Stihl 028 Wood Boss AV Muffler (Install Guide)
To fit a muffler on a Stihl 028 Wood Boss AV, first confirm the saw’s version and the replacement assembly’s fit. Work outdoors with a cool, stopped saw and the spark-plug boot removed. Inspect the port and threads, install the specified seal and shield, then tighten to the correct service specification. Never run the saw with a loose or leaking muffler.
A common complaint is that a replacement muffler looks right but will not sit flat, or that the saw gets louder again after a short run. On an older 028, those clues matter: a wrong assembly, damaged threads, or a failed seal can turn a routine repair into a safety risk.
I approach this job as a fit-and-condition check, not just a bolt swap. The 028 name alone does not identify every revision or replacement part. Confirm what is on your saw before ordering, and use the service information for its exact version. If the cylinder, exhaust port, or mounting threads are damaged, stop and address that problem first.
Equipment Setup and Muffler Safety Preparation
This stage makes sure the saw is safe to handle and that the replacement parts match the actual machine. The 028 is approximately 47 cm³, but that figure does not identify the muffler revision. Check the model plate and applicable documentation, then compare the old assembly and mounting layout before beginning work.
Confirm the muffler and parts
A muffler assembly may include more than the main can: a deflector, heat shield, screen, or gasket may also be needed. A heat shield helps keep hot exhaust away from nearby parts. A gasket or seal closes the joint between the muffler and cylinder; use the type specified for the saw and replacement assembly.
- Record the saw’s model details and serial number. If the plate is hard to read, ask a Stihl dealer to help identify the version.
- Compare the replacement muffler’s mounting points, outlet direction, shield, and deflector with the original and the correct parts information.
- Obtain the specified gasket or seal and any required cover or shield. Do not assume an old gasket can be reused.
- Do not choose a muffler by appearance alone or rely on a generic part listing that does not confirm fit.
I have seen this mismatch pattern in repair discussions: the muffler body appears close, but the outlet or shield does not line up with the saw’s covers. Treat that as a fit failure, not a reason to bend parts or force a bolt.
Prepare the saw and work area
A cool saw reduces burn risk, while removing the spark-plug boot helps prevent an accidental start during service. Work outdoors, away from flames and ignition sources. Wear eye protection and cut-resistant gloves, and keep the chain brake engaged while handling the saw.
Clean loose dirt and sawdust from around the muffler and cylinder before opening the joint. Debris near the exhaust port can fall into the engine when the muffler comes away. Arrange the parts in order as you remove them, so shields and deflectors go back in their proper positions.
Muffler Removal, Inspection, and Installation
Removal exposes the exhaust port and mounting surfaces, so keep the area clean and avoid levering against the cylinder. The new muffler must sit flat, use the specified sealing part, and clear nearby components. Fastener torque depends on the exact saw version and hardware; there is no universal 028 value to guess.
Remove and inspect the old muffler
Remove the muffler cover or deflector if the saw’s configuration requires it. Loosen the muffler fasteners evenly, then lift the assembly away. Do not pry against the cylinder or force a stuck fastener; damaged mounting threads can make the repair more involved.
With the muffler removed, inspect the exhaust-port area and the visible piston surface. Look for scoring or signs of heat damage. Check the muffler outlet and any fitted screen for blockage, cracks, or other damage. Do not push carbon or debris into the cylinder. If the piston or cylinder looks damaged, or a fastener thread is stripped, stop and have the condition assessed before installing parts.
Fit the replacement muffler
Place the specified new gasket or seal as directed, then orient the muffler, deflector, and heat shield correctly. Start each fastener by hand. This helps reveal cross-threading early; a bolt that will not turn smoothly should not be forced.
Before tightening, confirm that the muffler sits flat and does not touch the chain, chain brake, fuel lines, or plastic covers. Tighten fasteners evenly, using the service specification for the exact version and hardware. Do not guess a torque, overtighten, or add threadlocker or sealant unless the applicable Stihl instruction calls for it.
| Check | Correct result | Stop if… |
|---|---|---|
| Muffler fit | Assembly sits flat at the mounting face | It rocks, leaves a gap, or needs force |
| Fasteners | Start smoothly by hand and tighten evenly | Threads bind, spin, or appear damaged |
| Seal | Correct specified gasket or seal is in place | The seal is missing, torn, or unverified |
| Shield and deflector | Installed in the intended orientation | Parts are cracked, loose, or misaligned |
| Clearance | No contact with chain, brake, lines, or covers | Any part touches or blocks another |
A muffler that will not seat flat is a reason to stop and recheck the part, seal, and mounting surface. Do not pull it into place with the fasteners. A poor fit can create an exhaust leak or stress the mounting points.
Field Cutting and Landscaping Operation
A short, controlled check after assembly can reveal leaks, loose parts, or contact before the saw returns to work. It is not a substitute for correct installation. Keep the test outdoors, follow the operator manual, and stop the engine at once if you hear unusual noise or detect exhaust escaping at the joint.
Start-up and leak check
Reinstall covers and reconnect the spark-plug boot. Start the saw outdoors with the chain brake engaged and the bar clear of people and objects. Follow the starting and operating instructions in the applicable operator manual.
Listen for abnormal noise and watch for unusual vibration or movement at the muffler. Check for visible signs of exhaust leakage near the mounting joint without touching hot parts. Stop immediately if the muffler is loose, leaking, or contacting another component. Do not run the saw with a missing muffler, blocked outlet, or failed seal.
Let the saw cool before any recheck. Confirm mounting security as directed by the service instructions. If the muffler loosens again, do not simply tighten harder; inspect the threads, seating surfaces, and compatibility of the assembly.
Common repair scenarios
These examples describe how to respond to common fit and inspection findings; they are not proof of a specific fault on every 028. The key is to distinguish a correctable parts mismatch from damage that needs repair. If the cause is unclear, pause rather than operate the saw to “see if it settles.”
| Finding during the job | Likely next step |
|---|---|
| New muffler holes or outlet do not align | Recheck model/version and part compatibility |
| Muffler will not sit flat | Check seal placement and mating surfaces; do not draw it in with bolts |
| Fastener will not start by hand | Stop and inspect the thread and correct hardware |
| Visible piston scoring or heat damage | Do not return the saw to service until assessed |
| Exhaust leak or renewed looseness after starting | Stop, cool the saw, and inspect fit, seal, and mounting threads |
Muffler Maintenance, Chain Sharpening, and Engine Tuning
Muffler maintenance means checking its mounting, outlet, shield, and any fitted screen for damage or blockage. Chain sharpening and engine tuning are separate service tasks. They can affect cutting performance, but they do not correct a leaking muffler or justify changing its fit or hardware.
After use, let the saw cool and check for visible cracks, loose parts, or a blocked outlet. If the configuration includes a spark-arresting screen, follow the service information for inspection and cleaning. Do not operate with an obstructed outlet or damaged muffler. Avoid pushing deposits into the cylinder while cleaning.
Keep chain and bar details separate from muffler specifications. 028 setups vary; commonly, the chain pitch is 3/8 inch and the bar gauge may be .050 or .063 inch. Match pitch, gauge, and drive-link count to the bar and sprocket. These measurements do not identify a muffler.
Use the fuel mix ratio stated in the applicable Stihl operator manual and on the oil label. Do not infer a ratio from “028” or mix oils without checking their instructions. For engine speed or carburetor work, use the model-specific service specification and a tachometer. Do not set idle or maximum speed by ear; incorrect high-speed tuning can damage the engine.
Storage and Seasonal Care
Storage checks help catch corrosion, loose hardware, or damage before the next start. They do not replace a proper repair. Put the saw away with its muffler intact and secure, and follow the operator manual for fuel and storage steps that apply to your particular machine.
Before storage, let the saw cool and inspect the muffler, fasteners, shield, and outlet. Keep the outlet clear of packed debris, and do not store the saw where its hot exhaust could contact flammable material. If you find a crack, failed seal, or loose mounting, repair it before the next use.
If the saw has been stored for a long time, inspect the muffler and surrounding parts before starting it. Check that covers are secure and the exhaust path is not obstructed. After any muffler service, keep a record of the part details and the service specification used; this makes later maintenance easier and helps identify a mismatch.
FAQ: Stihl 028 Muffler Installation
These answers cover the checks most likely to determine whether the repair is safe and compatible. The model name alone is not enough to select every part or setting. When a detail depends on the saw’s revision, use its model-specific Stihl documentation or ask a dealer to verify it.
How do I know which muffler fits my 028 Wood Boss AV?
Confirm the saw’s model details and serial number, then match the replacement assembly to the correct parts information. Compare mounting points, outlet direction, and required shield or deflector. Do not rely on appearance or the “028” name alone.
Is there one muffler torque value for all 028 saws?
No universal value is safe to assume across all versions and replacement hardware. Use the service specification for the exact saw. If you cannot confirm it, ask a Stihl dealer or qualified service provider rather than guessing.
Can I reuse the old muffler gasket?
Use the gasket or seal specified for the assembly and follow the applicable service instructions. Do not assume a used seal is suitable. A missing or damaged seal can allow hot exhaust to leak at the joint.
Can I use sealant if the muffler leaks?
Do not use an improvised sealant. Confirm the part and seal are correct, inspect the mating surfaces and threads, and follow Stihl’s instructions. A damaged mounting surface or thread needs proper repair, not a sealant workaround.
What should I do if a muffler bolt will not start?
Stop and inspect the fastener and threaded hole. Do not force it or use it to pull the muffler into place. Cross-threaded or damaged threads can prevent secure mounting and may need repair.
Is it safe to run the saw briefly without the muffler?
No. Do not operate the saw with the muffler removed, a leaking joint, or a blocked outlet. A loose or incorrectly seated muffler can direct hot exhaust onto nearby parts or the operator.
Does the 028’s chain pitch tell me which muffler to buy?
No. Chain pitch, bar gauge, and drive-link count are cutting-system details, not muffler specifications. Match those chain details to the bar and sprocket, and identify the muffler using the saw’s version and parts information.
What if the piston looks scored through the exhaust port?
Do not return the saw to service based only on a muffler replacement. Have the engine condition assessed by a qualified technician. Visible scoring or heat damage can point to a problem beyond the muffler.
Do I need to retune the engine after installing a muffler?
Do not change engine settings by ear. If tuning is needed, use the model-specific service data and a tachometer, or have a qualified technician perform the work. Incorrect high-speed settings can damage the engine.
When should I stop the repair and seek service?
Stop if the cylinder, exhaust port, or mounting threads are damaged; the muffler will not seat flat; a fastener will not engage correctly; or a leak remains after installation. Do not force hardware or operate the saw to test a suspect repair.
(This article was written by one of our staff writers, Elliott Fowler. Visit our Meet the Team page.)
