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SBW#3 – Craftsman Leaf Blower Piston Replacement

Do you have one of those 2 cycle leaf, weed trimmers or any other small 21/25cc 2 cycle engine power equipment?  If you do and you have ran into the problem I did the chances are the solution is pretty easy to fix if you are a DIY person. Otherwise, you can take it to a small engine repair place and shell out some money but is it really worth that?

After a hard fall use blowing leaves and a winter break the leaf blower failed to start in the spring. I checked all the usual suspects – gas, fuel to the cylinder, spark plug, spark, etc and everything looked fine. However, I noticed as I was pulling the starter cord that the compression seemed a little weak. In fact it was not just a little weak but barely noticeably having a compression. So I had an idea. I grabbed my cylinder compression tester and the compression was well below what the specification called for in order to fire. So much below specification that it was 50% of what it was supposed to be.

So I tore apart the unit and pulled out the piston in which the ring was completely gummed in a compressed state, unable to expand. Since I didn’t have any parts wash solvent it was going to be cheaper for me to run down to the local Sear’s Parts Center and grab a new one. I’ve included a link to both the Sear’s Parts Direct piston and rod part and the Amazon equivalent. Both work on the following brands: Craftsman, McCulloch, Weed Eater, Poulan and Husqvarna.

I put the new one on, oiling the piston and cylinder to reduce initial friction until the break completed to minimize damage. After reassembling the unit, it started up. Initially for a week or 2 when I went from idle to full throttle the engine would bog down like it was not getting the compression or right fuel / air mixture but after about 2 weeks I could go from idle to full throttle without any hesitation.

To this day – nearly a year later – the engine still runs great and the leaf blower still runs like a charm.

Here is the video. I apologize the fact that I did not record the tear down process but it is essentially the opposite of the assembly process.

Sear’s Parts Direct Part

Amazon Link
Piston and Rod Kit


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3 thoughts on “SBW#3 – Craftsman Leaf Blower Piston Replacement”

  1. If old gasoline sits in a leaf blower’s fuel tank for an extended period of time, it can accumulate water and, as a result, cause problems when you try to start the machine.

    1. I cannot find your model number at https://www.searspartsdirect.com – assuming it is a Craftsman model. Mine particular model is a Craftsman 358794765. For that particular model the piston part number is 545081864. Hopefully this link will work for you and maybe this part is what you are looking for also. Not sure as it appears it’s used in multiple leaf blower models. https://www.searspartsdirect.com/product/5phyziar4m-0071-358/id-545081864

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