a new jug.

My brother suggested it may have had water in it but the carb plates are clean and the intake has no rust in it. My hypothesis is just water vapor getting in through the open valve.

Edited June 8, 2019 by Mudrig150

[Achto 29,229]

43 minutes ago, Mudrig150 said:

Guess I'll just need a new jug.

 

If the jug is removable, you could possibly just have the rusty jug machined and install a new piston & rings on that side. Just a suggestion. 

 

A .010 over piston on one side will not hurt any thing at all.

[ZXT 2,401]

Any pictures of the rust in the cylinder? I've had more than one engine sit full of water forever and clean up with a hone and run great.. If the cylinder isn't pitted, it will probably clean up.

[Mudrig150 315]

One side is clean and a bit wore out but the other? Oof.

[953 nut 59,221]

From the looks of that intake valve I think we know where the water entered the cylinder.

Edited June 8, 2019 by 953 nut

[Mudrig150 315]

It's wierd, there's no rust or corrosion in the intake but rust in the cylinder. That side had an open valve, and so did the other side but somehow the one side fogged itself...

[ZXT 2,401]

Do you own a hone? Roll that piston to the bottom of the cylinder and see how it cleans up. You never know..

 

The reason there isn't any rust or corrosion in the intake is because that's not where the water stood.

[Mudrig150 315]

Nope. We had a hone but it's a 3 legged hone and its minimum size is 4 inches. The cylinder is something like 3.550.

[Mudrig150 315]

Finally got it to turn! Went to town with our little glaze breaker and after a bit managed to get it to turn all the way over.

[Mudrig150 315]

So I cleaned up the bore a bit more, now the bore is nice and smooth enough, can't get the tiny raised edge out, but it's good enough.

[ZXT 2,401]

5 hours ago, Mudrig150 said:

So I cleaned up the bore a bit more, now the bore is nice and smooth enough, can't get the tiny raised edge out, but it's good enough.

Raised edge at the top of the cylinder? That's just a ridge worn into the cylinder because the top ring doesn't go to the top of the bore.. Might indicate that the engine is pretty tired but won't affect anything as far as it turning over. 

[Mudrig150 315]

It's a raised bit where the rust was. But it cleaned up really nicely, due to it being vapor rust and not water rust.

[Mudrig150 315]

Here's the improvement:

Before

After

Just need to throw the heads back on and run er. (Note: That spot is rust staining, not pitting. It's slightly raised, not indented.) It's even still close in spec.

[Mudrig150 315]

Well after doing more work in this motor, such as getting the oil filter removed and getting some things adjusted. Still need to order my remote oil filter and get the heads back on.