Small engine breakdowns

[Redoverfarm]

Undoubtly this has been addressed before but for the life of me I can't find anything using the searchs.  There are several friends and myself that have been experiencing a failure in small gasoline engines.  Mainly compressors and generators.  Without singleing out one particular manufacturer it seems to be mostly with Briggs and Stratton.  From the information gained thusfar it is directed toward the Ethenol gasoline. 

I became the recent victim of this with a 11 month Troy Built ( Briggs engine) generator.  It has been running great for the last 2-3 months.  On Friday I changed the oil ( Every 40-50 hours) and it ran for 2-3 hours and suddenly stopped.  I checked the gas, oil and plug and they were not the problem.  So I loaded it up and took it to a lawn mower repair shop.  His diagonsis (without tearing it down) that it sounded like the valves. 

With other people I have talked to they started using "high test" gas instead of the regular gas (ethenol enhanced).  Several other people say they use a small amount of transmission fluid as a gas additive and others use "Marvel Mystery Oil". 

If it is the Ethenol gas can anybody explain what actually is happening. 

To make a long story short I ended up buying a generator to maintain working and will get the other one repaired ( still warranty in effect).

Does anyone know of another forum that might hold the answers if they are not apparent to anyone here.

[MountainDon]

I can't say with certainty, but I do believe the problem can be traced back to ethanol-gasoline mixtures causing the fuel mix entering the engine to be leaner. Our modern cars have the computer to assist in mixture changes as ethanol is added. The small engines do not.

Small engines are set to run as lean as possible to meet emissions regulations. Mix that with ethanol and I think you can get problems. The engines run hotter on Ethanol blends. So I believe that adjusting the carbs (if you can) to run richer on the fuel you use may be an answer to the engine burnout problem. Also being certain to have free flow of cooling air is important.

Some small engines may have problems with rubber parts not being compatible to higher ethanol fuels. I have heard that the ethanol can be a bigger problem with 2 stroke engines, but have nothing to back that up.

[MountainDon]

Did a Google. There seem to be many claims that ethanol and small engines do not mix well. Problems seem to come from leaning out, extra heat being produced and fuel system parts fsilures, with the finger being pointed at ethanol.

If possible buy non ethanol laced fuel. That's pretty much impossible these days.

Other say using premium fuel will result in lower engine temperatures. I'd like to see empirical proof in place of anecdotal evidence.

Some say use stabilizer in all the fuel put through small engines. Ditto my comment above.

I have not had any problems, but run all my small engines at 8800 feet. That altitude enriches the mixture. I had to lean the generator and the chain saw slightly to get them to run well at altitude.

[glenn kangiser]

Mikey B who owns a saw shop told me to run Chevron premium w/techron for the small engines.  He also uses Stabil in his mixed gas.

[Redoverfarm]

Don I have heard that chain saws are not experiencing this problem as it is mixed oil and may gain some lubrication from that mix.  Have you ever heard of the transmission oil added to the gas?

[peternap]

Don I have heard that chain saws are not experiencing this problem as it is mixed oil and may gain some lubrication from that mix.  Have you ever heard of the transmission oil added to the gas?

Actually, they do John. Part of the problem is the gas but the bigger problem, especially with saws, is that the manufacturers lean them out to pass the EPA emissions regs. You don't see the problem as much in saws for two main reasons.

1. Saws aren't run non stop as long as things like compressors...
2. Most saw owners that use them a lot, re tune them often. I tune the carbarators on mine 2 or three times a year to account for the weather.

[Squirl]

Running a very small amount of 2 cycle oil through a 4 cycle engine shouldn't do any damage.  Just be careful not to foul a plug.  It makes logical sense.  Give it a shot.

[MountainDon]

I also meant to say that I use only synthetic oils. In a 4 stroke they help the engine run cooler as well as lubricating better especially when cold starting. In a 2 stroke all I can say is that the innards are cleaner in a 2 stroke that used synthetic.

[Windpower]

Marvel Mystery Oil is great stuff

I trust it enough to put it in my Cessna (4 oz per 10 gals of gas) -- it eliminates lead fowling problems with the 100 LL that I burn

I routinely add MMO to all my small engines -- I have a 25 year old briggs (the infamous vertical shaft 8 HP motor)  in an old mower that still runs perfectly -- it must have over 1000 hours on it and I burn ethanol gas all the time (most of the gas in the Chicago subs have it)

maybe it is the MMO

the other effect that is quite noticiable with the MMO is better power at low RPMs -- the mower will definitely 'lug' better

[cordwood]

After 30 + years of wrenching on small engines has taught me a couple of things, One would be that saws have less problems with valves because they DON'T HAVE VALVES
One problem with alcohol type bended fuels is they attract moisture, As moisture fills the bottom of the bowl it restricts the fuel going through the main jet and starts leaning out the mixture. Additives that help displace moisture work as well as other additives for the lean condition. Another problem is that newer fuels are dryer and don't contain any kind of lubricant (like leaded fuel did) so wear on valves may be faster.
The 2 most common problems I found when I worked in a small engine shop was water in the gas and too light or too heavy of oil in the crankcase. Too thin and it gets really thin when the little engine gets hot, Too heavy and it won't "sling" and reach all the places it needs to. Even the pressure lube engines require a certain amount of oil sling to lubricate some parts in the crankcase.
I still do work for several commercial lawn care people and with just 30w dead dino oil have had no oil related failures.
BS engines are in my opinion the worst of all the small engines, The old ones were pretty good but now they are,....well,...OLD! Many of the newer twin cylinder BS 18hp & up have a problem with losing power to one coil and running on one cylinder for too long one of the rods will break and go through the block. I have several "vented" blocks that the root cause was traced to a diode in the kill wire to the coil.

[glenn kangiser]

Interesting, Cordwood.  I have a small 2kw? ice chest size - BS generator but it actually has a nice little Mitsubishi engine for a power plant.

[cordwood]

Mitsubishi makes pretty good little engines. I have seen many small tractors with 2 & 3 cylinder Mitsies in them that ran forever. That also kind of takes it out of the Briggs & Stratton small engine thing though
Even Briggs knows their stuff is ailing, In the past ten years or so they have tried to copy almost every other brand made.

[Redoverfarm]

I ran across these the other day and thought some members might find the sites useful especially if you have a machine that doesn't want to cooperate.




Bushhog Garden Tractors (a Yahoo group) http://groups.yahoo.com/group/bushhog_gardentractors/

Chainsaw Collectors.se (same software as our forum) http://www.chainsawcollectors.se/

Do It Yourself Forum (covers a lot of different types of repairs) http://forum.doityourself.com/

The Forestry Forum (chainsaws and more) http://www.forestryforum.com/board/index.php?board=9.0

Gravely Forum (Yahoo Gravely information Forum) http://www.gravelyinfo.com/

Handyman Forum (lots of areas of repair covered here) http://www.handymanwire.com/ubbthreads/ubbthreads.php

Hobby Talk Forum (Hobby Talk small engine forum) http://www.hobbytalk.com/bbs1/forumdisplay.php?f=107

Lawn Mower Central (mainly mowers, but other stuff too) http://s15.invisionfree.com/Lawn_Mower_Central/

Michael's Tractors (Simplicity and Allis Chalmers Garden Tractors) http://www.michaelstractors.com/forum/default.asp

MyTractorForum.com (an extensive forum covering a lot of ground) http://www.mytractorforum.com/

Sharing Small Engine And Garden Tractor Secrets (a small engine & tractor forum)

Smokestak (antique Engine forum) http://www.smokstak.com/index.php

The Best Forum Snowblower & Lawnmower Forum (same software our forum) http://www.opeonthenet.com/phpBB2/index.php