# Nothing major



## Shade Tree Wrench (Mar 3, 2014)

I haven't been on here, lately, so mainly saying Hi. 

My Bolens 1668 (1988?) has continued to drive me crazy. The engine (Briggs 16 HP twin) has had a mind of it's own, (gremlin) that I couldn't resolve. It would run great for awhile, then drop about 400 RPM and sound like it was struggling, then start to pop and/or backfire through the carburetor. When it was running properly, some times, when I engaged the mower/PTO, the RPM would drop and then recover and, at other times it would go into the struggle mode. Finally, I gave up and took it to the tractor hospital (shop), where it's still being cared for. I found that I'd be taking the better part of a day to remove a bunch of sheet metal, etc. to get to a part to check/work on, only, to find that my efforts had no effect. After putting in many frustrating days, I realized that I was in over my head and beyond my frustration tolerance and took it to the pros. Hopefully, they'll be able to perform the exorcism, successfully.

With all of your, most appreciated and helpful ideas, in the past, I tried rebuilding the carburetor and then checked the valves. One exhaust valve was tight...good compression but 0 clearance for the feeler. I removed that valve and ground it (low speed wet grinder) to specification. Nothing fixed the problem. 

I called to see how things were going several days ago and was told that it was done. They had drained and flushed out the fuel tank and cleaned out the fuel system. This worried me because I had done this myself, several times. When I went to pick it up, I asked if I could test drive it? They told me to "have at it". I drove it around at different speeds for 15-20 minutes, turned it off and restarted it, throttled down and then back up and, then, mowed their lawn! Once again, the gremlin was showing it's ugly, little head. Fortunately, it did it's bad, in front of the mechanic and the owner. Unfortunately, the mechanic was unhappy that they had told me that it was ready because he wasn't done yet...GRRR. He told me that he was waiting for a new air cleaner and that the engine would do all of these things if you run it without one. This sounds, a little, strange to me but, obviously, what do I know? If this is the case, this engine has a, very sensitive, personality. I'll let you know how it's running once she's "discharged".
Jim


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## jhngardner367 (Apr 5, 2011)

My 18hp Briggs twin did this. I found out it had bad sparkplug wires from the armatures.Coils were good,but wires arced to ground,causing bad running/stalling,etc.
I replaced the wires by digging them out of the towers,and using epoxy to hold new ones in.


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## Shade Tree Wrench (Mar 3, 2014)

Thank you for the advice. I'll check the wires out if the shop fix doesn't work. I picked her up last Friday and things seem to be, pretty, good. The engine likes a, nice, 2 minute warm-up (I do too), when I advance the throttle to full power, it still struggles a bit but as long as I advance slowly (this seems to be the governor...governing), no backfire and when I turn on the PTO solenoid for the mower, no more problems. That is, as far as I can tell...On Saturday I was, merrily, cutting the grass, when I had to turn the tractor off to move some things. When I went to re-start, that lousy plastic gear on the starter, stripped...again! I had, only been running it for around 20 minutes, so, I haven't had the chance to see if it's, really, fixed.
I keep a spare starter and I have a several spare gears, so having the repair part isn't a problem. I, just didn't have the time to do the R&R. It takes me around 2 hours, on a good day, to remove some of the sheet metal, unbolt some of the motor mounts and then lift the engine enough to get at the starter. So, I finished with my Ariens walk behind. 
Why, on Earth, did Briggs decide to switch to the aluminum flywheel, when they knew that they would have to make the starter gear out of something softer...and, why this soft? These things look like they're made out of recycled milk bottles! I imagine that both answers are the same...money. They, probably, saved a whole $2 per engine...and gained alot of bad will, in the process.
I'm thinking about trying to make a gear that has the teeth made out of linen bakelite, that I can mount onto the plastic gears hub. The bakelite is softer than the aluminum but much tougher than the plastic. This might seem to be too much work, but I can do it in my spare time and if/when this gear strips, I can do the R&R...for the last(?) time.
Jim


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## jhngardner367 (Apr 5, 2011)

From the first,these engines had a problem of "kick-back",once in a while,or the starter gear would "hang",and the result was a ruined starter,or damaged engine.
It was much cheaper to replace the gear(or ring-gear),than the starter or an engine.
If the engines were made with a distributor,and variable timing,you wold probably never have these problems.
But that would make them heavier,more complex,and much more expensive.
So,most use a static timing system,which actually favors higher RPMs,but still lets it idle well.


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## Shade Tree Wrench (Mar 3, 2014)

Yea, I understand the concept of, "sacrificing" the cheapest part. It's, just, so frustrating when you have to spend several hours fixing something, knowing that you'll have to do it again and again. Especially, when the manufacturer redesigned the engine (steel flywheel to aluminum), causing this problem. I have other, older, Briggs engines with the steel components and, yes, I'll get a backfire/kick back, every now and then, but the starter gear doesn't get destroyed. The older engines are, much, more forgiving...though I do love CDI! Actually, I have considered trying to adapt an old, Delco, starter generator, just for starting...or if the alternator goes south, wire it in for charging. Tearing the engine down to replace the windings, would not be fun.

In my, "sordid" past, I've worked in mechanical design/engineering. Just for giggles(?), I'm going to see if I can find a comparable gear made from a linen phenolic resin (bakelite). I have been able "reverse engineer" most of the dimensions. The one giving me trouble is determining the pressure angle. Often, the part you want, already, exists on a shelf, somewhere. The "devil" is in finding it. While Briggs, most likely, had these made for them, I imagine that the same gear does exist using a, more, robust material.

If I find a source, I'll be sure to post it here.

Thanks again,
Jim


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## Shade Tree Wrench (Mar 3, 2014)

I got caught up in getting my beasts ready for this winter and failed to update my success(?) So far, I haven't found a phenolic resin gear to replace the plastic one, so I used the plastic and will keep my fingers crossed. The "good news"...I did the R&R in an hour, this time! Practice does, indeed, make perfect(?). 

Here's how I did it. Disconnect PTO belt, remove sheet metal covering the starter, unbolt 2 front and the left rear motor mounts, using a come-along, slowly, lift engine until there's enough clearance for the starter (while this strained the right rear mount more than I like, it survived. Bolens used thru bolts, on the mounts with the heads on the bottom and loosening the right rear, is all but impossible. It's buried inside part of the frame & cannot be, reasonably accessed, with a wrench. When loosening the top nut, the whole bolt turns. Some day, yea right! I'd like to "kluge" a work-around for this.). Once I have the clearance, I do the swap. I, did, find that I was cutting my fingers on the edge of the rear engine sheet metal when R&Ring the back bolt with a standard 1/2" wrench and have bought an extra long one, just for this job. $10 to avoid bloodshed is good.

Anyhow, so far so good. When I crank the engine, it no longer has any problem with backfires...except if I try to restart it immediately after shutting it down, after prolonged use. Several times it did backfire but if I let it cool off for around 5 minutes, before restarting, it's okay. Initial cold starting I set full choke and 1/4 throttle. Then, slowly, back off on the choke and let it warm up, at 1/4 throttle for around 5 minutes. It doesn't like to low idle when it's cold. 

The shop was emphatic that I use additives in the gas. Around here, the Chicago area, I guess we have a problem with water in the gas. I may be going overboard...but better safe than sorry. I make a cocktail. In a 1 pint can of Sea Foam, I add 1 oz. of Star-tron enzyme treatment and 1 oz. of Briggs gas water treatment. Then I mix this cocktail with my gas at a rate of 1oz. per gallon. As I said, so far, so good.

Now, it's all ready for winter. My "project" adaptation of a Deere 316 dual hydraulic plow...with joystick...weight box and grooved and siped tires, is waiting for the first, ugly, snowfall...or not! A sunny and warm winter wouldn't bother me in the least!

I'll post a picture of it once I get a new camera. Funny, my old 35mm camera lasted 30 years. My Fugi digital lasted 2 and can't be fixed...it's obsolete! Go figger...

Jim


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## jhngardner367 (Apr 5, 2011)

Sounds good,Jim!
A couple of tips: First,get some REAL chamois,about 12" square. When you fill your tank,poke the chamois in far enough to make a "well",about 2" deep,and slowly pour in the fuel.The chamois will let the fuel in,but not the water. Wring it out,when done,and let it dry.

Second,on the camera,go to Walmart,or even best buy and get one of the little digitals for around $100. Some have 5x zoom,and 16 megapixel lens. It's what I have,and they're great !


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## GTcollector (Dec 27, 2010)

I have serious doubts your problem can be "fixed" without a overhaul/valve job. First a little background. The material in the stater gear is not the issue. It is easy to blame that though because it seems irrational that an engine part could be built of plastic like material, but I assure you those plastic starter gears can last as long as any metal gears. Briggs would not have used that design otherwise, they are in the business of building a quality product and in doing so much time and engineering went into these products, back to the issue. When a starter gear is being stripped it means that the engine is out of time, most often caused by a valve issue. If the valves are bad, or the engine is out of time, the first thing that happens is the engine becomes harder to start, the battery doesn't last very long due to strain, it burns up the starter due to overload, and in turn ruins the starter gear, after a while especially during long hot use it will heat up and warp the valves, burn up the rings and eventually ruin the engine. The engine is a air cooled engine and when the exhaust valve opens late, or not long enough, heat does not dissipate causing internal engine damage. I'm afraid your engine could have been run long enough in this condition to effect its operation to the point that a "tune-up" or some tinkering may not fix it, but rest assured it is not the fault of the plastic starter gear or the aluminum flywheel. Many people get a mower from a previous owner that hasn't properly maintained it or the P. O. didn't know how to maintain it and some problems can't be undone. Those engines are just like our own bodies, that while they can take a lot of abuse and still run, it does effect performance, hence medications for blood pressure, cholesterol, and boner pills. It is a testament to the quality of your engine that it is still running at all.


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## Shade Tree Wrench (Mar 3, 2014)

Thank you for your thoughts. I had rebuilt the carburetor and checked the valves, earlier this year. One exhaust valve was very tight (a .001 wouldn't slide in, but the compression was good) so I ground it to spec. Still, it wouldn't run properly (backfiring, and dropping power when a load was added without an RPM recovery). I ended up taking it to a shop that has an excellent reputation. (I used to teach shop and taught basic small engine repair.) They found that the fuel had water in it, even though it was, only a week old. I hadn't realized that there's a problem with the quality of gasoline around here and water is common. They added a secondary filter and, emphatically, recommended a Briggs fuel additive, which I am now using.

The engine starts and runs, much, better now. It has set of "rules" and, if I follow them, so far, I'm satisfied with it's performance. It has to have a good 3-5 minute, cold start, warm-up. After it's been run, for awhile if I shut it down, I need to wait a couple of minutes, before starting; otherwise, it will, occasionally, backfire. They, also, told me that they have found these Briggs engines to be, somewhat, temperamental, particularly regarding fuel/fuel supply. I'm guessing that the warm-up is necessary because, since fuel supply is critical, a warm engine improves vaporization in the cylinder.

As far as the starter gear goes, I have a DC electric shop that I've used for over 30 years to rebuild all for my starters and alternators. He rebuilds so many of these starters that he buys the replacement gears in boxes of 100. Some of his customers need a rebuild twice a year! One backfire, on start up, can destroy the gear. While backfiring is a sign of some other problem, personally I still, feel that the gear is too weak, especially, since the starter is, so, hard to get to. 

Particularly with this engine, I've found that it's affected by weather changes, quite a bit and that, occasionally, I have to tweak the carburetor as the weather changes. Often, the warning is a backfire. I have another tractor, a 1974 MTD 900 (gear drive) with a Briggs 16 HP one lung, cast iron that starts and runs great and doesn't have weather issues. 

Thank you, again, for your reply. It's so good to have this forum, to bounce "puzzlers" around with each other...those of us in the minority...who believe in taking care of our machines, either by ourselves or having routine maintenance/repair performed at a quality shop. Far too many people buy a lawn mower at a "big box", do nothing but add gas and, occasionally (perhaps) sharpen or replace the blade. Then, after several years, when it starts giving them trouble, they put it on the curb and buy a new one. The good news for us is we have a huge supply of decent machines, I call them "roadkills" available to us. The same applies to cars...100K miles is just "broken in".

Jim


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## GTcollector (Dec 27, 2010)

Shade Tree Wrench said:


> Thank you for your thoughts. I had rebuilt the carburetor and checked the valves, earlier this year. One exhaust valve was very tight (a .001 wouldn't slide in, but the compression was good) so I ground it to spec. Still, it wouldn't run properly (backfiring, and dropping power when a load was added without an RPM recovery). I ended up taking it to a shop that has an excellent reputation. (I used to teach shop and taught basic small engine repair.) They found that the fuel had water in it, even though it was, only a week old. I hadn't realized that there's a problem with the quality of gasoline around here and water is common. They added a secondary filter and, emphatically, recommended a Briggs fuel additive, which I am now using.
> 
> The engine starts and runs, much, better now. It has set of "rules" and, if I follow them, so far, I'm satisfied with it's performance. It has to have a good 3-5 minute, cold start, warm-up. After it's been run, for awhile if I shut it down, I need to wait a couple of minutes, before starting; otherwise, it will, occasionally, backfire. They, also, told me that they have found these Briggs engines to be, somewhat, temperamental, particularly regarding fuel/fuel supply. I'm guessing that the warm-up is necessary because, since fuel supply is critical, a warm engine improves vaporization in the cylinder.
> 
> ...


It's good to have someone as thorough and knowledgeable as you are around here. Trying to diagnose a problem a foot away is tough, trying to do it from halfway around the country and by email is even tougher. We should always remember gas, air and spark first. I only use non ethanol premium and check for water or ethanol before dumping it in, not hard with the little test kit. I've heard of station owners running a water hose into the fuel tanks to "stretch profits, lovely huh.


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## skunkhome (Nov 30, 2008)

Years ago when I was in college I worked at a full service station. When we "sticked" the tanks there was a piece of "gum" that looked like silly putty on the tip of the stick that would turn red if there was enough water to be in danger of entering the pickup tube. If it was red we would call the supplier and they would either pump the bottom of the tank of add a dryer. At certain times of the year condensation was a big problem. I never pump gas at a station where a truck is dumping a load and stirring up the tanks.


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## jhngardner367 (Apr 5, 2011)

Same here. I managed a Tulsa Oil full- service station,for 7 years.and we were only allowed to have up to 300 gallons of water in the tanks,before they had to be pumped.
Ethanol only worsens the moisture problems,and today's fuel only has a shelf life of 90-100 days !


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## Hoodoo Valley (Nov 14, 2006)

skunkhome said:


> I never pump gas at a station where a truck is dumping a load and stirring up the tanks.


That's a very good point.


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## Hoodoo Valley (Nov 14, 2006)

Gosh, I remember one of the first jobs I ever had was working in a full service gas station, pumping gas, washing windshields and checking oils. It was an Exxon and I had the uniform and station attendant hat. Man, I'm feeling old you know that? :lmao: I'm actually very young though


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## jhngardner367 (Apr 5, 2011)

I had a 2 yr old Yamaha 650 Maxim given to me,many years ago,because the guy couldn't get it running,nor did the dealer.
He had topped off the tank,while a drop was being made.
Seems the dealer,and he,never remembered the "kiss" rule=Keep It Simple, Stupid !
The tank had 99% water,in it !
He told me that the guy in front of him,had just topped off a motorhome,and when it died,the guy had it towed,and they found the water problem.
I ended up going in to court,on their lawsuit. They both won damages/loss costs.


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