This model is a plastic breather valve with a 3/8″ (≈15.5 mm) external thread and a total height of 90 mm, with no adapter needed: it fits directly onto crankcase necks with a 3/8″ internal thread, a size common on many piston air compressor models.
Technical Specifications
| Parameter | Value |
|---|---|
| Purpose | Breather valve (crankcase vent) for an air compressor |
| Thread | 3/8″ (≈15.5 mm), external |
| Height | 90 mm |
| Body material | Plastic (polyamide/ABS — heat-resistant) |
| Design | Threaded fitting + protective cap with ventilation slots |
| Kit contents | Breather valve (no adapter needed — 3/8″ thread fits standard necks) |
| Compatibility | Piston air compressors with a 3/8″-threaded crankcase neck |
| Operating temperature, °C | to be confirmed against the compressor’s datasheet |
| Weight, g | to be confirmed |
Design Features
The breather’s body is a single-piece plastic molding with a 3/8″ threaded fitting and a protective cap featuring ventilation slots — these increase the breathing surface for airflow while limiting the entry of dust, debris, and oil spatter into the crankcase. The unit’s overall height is 90 mm, worth checking against your compressor if clearance above the neck (under a hood or housing) is limited.
Installation Guidelines
- Stop the compressor and let the crankcase cool down.
- Unscrew the old breather or plug, and clean the neck’s threads of old sealant and oil residue.
- Confirm the neck’s thread is an internal 3/8″ (compatible with the breather’s external thread).
- Use PTFE tape on the threaded joint for a proper seal if needed.
- Hand-tighten the breather until snug, then give it a light additional turn with a wrench — don’t overtighten, to avoid stripping the neck’s threads or cracking the cap.
- Start the compressor and, after 10–15 minutes of operation, check the fitting for oil leaks.
Common Installation Mistakes
- Installing a blind plug instead of a breather — pressure builds up in the crankcase and oil is pushed out through the seals.
- Thread mismatch — trying to screw a 3/8″ breather into a neck with a different thread pitch/diameter without checking compatibility first.
- A clogged filter/vent slots — produces the same effect as a blind plug: pressure rises and oil is forced out.
- Overtightening during installation — risk of damaging the neck’s threads or cracking the plastic body.
FAQ
Can this breather be installed without an adapter? Yes, as long as your compressor’s crankcase neck has an internal 3/8″ (≈15.5 mm) thread. No adapter is needed in that case.
What if my neck’s thread isn’t 3/8″? You’ll need an adapter for the correct size — check your compressor’s neck diameter before ordering.
How do I know it’s time to replace the breather? If oil is leaking from the neck, you hear a hissing/whistling sound, or the breather is visibly clogged with dirt, it’s time to replace it.
Does the 90 mm height matter for installation? Yes, if the breather is being installed in a tight space (under a housing, near a belt or pulley) — check the clearance before purchasing.
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