[JamesSouth]

This spring, on my first use of the season I heard a somewhat loud bang and stopped to see if I'd hit something, negative. But as I continued to mow the tractor acted as if it does when mowing overly tall or very wet grass, bogging down. The condition never improved and now there is this vibration that occurs at about one-half throttle with the mower deck not lowered or engaged. Any help is appreciated.

 

[Gregbkk]

Not sure which engine is in your mower. Is it a twin cylinder?

 

[denverguy]

Sounds like you may be running on one cylinder, the question is why?

Any chance you have a compression tester? If not, you can see if it still runs on one cylinder by alternating pulling plug wires. Just use something insulated to remove the wire so you don't get shocked.

Perhaps one of the Briggs Vanguard experts will chime in soon.

 

[Herminator]

Sounds odd but a friends 425 was doing this. Ended up being the top part of the spark plug had come loose and it was running on one cylinder. Could also be a cracked plug.

 

[JamesSouth]

Not sure which engine is in your mower. Is it a twin cylinder?

Briggs and yes twin.

 

[JamesSouth]

Sounds like you may be running on one cylinder, the question is why?

Any chance you have a compression tester? If not, you can see if it still runs on one cylinder by alternating pulling plug wires. Just use something insulated to remove the wire so you don't get shocked.

Perhaps one of the Briggs Vanguard experts will chime in soon.

Thank you, I will try pulling one wire, then the other. Would pulling the plugs and inspecting them reveal anything?

 

[JamesSouth]

Sounds odd but a friends 425 was doing this. Ended up being the top part of the spark plug had come loose and it was running on one cylinder. Could also be a cracked plug.

Was it a plug issue or did the wire come loose from the plug? Thank you.

 

[Gregbkk]

As herminator stated, make sure you're getting spark to both cylinders.
Hopefully you didn't bust a rod. Easy way to check is pull both plugs out and use a drinking straw or some such utensil to insert into spark plug hole and rotate engine to verify pistons are doing what they're supposed to do. Stick straw or whatever in until it contacts piston, keep enough pressure on straw as you slowly rotate engine.
Let us know what you find.

 

[JamesSouth]

As herminator stated, make sure you're getting spark to both cylinders.
Hopefully you didn't bust a rod. Easy way to check is pull both plugs out and use a drinking straw or some such utensil to insert into spark plug hole and rotate engine to verify pistons are doing what they're supposed to do. Stick straw or whatever in until it contacts piston, keep enough pressure on straw as you slowly rotate engine.
Let us know what you find.

Will try your suggestion. been using push mower to keep up for now. Thanks

 

[Herminator]

Was it a plug issue or did the wire come loose from the plug? Thank you.

The little piece that the plug wire snaps onto unscrewed off the top of the plug. It could just be a bad plug and that is an easy fix and while the plugs are out the checking if the pistons are moving is an easy check.