The MS440 vent valve is the tank breather valve for MS440 044 chainsaws. A black plastic body, a gold sintered bronze disc on top, a ribbed collar in the middle and a snap base at the bottom, fitted in the tank vent seat. The sintered disc is a web of open pores: air passes freely while oil mist and water are held at the pore mouths, so the tank breathes under heat, does not swell and does not leak at the vent. If the tank cannot breathe and the fuel cap pulls stiff, or oil mist escapes at the vent, check the sintered disc first; a broken snap base means the whole valve goes. The disc is not washable and cannot be replaced on its own, so a fresh valve restores the tank breathing. This valve is made for MS440 and 044 tanks; the MS360 036 and MS340 034 are similar models from the same class, so compare the old valve size and the vent seat, or send a photo to confirm.

 FAQ 

Q1: What does the gold disc on the valve do?

It is a sintered bronze breather. Air passes through its open pores while oil mist and water are held back, so the tank can vent without leaking.

Q2: Is the MS440 vent valve the same as the 044?

Yes. MS440 and 044 are the old and new names of the same saw, and this valve fits that tank.

Q3: Does it fit other models?

The MS360 036 and MS340 034 are similar and are commonly listed as common fits, but not guaranteed, so compare the old valve or send a photo before ordering.