Hi,

I have a 2 year old craftsman lt3000 lawn tractor with a 20hp briggs 1 cylinder ohv intek plus engine. My son (of course!) was mowing a couple of weeks ago and "it just died", reportedly with no noise or warning. I got it to barely run this weekend and immediately noticed a loud popping from the air cleaner, put my hand down there and exhaust was coming back out of the intake to the air cleaner. Pulled the valve cover off, cranked it over, and noticed the intake valve operated normally but the exhaust valve only partially opened and only once every 4-6 times it should have. Turns out that the exhaust valve adjuster nut had worked loose and backed off so far that the exhaust valve woudn't compress as it should. I tried setting the valve lash at .06 and .08 for intake and exhaust but only got about 1/2 of normal engine speed at full throttle. Increased the gap to about 16 and 18, and it ran fine. Mowed for about 10-15 minutes with no problems and then all of a sudden saw a huge puff of oil smoke, seemed to be coming from the muffler but it's under the front of the tractor so hard to tell for sure. Shut it down immediately and cranked back up with blades disengaged and ran fine. Oil level is good and mowed again today for about 15-20 minutes, then again got a huge puff of smoke and tried to stall but disengaged the blades and ran fine again, so rode it back to the house with no
Problem. As I pulled up to the house, I decided to try pulling the dipstick while it was running and had a good amount of pressure and spat oil drops out of the tube. Obviously, something's wrong, and I don't want to just mow in 10 minute intervals to avoid the smoke problem! I'm not familiar with this engine and would normally assume the valve adjuster failure may have blown the head gasket due to nowhere for the exhaust to go but I also hear there is a pressure valve of some type in the dipstick tube, so don't want to jump the gun; and I don't know what else may cause the oil smoke after running that long. I also don't understand why doubling the valve lash made it run better? Does anyone know more about these engines, and can give some advice? Also, is the valve lash supposed to be .06 & .08 cold, and at tdc or 1/4" past tdc, on these engines? Are there any download-able service manuals available anywhere?

Beware Mow4play!! I have a 2008 Craftsman with the 20 ohv intek plus motor. We never had any issues with this tractor or motor until May 2001 (3 months off warranty). My husband was out mowing and the motor seized up! We took to the shop where a Briggs & Stratton rep came and looked at the motor. The crankshaft was bent and the casing for pistons (I think, I'm no mechanic) was not only broken into 3 pieces, but there were also cracks visible. We purchased from Sears and also purchased the snowblower, weights and the cab enclosure to the sum of like $2,700.
Anyway, The B&S rep stated his conclusion was that we not only ran the motor out of oil but continued to run it that way, however, the oil in the motor was clean. I searched the model # of my motor and to my amazement I found about 23 pages of forum complaints on this motor from slight oil leaks to smoking to seizure of the motor. Most complaints ranged from 2-3 years after purchasing new, which is also the time frame for our motor that took a dump.
The customer service from Sears & Craftsman was so rude and unprofessional, I would never advise anyone to purchase a thing from Sears or a mower bearing the Craftsman name. Good Luck!