vapor lock

English

Alternative forms

• vapour lock

Noun

vapor lock (countable and uncountable, plural vapor locks)

1. (mechanical engineering) A problem mostly affecting gasoline-fueled internal combustion engines, where the liquid fuel changes state from liquid to gas while still in the fuel delivery system, reducing the pump pressure and causing transient power loss or complete stalling.
2. (especially mechanical engineering) Synonym of air lock.
   • 2017 December 12, National Transportation Safety Board, “2.4.1 Loss of Propulsion”, in Marine Accident Report: Sinking of US Cargo Vessel SS El Faro, Atlantic Ocean, Northeast of Acklins and Crooked Island, Bahamas, October 1, 2015‎^[1], archived from the original on 15 May 2022, page 185:

     The Coast Guard Marine Safety Center modeled and analyzed the lube oil levels in the main engine sump in a static condition. The safety center concluded that with 1,226 gallons of oil in the sump, as was likely on the accident voyage, and a 5-foot trim by the stern (0.4°), the bellmouth opening of the line leading from the sump to the lube oil pumps would break the oil's surface at an 18° port list. At that point, the bellmouth would no longer be submerged in the lube oil and air would enter the pumps, causing a vapor lock.

Related terms

• air lock
• hydrolock
• hydrostatic lock