# Craftsman blower



## dennisl (Nov 21, 2006)

I have the infamous 25cc Craftsman blower model 358.797120. It will not start no matter what I do. Getting spark and fuel, but I think the compression is low. Checked it with a very old auto compression tester and it reads 65 psi. I read somewhere to squirt oil into it and check it again, which I did and it went over 100 psi temporarily. Questions - what is the next step? I can't really see any scoring on the cylinder from the exhaust opening. Is it normally just the piston ring? Unit is only 18 months old. How much trouble and expense to replace the piston and/or ring. Any info appreciated.


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## hankster (Jan 1, 1998)

Most likely the ring is stuck. With the muffler off move the piston so the ring is visible. Now use a small screwdriver and see if the ring is free in the groove by pressing on it.... it should move slightly. If the ring is stuck you may be able to fix it without replacing the piston and ring.


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## dennisl (Nov 21, 2006)

hankster said:


> Most likely the ring is stuck. With the muffler off move the piston so the ring is visible. Now use a small screwdriver and see if the ring is free in the groove by pressing on it.... it should move slightly. If the ring is stuck you may be able to fix it without replacing the piston and ring.


You were right - I took the engine apart and the ring was basically "frozen" in place. I tried carefully to get it loose, but it came apart in pieces. Next question, can I just replace the ring, or do I have to replace the piston, rod, etc. I've never done this before (obviously) so do you think I should even attempt it. Thanks.


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## 30yearTech (Sep 14, 2006)

You can replace just the ring, but you have to make sure the ring land is good and clean so the new ring will not stick as well. Parts for this unit are not that expensive so you might just want to consider replacing the piston when you factor in the time required to clean it.


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## hankster (Jan 1, 1998)

It is best to heat the piston/ring before trying to remove it. If you are careful you can remove the ring when it is heated without breaking it (I know... too late now to tell you that!). A new ring is a couple of bucks, a new piston is about 20 (includes the ring).

If you heat the pistion slightly (heat helps to soften the carbon), you can use the broken ring as a scraper to clean out the groove (maybe takes 10 min. to do). Once nice and clean you can then put in the new ring and all should be fine.


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## dennisl (Nov 21, 2006)

Hankster - thanks for all your help. I had bought another blower, but decided to try and fix the old one just for the heck of it. I just bought the ring and gasket kit, and the parts came today. I put it all back together, and it cranked the second time I pulled the rope. AMAZING. It's running as good as ever. It may crap out again tomorrow, but at least I got it fixed. Thanks again - you folks are awesome!


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## hankster (Jan 1, 1998)

It'll run until the ring seizes again but now you know how to fix it


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## jetrail (Dec 7, 2005)

well this was definately interesting , funny part is if its the same blower as im thinking (the one that has both levers on the left side ) then i had about 4 of them come through and never knew how to fix them , one was a craftsman , 2 snappers , and a maculloch , all the same design too , all low compression , also what causes the rings to stick on these ?


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## ZukiJon (Nov 15, 2006)

Fuel mix, heat, carbon build up ?


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## Old_Man (Apr 4, 2007)

*Don't run blower too long*

My wife likes the light weight blower and we have gone through a number of them of them over the years.Typical life is two seasons. If you have a heavy job and run the blower too long at high speed, you may note that the unit starts to slow down, and then fails to start again after that. Side of piston and ring have groves cut that can be seen from exhaust port after removing muffler. Very low compression-- won't move your finger off the spark plug hole when cranking. I have always assumed that both cylinder head and the piston would have to be changed, which does not seem to be cost effective.

Is this a bad assumption?


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## Rpeters123 (Oct 19, 2005)

*Cheapo fix?*

If carbon causes the ring to stick - yes- why not soak the ring block/muf hole and spark plug and pull rope few times -spray again let soak over night. I also heard the flywheel keys sligtly shears on this model true ? Try it see if works I am a cheap fixer but not a hack. I like trying new methods. This site is great!!


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## oscaryu1 (Mar 25, 2007)

yup im gonna soak mine today =) this site IS great !v


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## geogrubb (Jul 28, 2006)

If you will empty the tank and use enough fuel(regular mix 40:1, 50:1 etc.) to run at idle for 30 minutes, mix this fuel with Chevron Techron fuel system cleaner at a rate of 1/4 Chevron Techron and 3/4 fuel. Start the motor and let it idle(do not rev the motor it will caues the carbon to come off in chunks) until all the fuel is gone, the carbon and junk will start to drip out of the muffler, when it runs out of fuel remove the muffler and clean it and the spark arrestor with carb cleaner or a torch. The piston, rings and combustion chamber should be spotless, you have also done a little carb cleaning. Chevron Techron does not recommend this product for 2-cycles, I think that is because people have a tendency to want to rev the motor to blow out the bad stuff which causes the carbon to come off in chunks and break something. I have used it on Stihl, Lawnboy, Tec and Polan blower, trimmer and mowers with good success. Have a good one. Geo


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## oscaryu1 (Mar 25, 2007)

where can u get cheveron techron fuel system cleaner? walmart heb?


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## geogrubb (Jul 28, 2006)

You can get Chevron at walmart, autozone, advance, most anywhere that sells automotive, it's about $7-8 for 12oz bottle. Have a good one. Geo


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## oscaryu1 (Mar 25, 2007)

thanks geo =)


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## ribertgropius (May 22, 2007)

*You guys are amazing*

I just posted a question regarding the same 25cc engine, and then I looked at these postings and saw this thread. It sounds like my engine has this same problem; no markings on the cylinder, but the ring isn't doing its job.

I had a question regarding loosening the existing ring; am I correct in understanding that the ring has to be removed to clean out the groove? How the heck do you get the existing ring off? I noticed when I looked at mine that there is almost no clearance where it joins; do you use a needle, or pick of some sort to try to open it? 

Thanks to all for sharing their wisdom.

Robert


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## ribertgropius (May 22, 2007)

*Success!*

Thanks to all for their advice. I received the new ring this week and put everything back together last night. Blower starts right up and runs just fine for now.

The old ring was indeed stuck with carbon; in trying to loosen it I broke it, but then used the broken ring to clean out the groove. I was able to put the new ring on just using my fingers to slip it over the piston and sliding it down into position. I used a small screwdriver to gently press the side of the ring as I pushed the piston into the cylinder and it went in without any problems.

The total investment to fix it was about $8; $3 for the ring and $5 for shipping/handling from my local mower store. Of course, that does not count the time spent learning about the blower, but that was the fun part! This forum is a wonderful resource.

Hopefully my ring will not get stuck again for a while! What was interesting to me was how clean the cylinder looked when I took it apart; the compression loss was because of the ring not being able to expand properly. With the new ring, I could feel the compression difference immediately.

Robert


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