5 Problems.

[LaWn GuY]

Ok first off this 12 HP flathead engine replaced my 13 HP Tecumseh, which Im currently looking for another. But anyway I don't know the history of this engine, the shop Installed It last year. It never ran quite right even when the guy drove It off the trailer and Into my driveway.

Problem 1: Doesn't run right. Adjusted carb/disassembled and cleaned. If I adjust It to run good at full throttle It runs poor at Idle and if I adjust It to run good at Idle It runs poor at full throttle.

Problem 2: When at full throttle sitting or driving without the blades engaged you can hear It misfiring. But goes away when put under load (blades engaged).

Problem 3: Change the oil a few days ago and found glitter and gray oil. New oil was gray after only 1 minute of running. Used 10W30 Castrol

Problem 4: Pulled spark plug and cranked It over and got a mild slapping/knocking noise. Will upload video If needed.

Problem 5: When restarting hot It sometimes puffs blue smoke for a second.

Engine runs fine no noises/knocking when running. Starts as soon as I turn the key. But as I said I don't know the condition/history of this engine, It runs ok, but I know It can do better. I thoroughly cleaned the carb with no change also changed fuel filter, spark plug and air filter. Even ran a higher octane with no change.

Not sure If I should rebuild this engine over the winter or what.

This engine Is pretty old around the 80's engine number 281707

 

[bertsmobile1]

6 problems actually.
The shop !
I give 12 months parts & service on used mower engines and 2 years if it is in a mower.

1) carb has wrong govenor spring, or air leak or blocked idle circuit ( or all 3 )
2) Any one of the 3 above
3) Alloy in the oil heading for a catastrophic failure, one of the bushes have gone and good reason to retire it now before it tosses a rod.
4) See 3 Worn cam bush will do this as the valve springs compress & relax. counterweight con rod will exhibit the same symptoms.
5) Hanging valve, float level too high blocked float breather.

I would pull this engine down now.
You might be lucky and it could be something easy but once you get a ventilated crankcase it is scrap metal.
The most common problem I come across which dumps grindings in the oil is top bushes seizing on the crank ( low oil , running along a slope etc )
Next is the counterweight rod wearing