i was looking at a lawn tractor the other day that was sitting for about 2 years i think,,, i was going to buy it and take the motor out of it to put in mine,, it was a 12hp i/c briggs motor in it.. i took the sparkplug out and there was rust on it and tried to turn it over by hand but it wouldn't move.. the belts are off so that not the problem.. could there be rust on the piston rings, if so what else could be rusted on the inside and what could i do to get this motor up and running.

First if there is oil in it and the starter gear is not engaged or stuck to the flywheel it should turn over,rust on plug, indicates possibly a valve may also be stuck which will stop the engine from turning over,go underneath,put a five eights or nine sixteenths socket whichever you find fits the nut on the botttom of the engine pulley and try to turn engine this way,you should be able to turn it unless a rod is broke,if it turns only so far, pull the eight to umpteen bolts on the head and check for stuck valve,if only a stuck valve, you probably have a fair used engine,you probably need to clean the head anyway,carbon builds up pretty often over the hours of operation also.




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First, check and change the oil (this will drain any metal flakes out if it was run low of oil out and give you a perspective on it)..... secondly since this is a I/C, they have cast iron cylinder sleeves.... these will rust and you say you saw rust on the plug? Outside or in? You probablly have a lightly rusted bore and the piston rings are stuck to it..... spray some fogging oil down the plug hole.. Its either that or its seized from lack of oil.

thanks for your replays guys,, the engine did have oil in it and the rust was on the inside of the plug(the part thats inside the head). so if the valve is stuck what can i do to get it unstuck. will there be any internal rust to worry about on the crank or anything. i know i will have to clean the carb, o one more thing i noticed the rubber tube coming from the crank case breather was off, will that effect anything i dont think it will,, thanks

thanks for your replays guys,, the engine did have oil in it and the rust was on the inside of the plug(the part thats inside the head). so if the valve is stuck what can i do to get it unstuck. will there be any internal rust to worry about on the crank or anything. i know i will have to clean the carb, o one more thing i noticed the rubber tube coming from the crank case breather was off, will that effect anything i dont think it will,, thanks

I was given an engine with very similar problems last year. I think it was Bugman that actually told me this so sorry for stealing your thunder in advance. What I did is put some MMO (Marvel Mystery Oil) in the plug holes and let it sit overnight. Then, I removed the heads and got rid of the rust on the cylinder walls with fine sand paper. I replaced the intake manifold and all that crap because it was cracked and is how the moisture got in there in the first place. A couple of new head gaskets and an oil change later it fired right up. This engine is on my primary mower and running well. It is a twin cylinder 18HP.

Just be sure and find out HOW the moisture got in there or they'll be issues.

My 2 cents...

Ahh yes... wonder how I could forget the MMO..... (marvel mystery oil) its some good stuff.
Was the air filter punched through or missing? moisture can get through here. The breather tube missing shouldn't have done anything (just be sure to replace it)

On mine, it was the intake manifold that was cracked that allowed water in. Here's the thread to bring up some old nightmares for me:

http://www.hobbytalk.com/bbs1/showthread.php?t=121365

guess what the guy called me back today and told me he was going to keep the tractor and fix it up,, o well,, but thanks anyways for your help guys

Yeah...... this is usually the case when someone gets a looker.... It'll probablly sit there till he throws it away.

the guy called me back and i got it.. anyway,, a valve was stuck,, the carb is messed,, got to clean it(but had one from my 8hp to get it goin) the cylinder wall were caked with rust on the bottom (water got in it) but got it all off,, but before i started sanding it looked like it was a alumminum bore,, anyway i got it goin and it works good,, o and i had to take the started off my 8hp too. could you tell me why there is no cast iron bore in this or was i just seeing this (it says it on the engine cover) ,,, thanks

There is the possibility of having the cover swapped.... but if there was rust on it, then it was more then likely a cast iron sleeve.

i'm pretty sure its a 12hp i/c because the fella that had it had no reason to change the cover,, anyways it has lots of compression and runs good ,, i sanded off all of the rust off and it works good(there was water laying in the bore),, all i need to buy is a seat kit for the carb and change the oil,, thanks for your replays

i'm still wondering if this is an i/c,, is there anyway a alumminum bore could get rust caked on the bottom and little specks caked on the top,, there was deffinitly was water laying in the bore cause i can see the marks,, is there anyother way to tell that this is an i/c other than the bore.. like the piston,, i noticed it had a notch in the top that was deffinitly from factory i guess to line the rings up,, is this only on the i/c?? anything other than that different on a powerbuilt than an i/c,, thanks