Ferris 23 Hp B&S Engine Vibration

[Skippydiesel]

Ferris 48" Part No 5901740, B&S 23 Hp, Commercial Series, Model 44C777000 5 G1
Engine has developed a vibration, throughout rev range (deck not engaged)
Work done: Armature gap within specification. Valve clearances, adjusted. Spark plugs cleaned & gaped - good spark. Fuel supply - good. Air & fuel filters cleaned.
The vibration started when mower in normal work. Nothing unusual happening.
I am concerned that, having checked all that I can think of, something internal may have come adrift.
Please advise

 

[Rivets]

Can you better describe the vibration, as COVID has turned our crystal balls into snow globes. We are not standing next to you to see what you see. What color were the plugs you cleaned? I would start with new plugs, double check they are the right ones, and check whether both sides are firing. Might need to purchase two inline spark testers, so you can observe both plugs at the same time.

 

[Skippydiesel]

Can you better describe the vibration, as COVID has turned our crystal balls into snow globes. We are not standing next to you to see what you see. What color were the plugs you cleaned? I would start with new plugs, double check they are the right ones, and check whether both sides are firing. Might need to purchase two inline spark testers, so you can observe both plugs at the same time.

Mower has two ignition coils - have swapped & checked each spark plug - plugs out & grounded, cranked engine - good spark on each.
Plug colour - one good (light brown) other a bit dark but cleaned up okay.
I agree with new plugs - low cost and never know may solve problem.

 

[Skippydiesel]

Two new plugs - no change
Removed the hydraulic & deck drive system, from engine crankshaft/PTO - no change. So none of the belt pulleys or electro clutch, are causing the vibration.
Engine starts & runs just fine - vibration (I would describe as medium to high intensity) remains fairly constant (little change with rpm) throughout rev range (ie from idle through to full throttle).

Tomorrow will remove cowling & double check flywheel, however if it was loose/shifted somehow, I would expect the ignition timing to be out and its not.

Anyone familiar with this engine model - please advise if anything can come adrift internally (eg counterweight/balance shaft/etc that may result in engine vibration??????

 

[Tiger Small Engine]

Two new plugs - no change
Removed the hydraulic & deck drive system, from engine crankshaft/PTO - no change. So none of the belt pulleys or electro clutch, are causing the vibration.
Engine starts & runs just fine - vibration (I would describe as medium to high intensity) remains fairly constant (little change with rpm) throughout rev range (ie from idle through to full throttle).

Tomorrow will remove cowling & double check flywheel, however if it was loose/shifted somehow, I would expect the ignition timing to be out and its not.

Anyone familiar with this engine model - please advise if anything can come adrift internally (eg counterweight/balance shaft/etc that may result in engine vibration??????

Check the for engine mounting bolts for tightness. I see lots of loose bolts from customers and will cause lots of vibration of engine.

 

[Skippydiesel]

All engine mounting bolts tight - no sign of movement/fretting anywhere.

I did not describe the vibration accurately - at low/idle rpm much more/courser/violent vibration, so much so that the carburettor is visibly shaking, to the point I am concerned it may crack an inlet manifold. High rpm, vibration smooths/becomes much more rapid but still very significant.

Compression - turning flywheel by hand seems to be the same on each cylinder (not the most scientific test )

HELP!!!!!!

 

[Skippydiesel]

SOLVED!!!!!!!


One piston is not moving - stuck up.
I suspect connecting rod big end has separated - thats why there is no noise when cranked.

New Question
Without knowing what the damage may, be is this :

• A cost efective rebuild???
• Replacement engine???

 

[ILENGINE]

Most likely not cost effective rebuild unless you get really really lucky and nothing inside the engine is damaged Most likely 99.9% chance will require replacement engine.

And your response is typical of people that never realize that they are only running on one cylinder. People just don't know, and this is not anything that is against you. The typical customer issue is lack of power in cases where the grass in tall or they are driving up their hilly yards. On flat ground and normal grass cutting they don't notice.

 

[Tiger Small Engine]

Most likely not cost effective rebuild unless you get really really lucky and nothing inside the engine is damaged Most likely 99.9% chance will require replacement engine.

And your response is typical of people that never realize that they are only running on one cylinder. People just don't know, and this is not anything that is against you. The typical customer issue is lack of power in cases where the grass in tall or they are driving up their hilly yards. On flat ground and normal grass cutting they don't notice.

Yep. A customer will come in with problems and as soon as they start the mower, I know it is running on one cylinder. They just can’t tell.

 

[DaveTN]

Dang it! All I’m seeing in my Diagnostic Crystal Ball is some
homely looking girl from Kansas clicking her heels and
crying about trying to get her mower started back home and
the grass is higher than a wheat field…