Homemade exhaust for your old lawnmower

Step 3 Fabricate and assemble the muffler body

To make the muffler body, I used a 12 inch length of 1 inch diameter pipe, into which I drilled 5 3/16 inch holes. I discovered that two holes was not enough and 5 seemed to be OK. You can experiment with the number of holes if you like, and a 12 inch pipe is probably overkill.

Before and during drilling, I wet the steel with WD-40 (cutting oil may work better) to cool the drill bit so as not to wear it out. The metal is quite thick and I broke 2 drill bits by trying to rush things. Take your time and use plenty of oil.

After the holes are drilled, clean up the pipe to remove any metal particles and cut a short length of fiberglass tape. Roll it up and stuff it into the end of the tube. The fiberglass will serve to deaden the noise a little,but it may also come flying out of the exhaust holes when the engine is running. It helps to cut the fabric as little as possible so as not to create many loose threads.

Screw the pipe cap on tightly. You can remove the cap or disassemble the muffler entirely to repack or repair it in the future.

Comments

[mpandersen]

Good article, I would recommend Automatic Transmission Fluid (ATF) as a cutting lubricant, you should have some lying around ...