Help with carburetor please

[you tube mechanic]

Ok, so the saga continues with a new problem. New carburetor has arrived and installed on 5/12/20, changed spark plug again also due to the other one looked fouled from the fuel flooding issue. Tractor started right up with a little choke input. run great, drove it down the street 100 yds or so and back. no issues, continued this process for 3 more days with no issues. Went to deliver mower to owner, started up, drove it over to her house about 1/4 mile away, just as I was turning on her street it sputtered a little and popped out a small cloud of white smoke from the exhaust, then pulling in driveway it sputtered like it was dying and produced a massive white smoke cloud that I couldn't see thru. Both times engine recovered and continued to run. Shut it off and we talked awhile, started it several times in her presence and now it backfires nearly every time but starts and runs if I understand the function of the shutoff solenoid it should not backfire. I asked her to mow with it for the next week or so and let me know what it is doing. I am at a loss of what else could be causing this new problem. I made no adjustments on the new carb, figured it was tested before they sent it. Please advise if you can. (I did check the solenoid before installing new carb with a 9v battery, I could hear it actuating). Thanks for any and all help.

 

[bertsmobile1]

New problem will be a blown head gasket
Run it for a while , turn it off then pull the dip sick
White smoke coming out of he tube confirms a blown head gasket.
Just a coincidence designed to make you look silly.

 

[you tube mechanic]

Ok, head gasket may be next, I will check the dip stick. Please educate me a little about small engines. A blown head gasket on a car/truck is allowing coolant to enter pistons/etc. producing constant white smoke out the tail pipe. Minus coolant on a Briggs & Stratton (air cooled) how does the engine oil get into the piston area? Is the head jacketed/have ports that oil runs thru similar to coolant running through engine block to cool automotive engine? Also the lawn mower is not producing a steady stream of white smoke, it only did it when it sputtered the 2 times, almost like it farted a cloud of smoke. I have seen some videos that say if engine it smoking out the exhaust then it's a stuck fuel float and fuel is getting in the oil reservoir, but with a brand new carb I think that is unlikely but not impossible.

 

[The Chairman]

There are no oil passages in a briggs and stratton engine that I know of. White or bluish white smoke is probably oil consumption. Is the crankcase overfilled? There are seals on the valves and they're easy to replace. Is this an UHV or OHV???

 

[you tube mechanic]

Thanks Chairman, it is a 18.5 hp OHV briggs and stratton.

 

[StarTech]

Sounds like you have a 310000 series Briggs engine. On this engine series the head gasket is bad to blow between the cylinder and the pus rod galley. This cause compression gases to enter the crankcase which vented the PCV system into the carburetor. Then the engine burns the oil. I have seen to excessive amounts of oil and not even smoke.

If you have access to an leak down tester, remove the valve cover and dipstick. As you apply the test air pressure to the cylinder at TDC compression stroke. IF the head gasket blown the escape air sound will louder at the push rod galley when compared the dipstick tube.

There are no oil passages in a briggs and stratton engine that I know of. White or bluish white smoke is probably oil consumption. Is the crankcase overfilled? There are seals on the valves and they're easy to replace. Is this an UHV or OHV???

What is UHV? Is this the L-head (side valve) engines?

 

[The Chairman]

Under head valves as opposed to over head valves. The former have lower compression ratios and ergo, less power.

 

[StarTech]

Then the correct term is L-head when referring the Briggs engines as all the service manuals for those engines are so labeled.

 

[The Chairman]

Then the correct term is L-head when referring the Briggs engines as all the service manuals for those engines are so labeled.

Good for you! Not every manufacturer uses that term. When I grew up we often called them flat heads, but when we got corrected by the guys who had a different term we started referting to them as under head valves, for that is what they are. I've also heard them referred to as "valves in block".

 

[ProMower]

You did the right thing, buy a new carb for $28 and be done with it, many more years of reliability without the problems.