[yuriyo923]

Picked up a free Scotts with 17HP Briggs motor. It was hard to start so I adjusted the valves. After starting, it will run fine for a minute and than starts smoking.. Thinking its the head gasket (or hoping) I took it off but it looks good, or so it seems, I cant find any blow by.. Oil level is good..

What else should I look at?

Thanks

Few images attached.. First is the head and gasket on the gead and rest are of the block!

 

[tomw0]

Did you check the oil level? After sitting for a while, it may have gotten 'energized' with some gasoline added. A high level will enhance smoking.
I will add that some engines will smoke for a while after sitting, and after being put back to work, give up the habit for no apparent reason. I think the rings get loosened up by the lube splashing around along with motion and heat, and finally start to do their job again.
I'd change the oil, and put it to work, but others may have better solutions.
tom

 

[yuriyo923]

Yes I checked the oil level, it's good. The mower has not been sitting for long. The guy I got it from said it had electrical/starting issues. It turned out to be bad PTO switch.

It was hard to crank over so I adjusted valves and after that it seems to have started smoking. There seems to be alot more oil in the push rods galley than what I could remember seeing in other motors, but I dont work on these alot..

 

[rayjay]

Any dirt in the inlet tract ?

 

[yuriyo923]

Nothing noticeable... Before adjusting the valves and when I finally got the engine to run, I did run it with out the air filter or cover for few min.. I'll check again but I'm pretty sure its clean...

 

[Poke]

I spy a carbon trail, bottom right corner of the deck, just above the dowel pin. That may be just a small leak past the head gasket, or it could just be dirt.

How do the cylinder walls look? Rings usually last well on these engines as long as they haven't suffered from dirt ingestion, but if its been sandblasted you may be losing oil past the piston.

The breather valve bears checking, too. If its a fiber disc type on the side of the block, check the disc. If its under the flywheel, be sure the reed isn't stuck or bent open.

 

[yuriyo923]

No that seems to be just leftovers from the gasket. Cylinder walls are smooth, I could not feel any scratches at all. I'll check the breather valve, it's on the side behind the carb. What am I looking for with the breather valve?

 

[Poke]

Mainly just be sure that the large round disc valve moves freely and isn't stuck open. If the valve is stuck open, the engine cannon maintain a vacuum in the crankcase and it will blow oil and/or smoke.

 

[38racing]

Did you check part of head gasket against the block midway between cylinder and galley ? all i have seen blow there and look fine on the head side

 

[yuriyo923]

Checked the gasket, everything seems to be fine... Checked the breather valve, seems to be fine, the large disk moves freely and is not stuck open. Got it all put back to gether started it up and it smokes.. Hoping that it's from the oil in exhaust because its pretty oily from changing the gasket. Will let it run for a while later today and see what happens..

I guess if it does not clear up, rings would be next?

 

[38racing]

You are not supposed to touch that large disc in the breather, just use a feeler gauge around the edge as per briggs manual. You may have damaged it by pushing on the disc.You can make a manometer to check for crankcase pressure.

 

[yuriyo923]

Well go it all back together, pressure washed the motor and muffler to clean all the oil and started her up... Blew some water out of exhaust and smoked for about a minute and cleared up.. Not smoking any more.

I suspect that when I was adjusting the valves LOTS of oil gushed down into the exhaust and I didn't see and I didn't let it all burn up... I think I changed the gasket for nothing but oh well

Thanks for everyone input!