I have a Snapper Lawn Tractor that was purchase in May of 2013 with a 20 Hp Briggs and Stratton Engine. Model 33M677 0110 G5 .
The Tractor has 150 Hours on the Engine Maximum. Every year the oil has been changed with new oil filter installed. So it has been well maintained. The Engine Ran fine with no issues all these years.
Then last fall the Engine had a Major Failure. It was running fine cutting lawn then like Sputtered and LOUD BANG. It Stopped. After lifting the hood it was seen the Whole Rear of Engine was Blown wide open. I mean the Whole Back at least 1” gap of Metal all the way across the whole rear of Engine. There where pieces of metal all over this area.
Looking at it you would think the Rod had failed somehow – the spark-plug was removed and it turns over by hand and still has compression so The Rod is not Broken as one would think.
The Engine is still installed in the tractor so it has not been taken apart yet to see what caused the failure.
Has anyone else seen this type of Briggs Failure and What is the cause?
Also does anyone know a Good Model Replacement for this Engine.
Looks to me like the counterbalance let loose. Carefully look at the oil and see if you find shavings. Normally when I see a hole like that I see oil everywhere. Not to be a wise guy, the only time I’ve seen that is when the engine was run low on oil. When you pull it apart try to collect as much as possible and see if you have more than a quart. Also look for signs of over heating.
This failure is some what common on 28, 31 and 33 Series engines until they changed the counter weight system on later engines. On older 25 and 28 Series flat head engines you could get replacement parts for the counter balance Eccentrics which helped some. Might want to consider what kind of oil you are using and change more often than recommended even.
Walt Conner
#5
7394
All your pics don't show any oil blown out..
#6
tom3
Could be if the engine suddenly locked there would be not a lot of oil splashed out? That blow out would sure ruin someone's day though.
Sorry if you took it wrong - was just saying the oil would be on the bottom by now.
Also still wondering what a good replacement Engine to replace this one.
Do not have any hopes bringing this one back to life.
Thanks
#13
Mkala
Wow it's well destroyed
Don't like that much big single cylinder like this.
Too big for one cylinder. After 15HP it's better to have a Twin (but not the same price, and can be complicated to re-power your mower).
31 series B&S will work fine and be a direct replacement except may have to check alternator which will interchange if necessary. Be a lot easier found if you are looking for a used one.
Any engine with the same output shaft diameter and length will fit.
Using the same brand & series just makes it easier as it is pull out drop in plug up & you are good to go.
Check out the surplus engine suppliers and the surplus centre for available engines at big discounts.
If you go with another Briggs the only thing to watch is the alternator output.
However all Briggs alternators interchange so you might need to swap the stator And perhaps the flywheel ( cant swap between single & twin flywheels ).
A twin will be better than a single just check the dimensions so it will fit.
Other things like exhausts are a bit more difficult as they are part of the mower & not the engine.
Lots of engines at this time of year
I like to buy "pulls" because they are scratched from being fitted so go for a lot less.
A strait engine swap is about a 2 to 3 hour job.
Just make sure you thread the mounting bolt holes before you place the engine otherwise you will need some one to hold the engine and push down on it while you try to force the self tappers in from underneath.
The direct replacement is model 33M777-3036-G5 which is plug and play, you will need to use your muffler. It should be less than 6 bills. You could also short block but that will be more expensive than a complete engine.
