Hi all - first time asker...

I have a riding lawn mower with an 18.5 OHV B+S engine... the engine has about 14 hours on it so far (over a few years of low use)... I was running it for a few hours today and noticed some smoke from the engine a couple hours into it. After running the engine under load (mower deck close to the ground), I noticed more blue smoke.

I tried to shut down the engine (turned off the key, throttled down all the way and even got off the mower (with a seat safety switch) and the engine ran for another 30-45 seconds, giving off a heavy blue smoke. After the engine shut down and cooled a bit (seemed to be running hot), I checked the oil and it was still in the OK range (on the low end).

I changed the oil and ran it a bit... blue smoke when throttling down or up and also when under a little load (such as simply in drive on level ground).

Any thoughts on what it could be? Also, any thoughts on the level of difficulty for self-repair (mechanically inclined electrician / machinist but never tried small engines!)

Thanks in advance!

Blue smoke means it is burning oil which means
Piston blown, valve stem seal problems, broken/worn piston rings,
You would have to tear the valve cover/head gaskets down to fix it.

blue smoke means it is burning oil which means
piston blown, valve stem seal problems, broken/worn piston rings,
You would have to tear the valve cover/head gaskets down to fix it.
Could also be a bad breather assembly. Allowing oil to get into the air filter housing.

could also be a bad breather assembly. allowing oil to get into the air filter housing.


Thanks for the answers--- here's one more observation...

I let it run with the air filter cover open and I noticed oil leaking from a part... I'm not sure what this part is, although I'm guessing it's quite a simple thing... My fuel passes through it (downstream of the inline filter) and there is another line that goes around the engine (line - about 1/4" ID rubber hose) (and, of course, a fuel line running from it to the float). This part has a small (about 1/2") round metal screen-like material on it. I'm guessing oil shouldn't drop from here.

Can anyone let me know what this is? It's purpose and could this lead to the blue smoke? (Somehow that oil mixing with the fuel?)

Thanks again -- I ordered repair manuals online, but see they don't cover my engine (18.5 hp OHV Intek plus).

Thanks for the answers--- here's one more observation...

I let it run with the air filter cover open and I noticed oil leaking from a part... I'm not sure what this part is, although I'm guessing it's quite a simple thing... My fuel passes through it (downstream of the inline filter) and there is another line that goes around the engine (line - about 1/4" ID rubber hose) (and, of course, a fuel line running from it to the float). This part has a small (about 1/2") round metal screen-like material on it. I'm guessing oil shouldn't drop from here.

Can anyone let me know what this is? It's purpose and could this lead to the blue smoke? (Somehow that oil mixing with the fuel?)

Thanks again -- I ordered repair manuals online, but see they don't cover my engine (18.5 hp OHV Intek plus).


Okay in that case it most likely is what mowerman is saying
I am not all that familiar with lawnmowers but it could be the breather or a filter

Okay in that case it most likely is what mowerman is saying
I am not all that familiar with lawnmowers but it could be the breather or a filter


Thanks for your input! I can only hope, as this would seem like a much easier repair!