Wet sump

A wet sump is a lubricating oil management design for four-stroke piston internal combustion engines which uses a built-in reservoir for oil, as opposed to an external or secondary reservoir used in a dry sump design.

Four-stroke engines are lubricated by oil which is pumped into various bearings and thereafter allowed to drain to the base of the engine. In most production cars and motorcycles, which use a wet sump system, the oil is collected in a three to seven quart (3 to 7 L) capacity pan at the base of the engine, known as the oil pan or sump where it is pumped back up to the bearings by the oil pump, internal to the engine.

A wet sump offers the advantage of a simple design, using a single pump and no external reservoir. Since the sump is internal, there is no need for hoses or tubes connecting the engine to an external sump which may leak. An internal oil pump is generally more difficult to replace, but that is dependent on the engine design.

However, the wet sump design is entirely unsuitable for a racing application, for example, as the large g force pulled by drivers going around corners causes the oil in the pan to slosh, starving the system of oil for a small period of time. This can damage the engine. Early stationary engines employed a small scoop on the extremity of the crankshaft or connecting rod to assist with the lubrication of the cylinder walls by means of a splashing action. Modern small engines, such as those used in lawnmowers, use a "slinger" (basically a paddle wheel) to perform the same function.

See also

The Porsche 996 3.4 and 3.6 are not wet sump engines. Porsche has internally created an integrated oil compartment but not external to the engine. The 3.4 and 3.6 engines use multiple return oil pumps along with a pressurization pump.


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Look at other dictionaries:

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  • wet sump lubrication — The usual engine lubrication system in which the oil is carried in a pan below the crankshaft. Such a system relies on gravity draining the circulated oil and needs no return pump …   Dictionary of automotive terms

  • sump lubrication — See dry sump lubrication wet sump lubrication …   Dictionary of automotive terms

  • sump — [sʌmp] n [Date: 1600 1700; Origin: sump swamp (15 20 centuries), from Middle Dutch somp or Middle Low German sump wet ground ] 1.) the lowest part of a ↑drainage system, where liquids or wastes remain 2.) BrE the part of an engine that contains… …   Dictionary of contemporary English

  • sump pump — a pump for removing liquid or wastes from a sump. [1895 1900] * * * ▪ technology       device that removes accumulations of water or other liquids from a sump pit, the lowest point in a drainage system. If the sump pit is wet only intermittently… …   Universalium

  • Dry sump — A dry sump is a lubricating motor oil management method for four stroke and large two stroke piston internal combustion engines that uses external pumps and a secondary external reservoir for oil, as compared to a conventional wet sump system.… …   Wikipedia

  • dry sump (lubrication) system — An engine lubrication system in which the lubricating oil is carried in an external tank and not internally in a sump. The sump is kept relatively free from oil by scavenging pumps, which return the oil to the tank after cooling. The opposite of… …   Aviation dictionary

  • oil sump — A container to hold engine lubrication oil. In a wet sump oil system, all the oil is held in the crankcase. However, in the dry sump lubrication system, the oil is stored in a tank external to the engine. The dry sump system is used to make the… …   Aviation dictionary

  • dry sump — noun A type of engine sump where oil that flows down from the crankshaft etc is sucked up into an external reservoir (as opposed to a wet sump where it simply pools in a pan at the bottom of the engine) …   Wiktionary

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