1968Commando 163 #1 Posted July 10 (edited) Hey all, I cut the grass the other night and noticed smoke pouring out the front of the motor then went to turn off the engine and it self ignited it’s self a few times and puffed smoke out a bit from the exhaust, anyways it looks like the smokes coming out the breather but I don’t know there is no oil coming from it though I rebuilt the motor on this tractor but in all honesty I’m thinking it’s time to retire it, the old 36 inch rear discharge deck is worn out bad and needs alot of work it still cuts fine but it’s just old and needed alot of work cosmeticly the tractor is nice and mechanical the motor is good no oil burning but to keep cutting grass it’s too old probably time for a zero turn considering I cut 6 yards with it already Edited July 10 by 1968Commando Share this post Link to post Share on other sites
Retired Wrencher 5,766 #2 Posted July 10 68Commando: I would keep it for sunny day cold beer ride around the hose. They are savable. 1 Share this post Link to post Share on other sites
kpinnc 14,573 #3 Posted July 10 (edited) I would also check the oil for a smell like fuel. If it does, change it before running again. The engine would have to get way overheated for oil to ignite if it keeps from the breather otherwise. These old engines can be rebuilt for much less than replacement and it will run another 40 years. You won't get such longevity with any engine currently manufactured. Edited July 10 by kpinnc 2 Share this post Link to post Share on other sites
1968Commando 163 #4 Posted July 11 22 hours ago, kpinnc said: I would also check the oil for a smell like fuel. If it does, change it before running again. The engine would have to get way overheated for oil to ignite if it keeps from the breather otherwise. These old engines can be rebuilt for much less than replacement and it will run another 40 years. You won't get such longevity with any engine currently manufactured. Well here’s the thing I just did rebuild the motor this winter all new rings, and stuff, but it started smoking out the breather vent, is it overheating or is it just not something to worry about being it’s 60 years okd Share this post Link to post Share on other sites
1968Commando 163 #5 Posted July 11 On 7/10/2025 at 5:12 AM, Retired Wrencher said: 68Commando: I would keep it for sunny day cold beer ride around the hose. They are savable. Thank you Share this post Link to post Share on other sites
wallfish 18,060 #6 Posted July 11 2 minutes ago, 1968Commando said: Well here’s the thing I just did rebuild the motor this winter all new rings, and stuff, but it started smoking out the breather vent, is it overheating or is it just not something to worry about being it’s 60 years okd Breathing smoke and fire is definitely something to worry about. What exactly "self ignited"? That smoke vapor from the breather? Did you ever check if the oil smells like gas? Fuel can enter the engine case through the fuel pump if the diaphragm has a hole or cracked. Is that a brand new fuel pump or new diaphragm? Share this post Link to post Share on other sites
kpinnc 14,573 #7 Posted July 11 1 hour ago, 1968Commando said: Well here’s the thing I just did rebuild the motor this winter all new rings, and stuff, but it started smoking out the breather vent, is it overheating or is it just not something to worry about being it’s 60 years okd Something is definitely wrong if it is doing that after being rebuilt. 60 years old isn't part of the problem anymore. Share this post Link to post Share on other sites
adsm08 3,144 #8 Posted July 11 2 hours ago, 1968Commando said: Well here’s the thing I just did rebuild the motor this winter all new rings, and stuff, but it started smoking out the breather vent, is it overheating or is it just not something to worry about being it’s 60 years okd Proper machining of the bore? New rings don't seal well to old, glazed cylinder walls. Share this post Link to post Share on other sites
1968Commando 163 #9 Posted July 12 4 hours ago, adsm08 said: Proper machining of the bore? New rings don't seal well to old, glazed cylinder walls. Well could be. I put in 10 over rings and never honed the cylinder all I did was put new rings on it…that might of been the problem, I plan to buy a zero turn so all this tractor will be is a sentimental piece of equipment I’ll get out to stretch its legs after that purchase Share this post Link to post Share on other sites
1968Commando 163 #10 Posted July 12 6 hours ago, wallfish said: Breathing smoke and fire is definitely something to worry about. What exactly "self ignited"? That smoke vapor from the breather? Did you ever check if the oil smells like gas? Fuel can enter the engine case through the fuel pump if the diaphragm has a hole or cracked. Is that a brand new fuel pump or new diaphragm? No the engine will pop and sputter when you shut it down if it’s been run at wide open throttle for some time Share this post Link to post Share on other sites
1968Commando 163 #11 Posted July 12 6 hours ago, wallfish said: Breathing smoke and fire is definitely something to worry about. What exactly "self ignited"? That smoke vapor from the breather? Did you ever check if the oil smells like gas? Fuel can enter the engine case through the fuel pump if the diaphragm has a hole or cracked. Is that a brand new fuel pump or new diaphragm? No fuel in gas Share this post Link to post Share on other sites
adsm08 3,144 #12 Posted July 12 10 hours ago, 1968Commando said: I put in 10 over rings and never honed the cylinder Even if you don't hone it you should at least run some sand paper over it by hand to break the glaze. Share this post Link to post Share on other sites
AHS 1,537 #13 Posted July 12 On 7/10/2025 at 5:37 PM, kpinnc said: I would also check the oil for a smell like fuel. If it does, change it before running again. The engine would have to get way overheated for oil to ignite if it keeps from the breather otherwise. These old engines can be rebuilt for much less than replacement and it will run another 40 years. You won't get such longevity with any engine currently manufactured. He’s 100% correct!! Share this post Link to post Share on other sites
1968Commando 163 #14 Posted July 13 13 hours ago, adsm08 said: Even if you don't hone it you should at least run some sand paper over it by hand to break the glaze. Well alright then we’ll look into that I guess. Share this post Link to post Share on other sites
