Export thread

I have a 23hp twin vanguard B and S engine with 170 hours. Had to replace the head gasket. Put head back together and set the valves. Ran for 30 seconds or so backfired, and died. Did this 4-5 times. Readjusted the valves and it ran ok. Put the shroud back on the engine and now it will not hit at all. I have fire on plugs (used inline spark tester), compression test shows 120 on both cylinders, and plugs have gas on them. I have used new plugs and new mags. Thought the backfire might have messed up timing so I took case apart. Gears lined up perfectly and flywheel key is in place. Also replaced key switch. Any thoughts or ideas? Thanks

Why did you replace head gasket at 170 hrs.? Procedure you used to adjust valves?

My model number is 386777-0111E if that helps anyone.

Left cylinder was leaking oil on exhaust. Thought it was coming out of the valve cover but it was head gasket with a piece blown out. Did both of them while I had it apart.

Take your valve covers off and make sure each valve opens and closes, meaning, that they open fully and close fully.

Would anyone know the part number for the carb rebuild kit for this engine? Engine is 386777-0111e.
Is there an aftermarket carb that I could just pick up for it?

Jloven14 said:

Is there an aftermarket carb that I could just pick up for it?

Click to expand...

Of course, there are several after-market carbs you can pick up.
Will they help you or be better than what you already have is the question.

Ok, I think I may have found the problem. The fuel solenoid on my carb seems to be acting up. When the engine was in the mower, I heard a click on when I turned the key on and I thought that was the solenoid working. I took the carb off today and removed the solenoid. Connected it to a 12v power source and nothing. Simply got warm but no movement at all and no click. Part 842109.
Is there any alternative to this part? Looks like $170 if its even in stock anywhere. Found the entire carb for $200 online. Seems like there would be a cheaper solenoid somewhere.

Get a small bolt the same thread pitch as the solenoid. Or keep the solenoid and snip off the plunger. Cost is free and will never fail on you again.

Caveat is you use/close an inline fuel shutoff valve one minute prior to you finishing mowing. Cost for this valve is a few bucks. Should be using one anyway on every mower that can fit one.

slomo said:

Get a small bolt the same thread pitch as the solenoid. Or keep the solenoid and snip off the plunger. Cost is free and will never fail on you again.

Caveat is you use/close an inline fuel shutoff valve one minute prior to you finishing mowing. Cost for this valve is a few bucks. Should be using one anyway on every mower that can fit one.

Click to expand...

this^ (snipping is the easiest versus deleting the solenoid)

leaking oil and smoking oil out of the exhaust is not likely a result of a failed head gasket. What I mean is that burned oil coming from the exhaust it usually caused by piston ring blow by...and that can be caused from bad/worn rings, damaged/scored cylinder bore, worn or stepped valve guides/seats. It can also be caused by oil overfill! another condition is a too rich fuel condition. or spark plug gap is not correct.

so a few questions and recommendations:

when you removed head cylinder to replace head cylinder gasket did you inspect the valve guide and check to make sure the valve seats did not step out? did you clean the valves, lap the valve and seats, and clean up the piston top, combustion chamber and inspect for any cylinder wall scores or pitting? This is the standard practice in the big 300 hour service or when you remove the cylinder head...these are things you want to do anytime you have the cylinder head removed....since you have the cylinder head off ...did you check and make sure oil is not overfilled?

if you don't want to remove the cylinder head again, you can do a leak down test...this will tell you lots of things...where the leak down test is failing...or if it is failing at all. If you get leaks pressuring the crank case (crack the oil filler cap off slightly and listen), then it's going to be piston blow by...(bad rings, cylinder or piston damage). If it leaks from exhaust, it's exhaust valve(S) leaking. If it leaks back OUT from the carb, then it's intake valve(S) leaking. There are many videos on youtube showing how to do a proper leak down test. you can rent the gear from nearly any auto store (deposit returned when you return) a leak down test takes a bit of experience and nuance to perform correctly. For instance...you will ALWAYS get some leaks...especially for piston blowby (it's never going to be a perfect seal (be design). It's noticing large leaks that matters. for valve leaks however, there should be NONE. Make sure you are AT TOP DEAD CENTER AND not in the automatic decompression PHASE of rotation. This takes a little practice to notice where that is in rotation. Make sure you have the valve covers off and notice in rotation when BOTH valves are fully shut is the best way to avoid getting fooled into thinking you have a valve problem.

Jloven14 said:

Ok, I think I may have found the problem. The fuel solenoid on my carb seems to be acting up. When the engine was in the mower, I heard a click on when I turned the key on and I thought that was the solenoid working. I took the carb off today and removed the solenoid. Connected it to a 12v power source and nothing. Simply got warm but no movement at all and no click. Part 842109.
Is there any alternative to this part? Looks like $170 if its even in stock anywhere. Found the entire carb for $200 online. Seems like there would be a cheaper solenoid somewhere.

Click to expand...

The quickest and easiest test for this is to remove the solenoid and hold your finger on the bottom of the carburetor ball and see if your running problem goes away.
You've already had advice on the quick way to fix it or the little bit harder way on sourcing a short plug of the right threads that will fit in there and seal it off.
A bunch of used carburetors is the best place to source One of these from because when you end up at a parts store looking for something like this the typical drain plugs are too big and the bolts that have the right pitch which is probably somewhere around a metric 8 fine thread, are too long so that's why it's the harder way to do it.
You can get a nut but you'll need a fairly thin one and thread it on and then you can cut off the bolt to the proper length and then take the nut back off to clean up the threads but that's far harder than just snipping off the plunger tip.
Most of these have a pointed pencil plunger but some have a rubber tip.
I've seen a handful of the rubber tips get loose because they become hard and they will vibrate up on the shaft and cause irregular running problems but receipt themselves when the key turns off and the plunger snaps close pushing the rubber back on to the shaft.
Then, it will restart and run fine for a few seconds to maybe a couple of minutes and then repeat the process.
On these, there are ways that I have found that work well to rebond the rubber to the shaft or you can just take the rubber tip off and it will work just fine which is basically the same as snipping off the metal.

With mowing season behind me, I took a couple months off from this problem engine. Started back on it a couple of days ago. Let me recap as I am still having no success.
B & S 386777-0111E is the model. 168 hours total time. Original problem was a blown head gasket.

Replaced the blown gasket along with the one on the other cylinder head. Cleaned up the piston and other parts. Replaced the plugs and magnetos. Put all back together. Engine would start, run for 30 seconds or so, backfire and quit. Did this 5-6 times. Adjusted valve clearance and checked mags for proper clearance.
After that, engine would not fire at all. Took it to a shop who kept for 4 weeks and could not fix (Don't think they looked at it more than 5 min).
Got it back and replaced the backfire fuel solenoid. Thought for sure this was the problem since the old one would not move with 12v applied. Still will not fire at all.
Was suggested that the engine was out of time. Took the case off and verified timing mark was lined up perfectly. Replaced cover using new gaskets and filled with oil.
Removed the flywheel, key was intact and all was lined up correctly.
Lastly, I swapped the carb out with one on a running duplicate engine, thinking that might be the problem. Still will not hit at all.

I have fire on both plugs (tested with inline testers), compression is good on both cylinders (per the shop), valves seem to be working properly, so I am at a loss as what else it could be. The fact that it will not even try to start makes me think I am not getting any fire on the plugs, but when I remove one and hold it against the engine, I get plenty of fire off of them.
I hate to send this engine to the landfill, but I am out of ideas as to what else it might be. Anyone think of anything else to try?

I had a mower that quit running, and I discovered that the fuel line before the filter was plugged with spider eggs. Pressured the gas tank, and it shot out. How that danged thing got in there is beyond me. That's very rare and unusual, but apparently I'm the exception.

Jloven14 said:

Ok, I think I may have found the problem. The fuel solenoid on my carb seems to be acting up. When the engine was in the mower, I heard a click on when I turned the key on and I thought that was the solenoid working. I took the carb off today and removed the solenoid. Connected it to a 12v power source and nothing. Simply got warm but no movement at all and no click. Part 842109.
Is there any alternative to this part? Looks like $170 if its even in stock anywhere. Found the entire carb for $200 online. Seems like there would be a cheaper solenoid somewhere.

Click to expand...

I know lots of people use the 9 volt power source, but really this is unnecessary and it can create an illusion of failure. Just use the mower battery!. In this way, you are using the same circuit and battery source it will be using in normal operation (fewer things introduced as possible faults). And then do the test. So just remove the anti back fire solenoid from the carb bowl. Keep it connected to the wiring connector. Insert ignition key and turn from OFF TO RUN (NOT START!). From OFF TO RUN, the ignition switch will send 12 volt power to the antiback fire solenoid circuit (which happens to also be the same safety switch circuit...pay attention to what I just wrote !!!! and think about this). What you should SEE is that the anti backfire solenoid pin should retract back into the body of the solenoid Without power, it remains popped out (effectively sealing against the main fuel jet within the carb). If it does not retract, then turn key back to OFF and with your finger try to depress the pin. Sometimes these pins get corroded with old fuel and gunk and even can have rust withing. If you cannot excercise the pin back into the body, then squirt from wd-40 on that sucker and let it soak...then depress it again. push with the plastic handle of a screw driver if it's really stuck. Does this over and over several times until it freely depresses and pops back up on it's own. if it does not depress or is really hard or will not pop back up, then it WILL NOT MATTER IF THE IGNITION SWITCH is sending power to the device. These damned anti backfire solenoids are notoriously poorly designed and they fail all the time. You have some options. 1 - you replace it and roll the dice that it fails again...it will over time...guaranteed...how soon, who knows..but these will never last. it's a design problem that you just cannot overcome. or 2 - you snip the end of that pin off with side cutters so it is near flat flush cut at the solenoid body. This effectively deletes the problem out of your engine system. You will still install the device and screw it back into the bowl, because that is what holds the bowl in place and you will still hook it up to the connector, because without it, the ignition START will never happen (again, it's part of the safety switch circuit! see I told you this was going to be important..more on this below). if you are concerned with a back fire, just idle down and let the engine cool for a few moments before you turn key to off. In most cases, a properly tuned and timed engine is not going to back fire. (exposing another reason why an anti back fire solenoid is not a very good design...it can actually conceal a poorly tuner carb, air leaks, faulty valves and out of time conditions and even a crappy spark plugs. If you understand how this anti back fire solenoid can hide those performance issues, you are probably starting to get the gist of my recommendation: delete this damned inferior device from your system, even IF it is working.

last note: sometimes a safety switch that is not operating (brake pedal does not depress a swtich, or seat does not depress a switch, or blade engagement lever does not depress a switch, or PTO/take off linkage does not depress a switch can cause some to assume the anti back fire solenoid is faulty. So first make sure all your safety switches ARE WORKING before you make that assumption. You can temporarily bypass safety switches for purposes of troubleshooting. I will not go into detail how to accomplish that..there are literally dozens of youtube videos showing how to. Caution: I DO NOT recommend permanently deleted or bypassing safety switches. Even if YOU are very knowledgeable and safe, you must also understand that someone else might not understand what you have done and if they operate this machine without the safety switches very bad things can happen, really quick. So just be smart and keep your safety switches working and operating. The ONLY reason to bypass them would be to troubleshoot as I explained.

Good luck. you got this!

I suggest you purchase Manual above for guidance.
See Vanguard V-Twin OHV Repair Manual above.

Jloven14 said:

Replaced the blown gasket along with the one on the other cylinder head.

Click to expand...

When changing the head gasket. did you lap the block head gasket surface and the head? I've never seen one come off, and be flat or near flat. YMMV.

Bertsmobile knows a guy that can make solid core copper head gaskets. Think holy grail of gaskets.

I use Permatex hi-tack spray sealant on most all gaskets. RTV is a thing of the past.

Jloven14 said:

With mowing season behind me, I took a couple months off from this problem engine. Started back on it a couple of days ago. Let me recap as I am still having no success.
B & S 386777-0111E is the model. 168 hours total time. Original problem was a blown head gasket.

Replaced the blown gasket along with the one on the other cylinder head. Cleaned up the piston and other parts. Replaced the plugs and magnetos. Put all back together. Engine would start, run for 30 seconds or so, backfire and quit. Did this 5-6 times. Adjusted valve clearance and checked mags for proper clearance.
After that, engine would not fire at all. Took it to a shop who kept for 4 weeks and could not fix (Don't think they looked at it more than 5 min).
Got it back and replaced the backfire fuel solenoid. Thought for sure this was the problem since the old one would not move with 12v applied. Still will not fire at all.
Was suggested that the engine was out of time. Took the case off and verified timing mark was lined up perfectly. Replaced cover using new gaskets and filled with oil.
Removed the flywheel, key was intact and all was lined up correctly.
Lastly, I swapped the carb out with one on a running duplicate engine, thinking that might be the problem. Still will not hit at all.

I have fire on both plugs (tested with inline testers), compression is good on both cylinders (per the shop), valves seem to be working properly, so I am at a loss as what else it could be. The fact that it will not even try to start makes me think I am not getting any fire on the plugs, but when I remove one and hold it against the engine, I get plenty of fire off of them.
I hate to send this engine to the landfill, but I am out of ideas as to what else it might be. Anyone think of anything else to try?

Click to expand...

Are you taking a can of spray carb cleaner and spraying it for 2 to 3 seconds into the intake and then cranking it with the choke open but engine to full running speed??
This is the only way to check one hand the first thing you should do when a mower comes in that cranks but won't start.
You have verified that the engine timing is correct from the camshaft etc and that the flywheel key is good and if you have spark then the only thing left is fuel and or valve problems which could be from valves not seaing but unlikely and could also be from a bad camshaft for the love twist on their spline shafts which many of these engines have.
Both of these are far less common than just not getting fuel through the carb so give it fuel by a can of spray carb cleaner.
It's either going to run or it's going to wet the plug so badly that they will foul out.

OK, I will try spraying some carb cleaner in the intake and let you know if that works.

I’m gave up on this project and took it to a mechanic friend last week. He noticed that the entire flywheel seemed to be magnetized. I checked on another mower engine and that’s obviously not the case. Is that normal for the B&s vanguard engine? What would cause that to happen? Should I get a new flywheel?

Jloven14 said:

I’m gave up on this project and took it to a mechanic friend last week. He noticed that the entire flywheel seemed to be magnetized. I checked on another mower engine and that’s obviously not the case. Is that normal for the B&s vanguard engine? What would cause that to happen? Should I get a new flywheel?

Click to expand...

No! It sounds like this guy is a car mechanic friend and not a lawn mower tech.
Unfortunately auto mechanics often do a lot more harm than good on the small engines because they're simply too different.
While I have heard of some odd things happening to the magnets on a flywheel that wasn't physical damage, because that's far more likely than anything else, from reverse polarization to demagnetization or weird things like that, I have NEVER seen one of these things happen for myself so I really don't believe most of the stories I've heard!
I have been running a shop commercially for 14 years now and have seen thousands upon thousands of mowers and these small engines.
While lots of things are possible.. most of these weird things are not very probable or likely at all.
And 99.8 or maybe more like 99.3% of the times, it will be something else rather than some crazy thing that it might be.
Most of the time if you start with the basic troubleshooting procedure, and if that's a good one because many people don't do it well or do it in a lousy order etc, you will rule out many other potential problems as you go and along the path quite quickly diagnose what the problem is.

In this situation, anytime you have concern about ignition, which should be the second thing you do and not the first... it's usually enough just to pull out the spark plug or two when it's a twin, and stick them back in the wires and ground the base of them to the block and crank it over to see if there's consistent spark going spark spark spark spark spark spark.
That rules out over 90% of the ignition problems including flywheels, coils, kill switches, magnets, igniters ...

However, you shouldn't be there first because it's often a waste of time.
The first thing to do, every time when you have a small engine that won't run , after you check the oil to make sure there's enough in there to safely start it and after you've determined that it will crank over at normal speed on its own or that you can pull the rope...is to give it an external fuel source.
This means dribbling a little bit of gas into the intake hole feeding the carburetor or spraying some carb cleaner in there or -if you must- I'm starting fluid but I highly discourage it because it is really rough on engines and just not necessary.
On a riding mower size engine, you spray a 2-second blast into the intake from the carb cleaner can and leave the choke in the open position if it has a manual choke which would be 3/4 on many throttle controls and not pushed all the way up.
Then you crank it for five or six seconds to see if it will run on its own for a couple of seconds.
If it doesn't do it the first time you repeat the spray of about 1 to 2 seconds and recrank.
It's also okay to do it a third time but if it doesn't run by the third time stop giving it the spray first. Now simply crank it over for 8 or 10 seconds with the choke open to see if it will try to run.
Probably at least 70 or 80% of the time when you do this, they will take off and run for 2 or 3 seconds.
Anytime this happens you can pretty much guarantee it's not getting fuel or feeding it on its own and it's usually the Jets and the carburetor are clogged up but it can also be ABS (solenoid) on the bottom of the carb, fuel pump if it has one, blockage in the gas tank or the fuel line or even a damaged and internally collapsed fuel line.
But the key point is if it runs for even a couple of seconds on your carb spray you have ruled out all kill switches, most ignition problems, and most valve train problems.
I have to say most because if it's a twin you could still have a bad coil or valve train problems on one head and it could be running on one cylinder.

Only if it doesn't do anything differently when you give it a fuel source do you start to check ignition and get into other things.

The most efficient diagnostic procedure is check the fuel delivery and give external fuel first.
Then check for ignition and consistent spark at each plug.
Then move on to removing the valve covers and check into the valve train.

Jloven14 said:

I’m gave up on this project and took it to a mechanic friend last week. He noticed that the entire flywheel seemed to be magnetized. I checked on another mower engine and that’s obviously not the case. Is that normal for the B&s vanguard engine? What would cause that to happen? Should I get a new flywheel?

Click to expand...

The flywheel could give the illusion that the entire flywheel is magnetized is because the center of the flywheel is covered by magnets. Because they produce the magnetic field to generate output to the stator and regulator to recharge the battery.

Well problem finally solved. Turns out I had a bad wire connecting the magnetos together. I tried replacing the wire with a regular piece of wire, didn’t catch there was a diode in the original. Ordered the wire from B and S, engine started really after a few seconds. Also had a bad fuel backfire solenoid. Cut the tip off and reinstalled.

Boy I love those that clip off those solenoid as I end up replacing mufflers that end needing replacing.

And those are cheap to make up when you the diodes, wire, terminals, and terminal splices along with correct crimper. Btw there is two diodes in that harness, one for each coil.