6.75 hp B&S blowing white smoke randomly, oil level fine.

Hi,
I was very pleased to find an active forum where people can get help with small engine repair! Looking forward to trouble shooting my mower problems with you!

I have a Snapper 21” walk behind with a 6.75hp B&S engine that my dad bought a while back and over the years it has become very hard to start and the self-propelled system stopped working and so he replaced it years ago and just the other day I bought it off his hands for 50 bucks to mow the yard at my newly purchased home! I only know a little about small engines, the type of stuff you could expect someone who has been mowing all their life to know- but I’m handy with a socket set, and I’m confident enough to be dangerous :smile:
Here is the problem I’m wanting help with:
When I start the mower, it runs clean for a little while and then begins to blow white smoke, then it will run clean for a little while then blow white smoke, (wash rinse and repeat) This seems random and sometimes it will run for quite some time with smoking hardly any noticeably smoke at all and then randomly belches out a ton. and then clears completely up again. strange.
I’ve replaced the air filter, replaced the spark plug, and drained the oil filling with new oil- and NOT over filling. I know white smoke is usually an indication of too much oil- been there before many times.

I would love to hear your thoughts on it, I'm willing to try anything and I would like to see if its something I can fix on my own before calling a repair man. If you need any additional information such as model number for engine or mower, let me know.

Lets start with the model, type and code from the engine, so we can see what you are working on. too many engine designs to just throw out random info.

I apologize for the delay, I've been out of town and didn't have access to internet.
the model number for the motor as it appears on the engine: 126602 0118 E1 030402
Mower model number : P2167517BV
part number 84862

Thanks!

Not trying to thread hi-jack, but I came here looking for advice with the exact same problem as the OP. Mine is an older 4hp flat head, not OHV. Mine is also not an oil overfill or oil type issue. Will start smoking white/blue after running a few minutes, then stop, then smoke, then stop, etc etc.

What I can add is that the engine will change pitch, either revving slightly higher or lower before it starts to smoke. FYI I did replace the carb diaphragm & gasket before this started.


my info Model 10A902 Type 2252 E1 Code 98040955

White smoke = oil burning
On a flat head oil entering the cylinder can only come past the rings or through the breather.
SO either new rings or clean / replace breather .
Occasionally you get a bit through the inlet valve stem.

Picked up a new breather today, will install tomorrow and report back. Hopefully this will solve my, and the OP`s issue.
Anything else to check that doesn't involve removing the head?

Many thanks for the help and suggestions

Replaced breather, still smokes as before. :frown:

Guess I'm pulling the head. I'm still unsure why this engine smokes intermittently if its the rings or head gasket.

Its a flat head.
There is no oil above the head
There is no push rod tube to connect the combustion chamber so no way fro a blown head gasket to allow oil into the engine.
Pull the breather of the connection to the carb and stick a length of tube on it 2' of garden hose will work well.
If the mower stops smoking, the rings are gone.

I'd like to thank you for taking the time to offer help. It's truly appreciated.

I tried your suggestion with the hose, and unfortunately it made no difference.

If there is any other thoughts or suggestions, I'm all ears. Just as an fyi. This mower was not smoking at all until the following services were performed.

Oil and air filter change.
Spark plug change
Governor springs replaced
Carb cleaned
Carb diaphragm, gasket, pick-up tube replaced
Breather assembly replaced after hitting forum.