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Discussion Starter · #1 ·
Hello I am hoping to pick the board's collective brain as to what could be happening to my 95 Lawn Boy Silver Series 2 cycle mower...

Here is what it does...I will go out some days, prime it once or twice, crank it once or twice and it runs perfectly as long as I need it to.

Other days, same routine, but it won't crank for anything and after several pulls and a couple more primes, I smell gas like it is flooded. I let it sit for 4-5 hours and come back, crank it and it starts perfectly...

I have replaced the float and spring mechanism on it last year to stop the fuel leaking out of the carb, but this started last year about this time.

I am sure you can picture someone all ready to mow, cranking on the mower for a while until thoroughly pi**ed off and then giving up only to have the mower crank right up a few hours later...

Anyone have any ideas?

Thanks a bunch in advance.

Matt
 

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Have you cleaned the carborator thoroghly? I can't help you a whole lot with this, but carborators are the common culprit that cause many small engine problems like this.

Also, welcome to the forum!
 

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Discussion Starter · #3 ·
Forgot to mention, it seems like it isn't getting any spark when it does this.... possible intermittent problem with the kill switch???
 

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Discussion Starter · #4 ·
Have you cleaned the carborator thoroghly? I can't help you a whole lot with this, but carborators are the common culprit that cause many small engine problems like this.

Also, welcome to the forum!
Nope, have never cleaned it as it runs perfectly when it starts so I didn't think it could be something as simple as that. Any easy suggestions on cleaning without disassembling? Brake/carb cleaner spray?

I am truly a novice on small engines and my first attempt was changing the float mechanism to stop the leaks from the carb....

I truly love Lawnboys and this is a $5 replacement from a pawnshop for an older one. They didn't have gas in it and said they didn't know if it ran or not. Put gas in it 3 years ago and away I went...

So I am willing to put a little money into this as I feel it is a better mower than most new ones out there...

thanks.
 

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Have you swapped out the spark plug yet?

A fresh plug can fix some strange symptoms especially on 2-cycles. ;)
 

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Discussion Starter · #6 ·
Have you swapped out the spark plug yet?

A fresh plug can fix some strange symptoms especially on 2-cycles. ;)
not yet, but that will be first thing tomorrow.. cleaned filter today and removed exhaust cover and cleaned out some of the carbon but it was still pretty encrusted. Any ideas as to a good easy cleaner?

Would spray carb cleaner damage it in any way?

Thanks for all the help.
 

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That buildup can be nasty to remove for sure. I generally use a wire brush and scrape it out of mufflers.

Carb cleaner on the muffler itself would probably be fine. I have mixed feelings though if you are thinking about spraying it directly into the exhaust port to loosen deposts there.
 

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I suspect you have an ignition coil going bad on your engine. Way to common all Lawn Boys. Works one time and then not the next. Roger
 

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Good suggestion on the ignition coil. What is common among LawnBoy folks is to remove the coil, wrap loosely in tin foil, and bake in an oven for an hour at 200 degrees. This will occasionally bake out moisture and make the coil good again. Worth a try!
 

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Discussion Starter · #10 ·
Ok, I finally gave up and took it to a shop and of course it started right up. After going over it the service guy came to the conclusion that some amount of gas must be leaking into the engine just enough to basically keep it primed. When I was priming it, it was putting too much gas into the carb and flooding it. He suggested not priming it at all and just trying to start it each time. Tried it for the last two days and after 3-4 cranks it has started each time. So apparently at this point, I can only figure that even a prime or two was enough to flood it...

Thanks to everyone for their help and suggestions.

With that said, I think I have caught the bug because I bought another Lawnboy off Craigslist two days ago, a 4 cycle, model 10212 with a 5.5 Tecumseh engine for $15.
I figure it is either a 96 or 97 based on the model and pictures (the SN is unreadable).

With that said, after priming it 2-3 times, it cranks on the first or second try each time. The problem is that it seems to smoke quite a bit. I checked the oil as I read here that overfilling can be a problem. Took it in to have it checked out and the service guy said that it could have a bad gasket/seal in the engine that is allowing a little oil to leak and cause the smoke.

When running it is runs fine but then the motor drops down a bit and the smoke comes out, then after 30 seconds, the motor speeds back up and the smoke drops off quite a bit. The engine doesn't bog down or anything, but you can hear a slight change down right before the white smoke starts...

My question to you guys is if this sounds reasonable and if this is something that I can fix myself? The service guy said it would cost too much for him to take it down and replace the gaskets/seals ($200-300) due to labor costs, but he said it was something I could do myself as the gaskets/seals were fairly inexpensive.

So is this something I could do myself? I am handy with most mechanical things and am willing to try if it isn't something that would inadvertently destroy the mower.

As usual, I appreciate any suggestions/advice from everyone.
 

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Might be a piston ring problem too. Hard for us to say as you know your mechanical ability better then we do as far as if it is something you can do. ;)
 

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Discussion Starter · #12 ·
Ok, I guess I wasn't very clear in what I was asking... I meant is there any specialized tools I would need and if there is an "Idiots Guide to Replacing Gaskets and Rings" or some step by step service manual so I don't end up with a pile of parts and can't figure out how to get them back together?

Thanks.

And as an aside...I talked to a guy today with a Lawnboy "Scamp" with a white top and a kind of hourglass shaped handlebars who said it runs really strong for $40. Said he inherited it from his dad and didn't need two mowers.... Any thoughts on whether it would be worth it? I can't figure out how to attach a picture....
 

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Some websites you might find useful for reference: ;)

http://www.tecumsehpower.com/

https://support.lawnboy.com/portal/server.pt/community/lawn_boy/216

Notes on the Troubleshooting and Repair of small Gasoline Engines and Rotary Lawn Mowers

Snip from last link:

Tools and supplies

While you probably did not purchase your lawn mower specifically for the joys of repairing it, there is always a chance that despite all your precautions, the blade will strike a rock that just happened to grow out of the ground when you weren't looking. Therefore, it makes sense to be prepared. Basic servicing of small engines doesn't require a $500 tool caddy. However, some basic hand tools and other items will be needed.

  • A good quality set of socket wrenches is essential. For small engine work, a 3/8" ratchet and a set of sockets from 1/4" to 1" as well as a special spark plug socket. Usually a deep 13/16" type - check for your particular engine(s) will suffice. A basic set from Sears (Craftsman) should be fine and will come with a lifetime replacement warranty as well! If you have never invested in a socket set, now is the time. Forget about those $4 specials, however, as they are generally worse than useless. A word to the wise: you really must have a socket set to do any kind of work on small engines. Slip-joint pliers or worse yet - ViseGrips(tm) - just will not do!
    While open-end or box-end (closed) wrenches may be used for certain bolts, some simply are not accessible without a properly sized socket (like cylinder head bolts).
  • An impact wrench may come in handy for removing those really stuck bolts and screws. These accept standard screwdriver bits and sockets (via an adapter) and convert a hammer blow to rotary motion. First try penetrating oil like Liquid Wrench(tm) and normal tools though.
  • A variety of good quality screwdrivers - both straight and philips.
  • Needlenose and utility pliers.
  • Wire cutters and strippers.
  • Ball-peen hammer or other metal hammer.
  • Rubber mallet.
  • Funnel, drain pan, plastic milk jug for used oil. These can be discards from the kitchen.
  • Old rags, cotton swabs, paper towels, etc. for cleaning. An old but soft paint brush for getting dust and dirt our of various places.
  • Wood blocks for propping things up or securing the blade or flywheel when loosening or tightening. Other drift (scraps) of wood and soft metal.
  • Torque wrench. An adequate model that will work with your 3/8" sockets can be purchased for around $10. Setting the torque - tightness - on certain engine bolts is critical to proper operation and long life.
  • Feeler gauge - a set of precise thickness strips or wires for setting spark plug and point gaps. The .020" and .030" sizes should suffice for basic maintenance.
  • Flywheel puller - build or buy. See the sections starting with: Flywheel removal. If purchased, it must be one designed for your model engine, not just something you picked up in the hardware store marked 'flywheel puller'! Briggs and Stratton, Tecumseh, and others sell tools specifically for their engines. This is the easiest way to remove the flywheel.
  • Carburetor cleaner - this comes in a spray can. It is also probably as flammable as gasoline, toxic, and will eat plastics and painted surfaces. Therefore, use only in a well ventilated area or outdoors and take appropriate precautions.
  • A tube of thread-lock comes in handy as well as some anti-seize compound like graphite grease for the muffler/exhaust bolts and spark plug.

For most of the procedures described below, the basic set of items listed in the section: Tools and supplies will suffice. However, some of the following more specialized tools may be needed depending on how far you go:

  • Micrometer - many of the measurements of wear to engine parts requires determining the diameter of shafts or bearing surfaces. Except for the piston, most of these can be accommodated by a micrometer with a maximum opening of 1 to 1-1/4 inches. However, in many cases, what is important is not actual diameter but clearance - and this can be determined with the inexpensive 'plastigauge' or a substitute.
  • Plastigauge - these are disposable pieces of calibrated plastic used to determine the critical clearance between the rod bearing and crank pin journal. You place one in between the rod bearing and crank pin journal and tighten to specifications. When removed, simple measurements on the markings on the squashed plastigauge will very precisely determine the clearance, taper, and out-of-round specifications for your bearing. It is also possible to obtain most of this information by using slips of paper or foil of known thickness but this will not be as accurate or convenient.
  • Flatness gauge - a good machined straight-edge and a set of feeler gauges will suffice for checking the mating surfaces of the cylinder and head.
  • Ridge reamer - the 1/8" or so above where the piston slides in the cylinder will develop a buildup of carbon. In addition, if the engine has seen really heavy use, the metal in this area will be higher (less worn) than the section below. In order to remove the piston, this ridge must be eliminated or else it either won't come out or you risk breaking the rings. Fortunately, the metal ridge is rarely a problem on lawn mower engines and the carbon ridge can be removed with a simple homemade tool which is just a soft metal (i.e., aluminum or brass) piece with a straight edge or inside right angle. You probably will not need an expensive commercial ridge reamer tool. You will not need one at all unless you will be removing the piston.
  • Piston ring compressor - when reinstalling the piston and rings, it is virtually impossible to squeeze the rings together to fit into the cylinder without some help. Commercial piston ring compressors are available for about $5 or you can make your own from a large hose clamp and strip of sheet steel (say, 1" x 12" x .020"). This tool is not needed unless the piston is being removed from the cylinder.
  • Piston ring expander - this allows the easy removal of piston rings from the piston. With care, you can do this by grabbing the two sections of the ring and guiding it off the piston by hand. In any case, unless you will actually be removing the rings from the piston, this tool will not needed.
  • Valve spring compressor - in order to remove and reinstall the valves, their rather powerful spring must be squeezed together tightly. This is almost impossible to do without this tool. I have done it with an improvised clamp designed for holding lab equipment but it was barely up to the task and not fun. However, unless you are going to remove the valves, this tool will not be needed.
  • Rubber mallet - the engine overhauler's 'persuader'. In particular, to break free the crankcase/oil sump joint and for reinstalling the piston using the piston ring compressor. A small one will be more than enough.
  • Scrapers - to remove built up carbon deposits and stuck gasket material - start with a strip of aluminum. For stubborn deposits, a flat edge paint scraper or straight blade screwdriver will come in handy. Take care not to scratch any machined surfaces. Coarse steel wool can then be used to finish up after the major deposits have been removed. For fine work, an X-acto knife also is useful.
  • Wood blocks (4" x 4" x 8" typical) for supporting the engine on your workbench.
  • Rags, paper towels, and more rags. Just make sure to dispose of oil soaked material safely. Plenty of old newspaper to protect the ground or table top.
To attach a picture there are a couple of ways to do it. First way is after you click reply and the next screen comes up, scroll down and click the manage attachments button. From there you can upload the photo from your computer. If it's to big of a file you might have to reduce it's size using a photo editing program. Or you can send me a personal message I will give you my email address and you can send the photo to me and I can resize it for you. :)

Second way is to have an online photo storage accout with PhotoBucket (the one I use) or Flicker, etc. Those places give you a link after you upload the photo that you insert in the post to make it show up.
 

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I'm wondering what gaskets/seals he was talking about. Maybe the head gasket? Do you recall his mentioning those? Don't think this will be too big of a deal, personally. You might just want to take it apart and look for a place that has oil residue/carbon buildup from the burnt oil.
 

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Discussion Starter · #15 ·
Once I think about it, he probably said it was the rings. But he was just guessing based on the fact that it was smoking. He didn't take it apart to examine it. So if I break it down, I will probably replace all the gaskets and rings at the same time just to be sure.

I think I can figure out the gaskets based on the exploded diagrams I found on LB website. But I am wondering how tough it will be to replace the rings? Do you just pull them out and put the new ones in? Or is there some type of calibration?

I mean these are basically just washers like in a faucet, right? Except they keep the oil from leaking rather than water...
 

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Discussion Starter · #16 ·
Good Grief! Am I seeing this correctly that on Partstree.com a ring set costs $38? Does that sound right?

If so, this $15 mower is going to get expensive quick....
 

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.... But I am wondering how tough it will be to replace the rings? Do you just pull them out and put the new ones in? Or is there some type of calibration?

I mean these are basically just washers like in a faucet, right? Except they keep the oil from leaking rather than water...
Same principle except obviously faucet washers don't have to turn at 3K rpm and operate in temperatures of several hundred °F. :D

Here's another good read about what they have to do and some things to look out for when replacing them.

Piston, Cylinder, and Ring Operation - Aircooled.Net, Inc.
 

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Discussion Starter · #18 ·
Thank you so much for all your links. After reading the full manual on the Tecumseh engine and the latest one on the function of the rings I think I may be able to take on this project....

That Tecumseh manual on how to disassemble and reassemble the motor was great.
 

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Mattinky,

If it is black smoke coming out then you are looking at a fuel issue with running rich. This would be my first guess. If you have debris in the carb and as you are running it it is being sucked up and blocking a jet it may bog down until it drops the debris then boost back up.

If it is white smoke then we are talking burning oil. In this case it gets a little more complicated. Valves would probably be my first guess. If you have one that is sticking then it could cause excess oil burning. If the rings are worn to a point where they are allowing oil to pass under compression then this could be your cause. something like Cylinder Leak-Down Tester
this would be my recommendation. It is a cylinder leakdown tester and would help you find out if your problem is rings or valves. you may be able to call up a shop and have them do this for you as well for a minimal fee.

Hope this helps. Feel free to contact me through Arco Lawn Equipment | Home if you have any more questions. keep me posted on what you find I will do my best to guide you through it.
 
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