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Got this 10+ year old self propelled mower with B&S engine. Starting this spring it smokes heavily upon starting. Smoke gradually disappears in about 5-10 minutes. Might still be a little smoke then but hard to say given the “grass” I cut; mostly dirt. I’m sure I’ve read about this before and suspect it might be valve seals but not sure. Little help would be very appreciated. TIA. Jerry

Model and type numbers, please.
if it's a flathead engine, they will be stamped on the metal above the spark plug or on the flap above the muffler.

11P902-0693-B1

It either going to be valve seals, or a blown head gasket.
Oil level is good as well?
Start the mower and let it warm up. shut it off, and remove the oil dipstick, look for whisps of smoke coming out of the dipstick tube, that is one tell tale sign of a blown headgasket.

parts lists if you need it

What weight oil have ya been using ?

Scrubcadet10 said:

It either going to be valve seals, or a blown head gasket.
Oil level is good as well?
Start the mower and let it warm up. shut it off, and remove the oil dipstick, look for whisps of smoke coming out of the dipstick tube, that is one tell tale sign of a blown headgasket.

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Oil level fairly good. Have to top it off every 3-4 uses of about 2 hours each

7394 said:

What weight oil have ya been using ?

Click to expand...

30 wt

jerrycmorrow said:

30 wt

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My much older B&S flathead used to use oil too, when I service it, it takes 20 oz of oil (dry), I put in 18 oz of 30 wt, & add 1 oz of STP.
It seems much happier.
And STP is loaded with ZDDP.

Is it the blue smoke of burning oil or is it white smoke indicating fuel? If it's white, install and use a fuel shut-off valve

White

Shutoff valve to be installed this spring

if you're having to add oil and its not making oil (gas+oil), i doubt the shutoff will fix your issue.

Already bought new engine just haven’t installed yet. Gonna try the shutoff valve for a while just to see what impact, if any

I also doubt the that shutoff valve is going to be of any help. Guys just put those inline, as a band aid, when they have a problem with the float seat and needle not shutting off the fuel to the float bowl. You’ve got an OHV engine and from your description I would be checking for a blown head gasket.