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I’ve been fighting a B&S vanguard engine (303447-1188-E1) for far too long. It’s installed in a ball field drag, if that matters - all it does is operate 2 hydraulic pumps via belts - the pumps operate all the attachments and drive system on the ball drag.

What started as an oil change and spark plug replacement has turned into a daily migraine. Plugs were replaced because #2 cylinder was dead and both plugs were severely worn. Cylinder was still dead with the new plug. I checked for spark on both coils and there was no spark at all from #2 - tried adjusting air gap to .008” - still nothing. So I put new coils on it (I’d have to look back at the paperwork - I know they weren’t genuine Briggs coils but I don’t know where my boss found them), air gap set to .010” and then was getting spark from both coils.

Since then, it’s been very picky about starting, and when I finally tried cranking with the air filter off to observe the fuel spray into the Venturi, it was backfiring through the carburetor.

I pulled the covers and inspected the pushrods - they weren’t bent. I adjusted the valves - engine cold (sat overnight) I set the pistons to 1/4” past TDC compression stroke using a dial indicator - adjusted rockers to .005” clearance - and that’s where the frustration really starts. Despite my best efforts, I can’t get the rockers to hold the adjustment while tightening the adjustment nut. Every time I set it, it will inevitably tighten down to less than .005” even though I’m holding the adjuster screw.

Are there any tricks/suggestions for maintaining the clearance adjustment while tightening the nut?

Not too uncommon for this. The lock nut takes up the slack in the threads on the adjuster, a real small amount will show up at the valve tip. Just adjust a couple thousands loose to get the right clearance when all secured. Might rotate the flywheel back and forth while checking the clearance to make sure the cam was on base.

I set the clearance slightly larger so when I do the final tightening they end up where I want them. + or - .001” will work fine.

If you still have it put the working original coil back on and disconnect plug wire from the other cylinder with new coil and see if it backfires in the carb and is still hard to start.

Thanks Tom3 and Rivets. I’d been considering applying a couple drops of yellow thread lock to the adjustment screws and then giving it time to cure before reinserting them into the rockers. I figured that would create enough drag to hold the screw if nothing else. First I’ll try adjusting to .006” and see what I get.

Hammermechanicman said:

If you still have it put the working original coil back on and disconnect plug wire from the other cylinder with new coil and see if it backfires in the carb and is still hard to start.

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Thanks for the suggestion but The original coils are long gone. This ball drag has been in the shop for more than a year now because I’m only working on it as I have time (1-2 hours per month). Since I was getting adequate spark with the new coils I didn’t see the point in keeping the originals. I must admit, however, that I’m not sure what it would suggest from a diagnosis standpoint if I did as you’re describing.

Also can anyone explain why the piston has to be 1/4” past TDC? I haven’t actually measured the valve lift, but visually watching it and holding my hand against the rocker, there doesn’t seem to be any difference in valve lift between TDC and 1/4” past TDC.

1/4” past TDC makes sure your settings are not affected by the compression release.

Gumby83 said:

Thanks Tom3 and Rivets. I’d been considering applying a couple drops of yellow thread lock to the adjustment screws and then giving it time to cure before reinserting them into the rockers. I figured that would create enough drag to hold the screw if nothing else. First I’ll try adjusting to .006” and see what I get.



Thanks for the suggestion but The original coils are long gone. This ball drag has been in the shop for more than a year now because I’m only working on it as I have time (1-2 hours per month). Since I was getting adequate spark with the new coils I didn’t see the point in keeping the originals. I must admit, however, that I’m not sure what it would suggest from a diagnosis standpoint if I did as you’re describing.

Also can anyone explain why the piston has to be 1/4” past TDC? I haven’t actually measured the valve lift, but visually watching it and holding my hand against the rocker, there doesn’t seem to be any difference in valve lift between TDC and 1/4” past TDC.

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The reason i suggested putting in the original coil was because you said you got the non OEM coils form another person. Are you sure they are the correct coils? Did the engine run decent on one cylinder before you put the new coils on? From your first post it sounded like the problem started when you changed plugs and coils.

Thanks again Rivets - my experience with valve adjustment is primarily automotive so I’m used to adjusting them at TDC - I didn’t consider the compression release, so that makes sense. It was easy to find the adjustment procedure online but I didn’t find an explanation as to why.

Hammermechanicman said:

The reason i suggested putting in the original coil was because you said you got the non OEM coils form another person. Are you sure they are the correct coils? Did the engine run decent on one cylinder before you put the new coils on? From your first post it sounded like the problem started when you changed plugs and coils.

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Thanks again - this is why I appreciate forums like this one, because they help provide outside perspective on these things. It was so easy for me to ignore the coils as being responsible because they’re both providing good spark, but that doesn’t necessarily mean they are correct. I remember finding the part number on Brigg’s website, so I’ll make my boss find the receipt and verify if they’re supposed to be the right ones.

It occurred to me also that I could still kind of follow your advice with the new coils. Since the #2 cylinder was originally the dead one, I could just hook the coil to my spark tester so it’s grounded and see if the engine will run on #1 - then vice versa depending on the results.

Also, if anyone was curious, I have checked the compression on a couple different occasions and both cylinders had about 125 PSI (engine cold) so other than adjusting the valve clearance, I don’t suspect (at this point) this is a base mechanical issue, but we’ll see what the valve adjustment and coil tests show first.

Check that the fuel shut off solenoid is working then remove the kill wires from both coils and do a test mow.
The Hall Effect trigger modules can interfear with each other causing bad timing ,
Originally there was a diode in the loom to prevent this then they changed the chip in coils for twins to prevent this happening.
The mounting centres for twins is the same as that for the singles that do not need the modified chip and mowers have come in with 2 brand new cheap single cylinder coils that ran like a hairy goat much as you are describing

Ok, so it turns out that I was wrong about the coils - the ones we installed are the right ones according to the part number I found (591459).

We’re located in what’s becoming a suburb of Des Moines thanks to all the housing that’s being built lately, but most mower and small engine parts aren’t available for direct delivery to us, so when we need model specific parts, we either have to order them online or drive to Des Moines to get them. My boss found his receipt from the supplier and it showed they were Briggs coils matching the part number.

That said, I did get the valve clearances adjusted correctly by starting with .006” so thanks for that. I also attempted grounding one coil through my spark tester and trying to start with 1 active coil - it didn’t start with either cylinder.

Now, who knows their spark plugs? The plugs I originally installed - Champion RN14YC - were supplied by the customer, so I didn’t give them a second thought until today after I verified the coils were right. After crossing the Briggs part number to our [auto parts] supplier, it came back as RC14YC. I didn’t see any obvious differences between them except the size of the hex - 13/16 vs 5/8. Otherwise the heat range and electrode material were the same - but the actual resistance of the plug wasn’t stated. So, I ordered them just to compare the resistance, and if there’s a significant difference, I’ll install them and see what happens.

bertsmobile1 said:

Check that the fuel shut off solenoid is working then remove the kill wires from both coils and do a test mow.
The Hall Effect trigger modules can interfear with each other causing bad timing ,
Originally there was a diode in the loom to prevent this then they changed the chip in coils for twins to prevent this happening.
The mounting centres for twins is the same as that for the singles that do not need the modified chip and mowers have come in with 2 brand new cheap single cylinder coils that ran like a hairy goat much as you are describing

Click to expand...

Thanks for the input. I’ve already verified the fuel shutoff solenoid is functional, and the kill wire for the coils has been unhooked since I started on this thing. I had to chase a few wires when I first started messing with this thing because I’d never heard of the vanguard engines before. I’d have to look again but I don’t think this has a control module - only a regulator/rectifier for the charging voltage.

There is a single kill wire connecting the coils together under the cover, but the connection from the cover to the kill circuit is disconnected (grounds through the ignition switch, maybe? It’s been quite a while since I’ve looked at the diagram or physically traced the wire). Should I remove the wire connecting the coils?

The modules are embedded inside the coil
Remove the wire connecting them together & see how you go .
I don't have the experience to know which engines had an external diode in that wire and which did not so I always pull that wire when diagnosing

Update, sort of....

First, minor correction on the engine serial number, since I don't know if it matters - it's an A1 not an E1 as cited in my first post. I don't know the difference but wanted to clear that up. I have been doing all my research/parts checking using A1.

I haven't had time to do any more troubleshooting since my last post, but I've been digging around in my off time, trying to determine the difference between the recommended spark plugs per the Briggs part# and the plugs that are installed.

Quick recap:

The plugs that are installed in it now (supplied by customer) are Champion RN14YC.
The plugs that it calls for per a cross-reference to the Briggs part #496018S are Champion RC14YC.

Looking at part details on my shop supplier website, as well as a few others, I couldn't find any differences between them except the size of the hex. Then I found this page on Champions website that breaks down their numbering system - https://www.championautoparts.com/Technical/Tech-Tips/decoding-champion-spark-plugs.html - and as it turns out, the hex size is the only difference between them that I can tell. The resistor, electrode, projection, and heat range are all identical.

So I think the next move is to remove the kill wire connecting the coils and see if it makes a difference.

Engine Operators Manual & Illustrated Parts List

OK - so on the last day of the year, with about 1/2 hour left in the working day, I got the cover pulled back off, removed the wire connecting the coils, and attempted to start... and it fired right up! I immediately shut it off, convinced it had to be a fluke, then attempted to start it again...and it fired right up! 2 more times I shut it off and started it without ANY hesitation or problems, even with what had to be some not-so-good gas in it.

As it turns out, 2020 wasn’t a complete loss after all!

So will it harm anything to run it with the kill circuit completely out of the loop? Or should I get a replacement wire with diode? I don’t know how many hours a year this thing will be used but I’m ready for it to leave ASAP.

Personally I would not recommend running the engine without the proper wiring harness. You could very easily ruin a coil. Before ordering a new harness test the old one using the procedure in Sec 2, page 4 of this manual. https://drive.google.com/file/d/0B6NaqjIxWV1ySkZjTTA5TGltZEE/view

Rivets said:

Personally I would not recommend running the engine without the proper wiring harness. You could very easily ruin a coil. Before ordering a new harness test the old one using the procedure in Sec 2, page 4 of this manual. https://drive.google.com/file/d/0B6NaqjIxWV1ySkZjTTA5TGltZEE/view

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I’m of the same opinion but I didn’t know whether or not it would actually harm the coils since (in theory) the only path to ground with the kill wire unhooked would be through the spark plug.

I was also curious if there’s a way to re-wire the kill circuit to eliminate the diodes but haven’t had time to figure it out yet. I’ve converted a couple of customer mowers to a non-module controlled set up using a kit, but those were on Kohler engines. This engine doesn’t have a module but the principle seems like it would be the same.

Thanks for the link. I’ll test the diodes when I have some time to work on it again.

Suggest you disconnect both kill wires at base of each coil. If I understand you correctly, disconnecting where you have does no good.
Walt Conner

Walt 2002 said:

Suggest you disconnect both kill wires at base of each coil. If I understand you correctly, disconnecting where you have does no good.
Walt Conner

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Yes, I’ve already done that and determined the kill wire connecting the coils was the problem - that’s what my post the other day (#14) was about.

What I’m trying to determine now is if there are any other options for wiring the kill circuit besides the diodes.

Just replace the sub loom it is only a couple of bucks
Or if money is tight replace both diodes
A 6 pack is about $ 2
I just got my 100 pack for $ 15 Aus
Normally I would not bother because by the time I cut out the old ones, crimp in the new ons , cover them with 2 layers of heat shrink the labour is worth about $ 30
But the idiot morons who run the Australian B & S warehouse would be mentally challenged trying to run a bush dunny so they never seem have the sub loom in stock and waiting 15 weeks this time of year down here is not on.

bertsmobile1 said:

But the idiot morons who run the Australian B & S warehouse would be mentally challenged trying to run a bush dunny....

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??

The language is a bit different but I totally understand what you mean. I live in the Midwest US but I have an uncle originally from the Brisbane area. Can’t say I’ve ever heard him use the term “bush dunny” before but now I’ll be listening more closely because that is awesome.

I’m not opposed to just replacing the wire harness (certainly not gonna replace just the diodes - not worth my time either) - I just didn’t know if any better options for wiring the kill circuit were available or not.

The only other way to do it is with 2 individual kill wires wired through 2 relays with all of the safety switches acting as the triggers for the relays .
The kill wires pick up signals from the opposite coils so you either have diodes to clamp the ripples or keep the two wires separate till they are grounded to kill the sparks.
There are a few mowers that use relays already to activate the kill circuit .

Thanks - that’s what I wanted to know. The only thing I could think of was to use 2 kill wires with the other end attached to toggle switches that would be grounded when closed. If it were mine, I’d just do it, but I’d better just keep it as is.

Finally got a new kill wire with diodes installed today - also replaced the insulated connector that mounts in the timing cover. The engine started without any problems every time and also shut down when the ignition switch was turned off (previously had to choke it to kill it).

Because it’s been in the shop so long, I put a couple gallons of fresh gas and some seafoam in the tank, then took it outside and drove it around for about 10 minutes and let it idle for about 10 minutes after that. Initially it was spewing white smoke, but that faded after the first 5 minutes.

Then I shut it off while finishing up some other things - it was off for about a 1/2 hour - then it would start, but the white smoke was back and it wouldn’t stay running.

I didn’t have time to look at it after that as the day was over, so I’ll try to check a few things tomorrow.

Thanks again to everyone who’s helped me figure this out.

how much seafoam was in the gas? i think it's 2oz per gallon.

White smoke = oil of some form
Too much snake oil ( seafoam if your like )
Wd 40 or similar
Over full sump
Take your pick

Scrubcadet10 said:

how much seafoam was in the gas? i think it's 2oz per gallon.

Click to expand...

bertsmobile1 said:

White smoke = oil of some form
Too much snake oil ( seafoam if your like )
Wd 40 or similar
Over full sump
Take your pick

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I only put 4 oz in it with about 2.5 gallons fresh gas. Call it snake oil if you like - I’m not saying it’s the greatest product on the shelf, but I’ve found it’s useful in certain situations. Considering this engine has been basically sitting for nearly 2 years (with the exception of the few times I was able to get it started), I expected at least some issues with gum/varnish buildup in the carburetor.

I know it’s not the sump being over full - I verified the oil level was correct before I drove it yesterday.

One thing I’d completely forgotten, is about a year ago, I started thinking it might be an AF mixture problem (partly because it would start with starting fluid), so I started adjusting the mixture screws on the carburetor, but I can’t honestly say I set them back to where they were at any point between then and now.

I started it this morning and let it idle for about 1/2 hour. Unlike yesterday the white smoke didn’t fade, but when I throttled it up to move it, there was a couple seconds of black smoke as well, so I think it would be wise to verify the mixture and adjustment screws on the carburetor are set correctly, then start looking at oil consumption.

Is there a quick way to test the PCV system? In automotive, it can be tested by checking vacuum at the oil dipstick tube, but I wouldn’t be surprised if that doesn’t apply to small engines.

Gumby83 said:

Is there a quick way to test the PCV system? In automotive, it can be tested by checking vacuum at the oil dipstick tube, but I wouldn’t be surprised if that doesn’t apply to small engines.

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Pull the breather line off the air box
Stops smoking = faulty breather or excessive blow by or over full crankcase.
hold a piece of cling wrap loosly over the end of the tube
It should blow then go limp then blow.
You can feel it better if you put your tounge over the end of the tube or a damp finger if you have taste buds adverse to oil .

Agreed. White smoke is burning of engine oil, not a "rich" fuel condition.
I don't think it's Seafoam or WD-40 used during assembly, it's definitely engine oil.

My list...
• Change the crankcase oil to the correct weight and grade
• Make sure engine oil is not over-filled
• Check the engine breather system
• STOP with the excessive idle time. 1/3 throttle OK, but not idle.

Born2Mow said:

Agreed. White smoke is burning of engine oil, not a "rich" fuel condition.
I don't think it's Seafoam or WD-40 used during assembly, it's definitely engine oil.

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FYI
When I post a reply I try to make it as general as possible to cover all bases for the OP and in particular for latter readers looking for answers to similar symptoms.
The OP can look at it & decide which is relevant and what can be dissregarded .
What I omitted was water but I hope most can tell the difference between white smoke & steam coming out the exhaust.

bertsmobile1 said:

Pull the breather line off the air box
Stops smoking = faulty breather or excessive blow by or over full crankcase.
hold a piece of cling wrap loosly over the end of the tube
It should blow then go limp then blow.
You can feel it better if you put your tounge over the end of the tube or a damp finger if you have taste buds adverse to oil .

Click to expand...

Thanks. I didn’t end up having time to testing it today, so I’ll check it ASAP. Maybe I can convince my coworker to put his tongue on the breather tube.

Gumby83 said:

Thanks. I didn’t end up having time to testing it today, so I’ll check it ASAP. Maybe I can convince my coworker to put his tongue on the breather tube.

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While you're at it, tell him to hold the end of the spark plug wire

Born2Mow said:

Agreed. White smoke is burning of engine oil, not a "rich" fuel condition.
I don't think it's Seafoam or WD-40 used during assembly, it's definitely engine oil.

My list...
• Change the crankcase oil to the correct weight and grade
• Make sure engine oil is not over-filled
• Check the engine breather system
• STOP with the excessive idle time. 1/3 throttle OK, but not idle.

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-Exactly where in this thread did you read that I used the wrong oil?
-As I stated in post #26, oil is not overfilled.
-I’ll test the breather next chance I get.

Gumby83 said:

-Exactly where in this thread did you read that I used the wrong oil?

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Calm down. YOU asked for help. I'm trying to "help".
That is my list of POSSIBLE causes.

Born2Mow said:

Calm down. YOU asked for help. I'm trying to "help".
That is my list of POSSIBLE causes.

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You can’t tell me what to do!!!!!

Gumby83 said:

You can’t tell me what to do!!!!!

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Nobody is. They were trying to help you.

First, I'm going to clear the air by offering Born2Mow an apology for my poor choice of words and actions.

I wasn't actually mad or upset about anything. My "angry" response was a poor attempt at starting an argument for my own amusement, because I'm a bit twisted like that. I've always found it curious that someone could read a statement or question on a message board as confrontational, agitating, or otherwise argumentative when there's absolutely no supporting punctuation or imagery to suggest that's the case.

Is that how some people read fiction? With the assumption that every sentence is meant to stab them in the eye when there's no punctuation to support that? I suppose it makes Jules Vern novels much more intense.

Point being, I merely asked a question in response to your post. There were no exclamation points, words in all caps, or emoji's to suggest I was upset or agitated by anything. It was just a question.

So then there was your response, and at the time, I just couldn't help myself but respond like I did. Because I find that kind of s**t funny, and I forget that sometimes people might just be having a bad day and message boards are often the outlet for their frustrations, even if the topic is unrelated. Whether or not that was the case for you, I don't know, but either way, I'm owning my a**holery for my post. I'm sorry.

If you choose to forgive me, thank you - if not, well, that's your choice.

As to the cause of the smoke, it turned out to be diesel contamination in the gas. I'll share the details of how that was discovered in a later post, but it had have been "just the right amount" of contamination for this engine to run on it. I've only seen diesel contamination once - and that was in a pickup - but I've heard plenty of stories and it's rare for a gas engine to run at all when diesel has contaminated the gas. From what I've heard, if they run at all, they sound ready to explode.

Glad you got it figured out!

Ok, so (finally) here’s the story with how diesel ended up in the tank.

As this ball drag had been in the shop for about 2 years, and oftentimes would sit for a month or more between troubleshooting sessions, I would only keep a gallon or less gas in it and frequently drained it if the gas was needed for something else at a moment’s notice.

We have a few gas cans on hand as well as 1 for diesel (yellow as opposed to red so [in theory] no one gets them confused). I can’t prove this happened but what I suspect is someone used an empty gas can to catch old diesel and then the can was later filled without anyone being the wiser.

I figure it was either that or one of the other guys wanted to prank me and dumped some diesel in it without me knowing - but no one took credit so I don’t think that’s the case.

Just change out the spark plugs for glow plugs and it will run fine. ??