Briggs Vanguard HELP!

[jinman]

I think you have a fuel feed problem and running with the choke on is increasing intake vacuum so much that you are sucking oil past seals and maybe the piston rings too. I would get a small poly squeeze bottle with a nozzle cap. Fill it with gasoline so that as you squeeze a tiny flow comes out. Remove the air filter and spray a little gas inside to get the engine started. When it starts, squirt the smallest stream possible into the throat of the carb and see if you can keep the engine running without the choke closed. If you can, your carb definitely has a clog in one of the jets or maybe the main fuel passage into the carb venturi. By choking, you are drawing fuel from from some source other than the normal flow.

Once I had a similar problem and the carb was drawing fuel up around the screw that held the breather/filter on. If I tightened it down, it would die. If I loosened the filter screw, the engine would run.

I think ethanol in your fuel is likely the problem. We used to be able to leave fuel in the tank and carb bowl over winter, but with the new fuel and ethanol added, it just seems to clog things up much quicker.

 

[Jerry/MT]

I have started this thread in another section already but I think its better suited here so if a mod wants to delete the other one please do so.
I have a 16 horse power Briggs Vanguard V twin over head valve #303447. This engine has about 3000 hours on it and has run great for the past 2999 and has been very well maintained all its life. Recently it lost power and started blowing blue/black smoke out the exhaust. This condition has gotten MUCH worse, its smoking so much now that it fills a three car garage in under a minute. It now only runs under full choke and has little to no power.
I then replaced the carb with a new one, new plugs sparking fine, oil changed, two new head gaskets, fully inspected heads and valves, compression checked out to about 110 psi on each cylinder cold, air filter good and clean, new intake manifold gaskets, new fuel pump.
After doing all this the engine STILL does the exact same thing. Only starts up and runs with full choke at 50% throttle or more, smokes like crazy, and still has no power.
HELP ME PLEASE.

If you have that kind of compression, it's not the valves, etc. Your rings have lost oil control, your crankcase is over filled or possibly you have a clogged crankcase vent. The oil control rings could be worn, stuck or broken. It's possible the valve guides are worn and the intake vakve seals are shot but that doen't just suddenly happen.
You might try running it for a check with the oil fill cap off(if it's one of those that sits high above the cranckcase and see what happens. If you see alot of blowby there, it could indicate a clogged crankcase vent or worn rings. It's hard to make an exact diagnosis from this far away but ythe compression you are reading certainly says the valves are sealing and the compression rings seem good.

 

[KubotaSam]

Some Briggs and Stratton engines have plastic lobes and gears on the camshaft. They can slip on the metal center of the shaft and throw the valve timing off. I have no idea if your engine is built this way or not. I bought a leaf vacuum that would not run and the gear on the camshaft had slipped.

 

[Mark Page]

If you got 3,000 hours out of a Briggs Engine consider yourself lucky. Just replace it with a Kawasaki or Honda. Try Northern Tools

 

[subergoo]

ok guys got some new developments, with the MUFFLER OFF I sarted the engine up, and like before It needed full choke and about 50% throttle and smoked heavly for only a minute or two, then the smoking almost completely stopped. At this point I slowly took the choke out little by little until it was off completely then I messed with the throttle going from full to idle and eveything in between. Still no smoke and the engine seemed to be running happily with a slightly rough idle and heavy backfireing when ever throttle was quickly reduced. I decided to take the machine out for a test drive and it did pretty well, seemed to be lacking a little bit of power and would die under heavy sudden load but would start right back up.
I investigated the muffler closely and foud some cracks on the back side of it and after banging on for a while I managed to get about a 1/4 cup of what looked like rusty carbon out of it, some chunks but mostly powder. at this point nothing else is coming out of the muffler and I dont hear anything rattleing around inside it.
So after letting the engine cool COMPLETELY I crossed my fingers and tried starting it up. But it did the same thing, needed full choke and 50% throttle to run until it hit operating temp, only then could I dump the choke and play with the throttle, however the smoking seems to have stopped for the most part, I would say its atleast 90% better but smokes significantly more on cranking start up and when shutting down.
At this point Ive got an engine with no muffler, that needs to be choked till it warms up, doesn't handle sudden load well at all, moderate all around power loss, smokes a little bit, and back fires when throttle is reduced quickly.
Who wants to take a stab at it now??? ALL input is welcome

Thank you all again for taking the time to help a stranger out, if more people were more like you all in there day to day lives the world would be a better place.

 

[subergoo]

If you got 3,000 hours out of a Briggs Engine consider yourself lucky. Just replace it with a Kawasaki or Honda. Try Northern Tools

Hey now, I know every one has a brand they love and a few that they hate, but Ill stand by my Briggs, Ive got about 8 in my fleet of equipment all in the 16 HP range, 2 of em have 3000 hours 1 has 3800 hours, Ive even got one on with 4500 hours and its never been rebuilt

 

[SHORT KID]

I would dump a can of SEA-FOAM in that tank then just let it run. You will probably have to readjust the carb if it has adjustmemts on it. You could first check the fuel tank and drain it and add fresh fuel before the SEA-FOAM.

 

[tcartwri]

ok guys got some new developments, with the MUFFLER OFF I sarted the engine up, and like before It needed full choke and about 50% throttle and smoked heavly for only a minute or two, then the smoking almost completely stopped. At this point I slowly took the choke out little by little until it was off completely then I messed with the throttle going from full to idle and eveything in between. Still no smoke and the engine seemed to be running happily with a slightly rough idle and heavy backfireing when ever throttle was quickly reduced. I decided to take the machine out for a test drive and it did pretty well, seemed to be lacking a little bit of power and would die under heavy sudden load but would start right back up.
I investigated the muffler closely and foud some cracks on the back side of it and after banging on for a while I managed to get about a 1/4 cup of what looked like rusty carbon out of it, some chunks but mostly powder. at this point nothing else is coming out of the muffler and I dont hear anything rattleing around inside it.
So after letting the engine cool COMPLETELY I crossed my fingers and tried starting it up. But it did the same thing, needed full choke and 50% throttle to run until it hit operating temp, only then could I dump the choke and play with the throttle, however the smoking seems to have stopped for the most part, I would say its atleast 90% better but smokes significantly more on cranking start up and when shutting down.
At this point Ive got an engine with no muffler, that needs to be choked till it warms up, doesn't handle sudden load well at all, moderate all around power loss, smokes a little bit, and back fires when throttle is reduced quickly.
Who wants to take a stab at it now??? ALL input is welcome

Thank you all again for taking the time to help a stranger out, if more people were more like you all in there day to day lives the world would be a better place.

The valves in these motors will stick under certain conditions when the guide is failing. If it's the intake valve it will cause severe reversion through the carb. It looks just like a fuel related problem. Heavy black smoke, and backfiring.

Since your not willing to pull the valve covers and look, start it again with a helper and put a gloved finger on each exhaust tube. The cyl that's acting up will be cold.

 

[subergoo]

Tim...I checked the valves, rockers, springs, guides, and rods when I pulled the heads to change the head gaskets, and it all looked good. Or are you suggesting that I pull the valve covers off while the engine is running?

 

[tcartwri]

You will need the engine covers on for it to run. The fuel pump runs on crankcase pressure. Actually it will run for a minute or so with the fuel in the bowl. So yes, you could do that.

A visual inspection might rule out a valvetrain problem. These engines are known for stuck valves, loose valve guides, loose valve seats, and bent pushrods. A few google searches will show you what to look for.

The valves can stick when cold or hot. Sometimes you can feel the interferance by just operating the valve with your thumb.

Mine did the same thing twice. Was running perfect, and then went pig rich and lost all power. Like you I thought it was a fuel problem.