Owner’s manual
What size trimmer line for Craftsman?
For the Craftsman gas line trimmer model 316791961, most cutting heads are designed to run 0.065 inch or 0.080 inch trimmer line; we recommend confirming the exact diameter and winding direction in the 316791961 owner's manual before you buy or respool.
Quick way to choose the right line
- Check the cutting head label or spool for a stamped line diameter (often 0.065 or 0.080).
- Match the line shape to your work: round for general trimming, twisted for lower noise, serrated for heavier weeds.
- Use the thickest line the head is rated for; thicker line can reduce breakage.
- Avoid oversizing; line that is too thick can jam the head and overload the flexible drive shaft.
- Replace old, brittle line; it snaps more and feeds poorly.
Typical line sizes and what they’re best for
| Line diameter | Best for | What you’ll notice |
|---|---|---|
| 0.065 in | Light grass, edging | Smooth feed, less engine load |
| 0.080 in | Medium grass, light weeds | Better durability, slightly more load |
| 0.095 in | Heavy weeds (only if rated) | More cutting power, higher load and fuel use |
Why it matters
Using the correct line diameter helps your Craftsman trimmer feed properly, cut cleanly, and avoid premature wear on the cutting head, gearbox, and drive components.
If the trimmer isn’t cutting well after changing line
A line issue can look like an engine problem. These tune-up items often help:
- Install a fresh spark plug 794-00082 if starting is hard or power is weak.
- Clean or replace the air filter (restricted airflow reduces RPM).
- Drain old fuel and refill with fresh, properly mixed fuel (for 2-cycle models).
Last updated: February 2026
How to replace trimmer head on Craftsman Weedwacker?
To replace the trimmer head on your Craftsman gas line trimmer model 316791961, lock the shaft, unthread the old head (most heads loosen by turning clockwise because they use left-hand threads), then thread the new head on by hand and tighten it securely without cross-threading. Confirm the exact thread direction and locking method in the 316791961 owner's manual.
Before you start
- Shut the engine off and let the muffler and gearbox cool completely.
- Disconnect the spark plug boot so the trimmer cannot start.
- Wear gloves; the cutting head area can have sharp edges and debris.
- Clean grass and dirt from the head and shield so you can see the fasteners.
Steps to remove and install the trimmer head
- Lock the shaft: Align the locking hole/slots in the cutting head or gearbox and insert a small screwdriver or locking pin.
- Remove the head: With the shaft locked, turn the head to loosen it. Many Craftsman style heads use reverse (left-hand) threads, so loosening is often clockwise.
- Inspect the threads: If the head fought you, check for damaged threads or wrapped line.
- Install the new head: Start threading the replacement head on by hand to avoid cross-threading.
- Tighten: Lock the shaft again and snug the head firmly. Do not use excessive force that can damage the gearbox.
If the head will not come off
- Soak the threads with penetrating oil and wait 10 to 15 minutes.
- Re-seat the locking pin; if it is not fully engaged, the shaft will still spin.
- Tap the head lightly to break debris loose (avoid striking the fuel tank or shaft).
- If the head is cracked or wobbling, replace it rather than forcing it.
Common symptoms and what they usually mean
| Symptom | Most likely cause | What to do |
|---|---|---|
| Head spins but will not loosen | Shaft not locked | Re-align slots and reinsert locking pin |
| Threads bind immediately | Cross-threading | Back off, clean threads, restart by hand |
| Excess vibration after install | Head not seated or worn parts | Reinstall; inspect gearbox/shaft |
Why it matters
A properly installed cutting head protects the gearbox and flexible drive components from shock loads, reduces vibration, and helps the trimmer feed line consistently.
Last updated: February 2026
How to replace line on Craftsman gas trimmer?
To replace the cutting line on your Craftsman gas line trimmer model 316791961, shut the engine off, remove the spark plug wire for safety, then reload the trimmer head with the correct diameter line and wind it evenly so both ends are the same length. Use the 316791961 owner's manual for the exact line size and head style used on your unit.
Quick steps to reload the line (most bump heads)
- Turn the trimmer off and let the muffler and cutting head cool.
- Disconnect the spark plug boot so the engine cannot start.
- Clean grass and debris off the cutting head so the line feeds smoothly.
- Insert the line into the eyelets (or through the center, depending on head design).
- Wind the line in the direction of the arrows on the head.
- Do not press the bump knob while turning; keep steady tension.
- Stop when about 5 inches of line remains sticking out on each side.
What to check before you start
Using the wrong line size or winding direction is the most common reason a head will not feed.
| Check | What “right” looks like | If it’s wrong |
|---|---|---|
| Line diameter | Matches the manual spec | Line jams or won’t feed |
| Winding direction | Follows arrows on the head | Line backs out or tangles |
| Equal tails | Same length on both sides | Vibration, uneven cutting |
| Head cleanliness | No packed debris | Poor bump-feed action |
If the line will not feed after reloading
- Make sure the line is not welded together from heat (replace with fresh line).
- Rewind with firm, even tension and neat layers (no crossovers).
- Inspect the head for cracks or worn eyelets; replace the head if damaged.
- If the head assembly is worn, replace the complete line trimmer cutting head 753-05045.
Why it matters
Correct line size, correct winding direction, and equal line lengths prevent tangles, reduce vibration, and help the bump-feed mechanism advance line consistently while trimming.
Last updated: February 2026
Do trimmer plus attachments work with Craftsman?
Yes. TrimmerPlus attachments work with Craftsman powerheads that use a TrimmerPlus-compatible coupler (typically a split-shaft, attachment-capable connection). For Craftsman model 316791961, confirm the coupler style and locking method shown in the 316791961 owner's manual before you buy an attachment.
How to confirm your trimmer is attachment-capable
Check these items on your Craftsman 316791961:
- Look for a coupler on the shaft (a clamp-style connection point where the shaft separates)
- Confirm there is a release button or locking pin that aligns with the attachment
- Inspect the inner drive interface (commonly square or splined, depending on the system)
- Make sure the attachment packaging states it fits TrimmerPlus-compatible couplers
- Compare the connection details to the diagrams and instructions in the manual
Quick compatibility checklist
| What must match | On your Craftsman 316791961 | On the attachment |
|---|---|---|
| Coupler style | Split-shaft coupler | Same coupler standard |
| Locking method | Button or pin | Same position and engagement |
| Inner drive | Square or splined | Same shape and depth |
| Fit at coupler | Proper clamp fit | Designed for that coupler size |
If an attachment slips or will not spin
Work through these common causes:
- Attachment not fully seated in the coupler before tightening
- Locking button or pin not engaged in the hole
- Debris or damage inside the coupler preventing full engagement
- Worn inner drive components (especially after heavy edging or brush work)
Why it matters
When the coupler and inner drive do not match, the attachment can wobble, slip under load, or fail to drive the head properly. Correct fit protects the drive system and improves cutting performance.
If the engine bogs under load after installing an attachment, basic tune-up parts often help; start with the correct spark plug 753-05784 and a clean air filter.
Last updated: February 2026
