Oil system vent with remote oil reservoir

Abstract

The invention includes an oil system vent that is remote from an oil reservoir so that the oil reservoir can be stored in the bilge section of a boat. The oil reservoir has an oil supply outlet and an oil supply return. The oil reservoir is constructed without a ventilation means attached thereto. The oil system vent includes an oil return port having an oil input and an oil output. The oil input receives pressurized lubricant and the oil output returns the pressurized lubricant to the oil supply return of the oil reservoir. The oil return port has a vent port in communication with atmospheric pressure so that when lubricant is drawn and used from the oil reservoir, the vent port allows air to displace the used lubricant in the oil reservoir. The oil reservoir is positioned at a relatively low elevation, in the bilge section of the boat, and the vent port is positioned at a relatively high elevation with respect to the outboard motor.

Description

BACKGROUND OF THE INVENTION

The present invention relates generally to oil systems for internal combustion engines, and more specifically, to an oiling system for a two-stroke engine in an outboard motor having an oil reservoir remote from the oil system vent.

Typically, two-stroke outboard marine engines do not have a separate oiling system. That is, these prior art engines require pre-mixing lubricant and fuel so that the lubricant dissolves in the fuel to lubricate the engine. This requires consistent, accurate measuring and agitation of the mixture. There are many disadvantages to the prior art system of pre-mixing lubricant and fuel. For example, since various two-stroke engines require different mix concentrations, many outboard marine engine owners also own other two-stroke engine equipment, such as various lawn and garden equipment and ATV's, they may store several different concentrations of oil/fuel mixture. This is not only an aggravation to the owner, but is also problematic if the containers become mixed up and the owner uses the wrong concentration for a particular two-stroke engine. While this is not catastrophic, if run over time with the wrong concentration, a two-stroke engine can wear excessively.

The present invention is for use in a unique lubrication system for two-stroke engines. Such a lubrication system must provide lubrication to each cylinder of the engine and provide lubrication to the fuel system to properly lubricate the fuel metering and injection system from an oil reservoir.

It is desirable in such systems to place the oil reservoir in the bilge section of the boat. However, since such prior art oil reservoirs have a vent located directly on the oil reservoir, and often in the cap on the top of the reservoir, water in the bilge section of the boat can be ingested into the tank through the vent. That is, as oil in the tank is consumed, the volume must be displaced, and is usually displaced with air from the vent. While occasionally the oil reservoir may become submerged in water and the water can be directly ingested into the oil reservoir by the vacuum created by the oil consumed, water may also be consumed if the oil reservoir is not completely submerged, but only subjected to the normal use of the boat in which water splashes on the oil reservoir thereby allowing ingestion of air and water. Since water will sink to the bottom of the tank and the oil will float on top of the water due to their relative densities, and since oil is often drawn from the bottom of the tank to maximize volume of the tank, the oiling system can draw water in place of oil if the water level reaches the oil pickup. Water in place of oil, or water mixed with oil, can severely damage an engine.

It would therefore be desirable to have an oiling system that could accommodate a completely sealed oil reservoir that may be located in the bilge of the boat, and may be susceptible to complete submersion.

SUMMARY OF THE INVENTION

The present invention includes a ventless oil reservoir and a remote oil system vent for an outboard motor that solves the aforementioned problems.

In accordance with one aspect of the invention, an oil system vent for an outboard motor includes an oil reservoir having an oil supply outlet and an oil supply return. The oil reservoir is designed to be located below the water line of a boat, and in particular, in the bilge area of the boat. The oil reservoir is free of any internal ventilation means such that the oil reservoir can be completely submerged in water, and as long as the cap is secured tightly, water will not enter the oil reservoir, even when the oil reservoir is under a slight vacuum. The oil system vent includes an oil return port having an oil input and an oil output. The oil input receives pressurized lubricant and the oil output and returns the pressurized lubricant to the oil supply return of the oil reservoir. The oil return port also has a vent port that is in communication with atmospheric pressure when lubricant is drawn and used from the oil reservoir. In this manner, the vent port allows air to displace the used lubricant in the oil reservoir.

In accordance with another aspect of the invention an oil system for a two-stroke engine includes a ventless oil reservoir having a pump associated therewith to draw and pump lubricant therefrom. A closed loop in an oil routing system of the oiling system includes the ventless oil reservoir and pump, and also includes a pressure regulator and a solenoid valve. The solenoid valve is positioned in the closed loop to periodically open the closed loop and divert lubricant to the two-stroke engine. A remotely located vacuum controlled vent valve is located in the closed loop to allow air into the closed loop when the solenoid valve periodically diverts lubricant to the two-stroke engine.

Another aspect of the invention includes a boat and outboard motor combination that includes an outboard motor mounted to the transom of a boat and further includes a ventless oil reservoir located in the boat that does not allow water ingestion even when completely submersed in water. The combination includes an oiling system having a pump to draw lubricant from the ventless oil reservoir and route the lubricant through the oiling system and back to the ventless oil reservoir. The oiling system periodically diverts the lubricant to the engine of the outboard motor. The combination also includes a remote ventilation means for venting the ventless oil reservoir while lubricant is periodically diverted to displace used lubricant with air to avoid excessive vacuum in the oil reservoir.

The invention also includes a method of venting an oil reservoir of an outboard motor that includes providing a ventless oil reservoir and routing lubricant from the ventless oil reservoir through an oil pump, to an oil system, and back to the ventless oil reservoir in a closed loop. The method includes periodically opening the closed loop in the oil system to draw and use lubricant from the ventless oil reservoir. A vent valve is provided at a higher elevation than the ventless oil reservoir. The vent valve automatically opens when lubricant is consumed to displace the consumed lubricant with air within the ventless oil reservoir.

Various other features, objects and advantages of the present invention will be made apparent from the following detailed description and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate one preferred embodiment presently contemplated for carrying out the invention.

In the drawings:

FIG. 1 is a perspective view of an oiling system for a two-stroke outboard marine engine.

FIG. 2 is a schematic illustration of an oiling system in accordance with one aspect of the present invention.

FIG. 3 is a left side, elevational view of the oiling system of FIG. 1 connected to an ECU of an outboard motor.

FIG. 4 is a front elevational view of the oiling system of FIG. 1 shown connected to an ECU and oil tank for an outboard motor.

FIG. 5 is a top plan view of the oiling system of FIG. 4 .

FIG. 6 is a partial cross-section of the oiling system taken along line 6 — 6 of FIG. 5 .

FIG. 7 is a cross sectional view taken along line 7 — 7 of FIG. 5 .

FIG. 8 is a partial cross-sectional view taken along 8 — 8 of FIG. 5 .

FIG. 9 is a partial cross-sectional view taken along line 9 — 9 of FIG. 5 .

FIG. 10 is a partial cross-sectional view taken along line 10 — 10 of FIG. 5 .

FIG. 11 is a partial cross-sectional view taken along line 11 — 11 of FIG. 4 .

FIG. 12 is a schematical illustration of the oiling system shown in FIGS. 1-10 incorporated into an outboard motor and boat combination.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1 , an oiling system 10 is shown, preferably for a two-stroke engine of an outboard marine motor. The oiling system 10 includes an oil system housing 12 having an oil inlet 14 connected to a supply line 16 . The oiling system housing 12 also includes an oil outlet 18 that supplies oil to a distribution manifold 20 . A separate oil return 22 is provided through a tee-connector 24 connected to the oil system housing 12 and a return line 26 to return unused oil to an oil reservoir. The tee-connector is also connected to a vent valve 28 that is open on one end 30 to atmospheric pressure.

The oil system housing 12 is mounted to an engine with mounting bolts 32 , 34 and is constructed to receive a full flow, replaceable oil filter 36 on an oil filter base 38 to filter incoming pressurized oil from supply line 16 through oil inlet 14 . The pressurized oil is then routed through internal passages to an oil flow control section 40 of the oil system housing 12 . The oil flow control section 40 is controlled by a solenoid (not shown in FIG. 1 ) that controls whether oil flows through the oil outlet 18 and distribution manifold 20 or through the oil return 22 and return line 26 . The oil system housing 12 also includes a test port 48 that is in fluid communication with an output side of the replaceable oil filter 36 to measure oil pressure during operating conditions. The housing 12 also includes a sensor chamber 42 to receive an oil pressure sensor 64 therein.

Referring to FIG. 2 , a schematic representation of an oiling system 10 in accordance with the present invention is illustrated. The oil system includes an oil tank/reservoir 50 having an oil pump 52 associated therewith to pump oil through supply line 16 and filter 36 . In a preferred embodiment, as shown in FIG. 2 , the oil pump 52 is located inside the oil tank 50 . After the oil is filtered, it is routed through an internal passage 54 of the oil system housing 12 to the oil flow control section 40 wherein the flow of oil is controlled by operation of solenoid 44 , which in turn is controlled by an electronic control unit (ECU) 56 . As previously indicated, the solenoid 44 toggles the flow of lubricant from internal passage 54 to internal passages 58 and 60 . When the solenoid 44 is not activated, the normally open position 61 relays oil from the internal passage 54 to the internal passage 60 of the oil system housing 12 through an internal pressure regulator 62 and returns unused oil to the oil reservoir 50 .

When solenoid 44 is activated, the flow of oil is diverted to internal passage 58 to supply oil to the distribution manifold 20 . A pressure sensor 64 is in fluid communication with the lubricant in internal passage 58 to monitor the lubricant pressure and provide an oil pressure signal 66 to the ECU 56 . The distribution manifold 20 includes an internal check valve 68 to prevent the backflow of oil in the oil system 10 . The distribution manifold 20 has a number of cylinder oiling outlets 70 that coincide with a number of cylinders of an engine 72 , and each oiling outlet 70 is connected to a cylinder of engine 72 . The distribution manifold 20 also includes a fuel system oiling outlet 72 to supply lubricant to the fuel system 74 , preferably, to lubricate a fuel injection distribution system, and purge air from the oil system through a fuel separator in the fuel system 74 .

The oil reservoir 50 of oil system 10 includes an oil supply outlet 76 and an oil supply return 78 and is free of any internal ventilation mechanism. In this manner, the oil reservoir 50 can be completely submerged in water, and as long as the fill cap is properly closed, water cannot enter the oil reservoir.

When solenoid 44 is not activated, a closed loop 80 is formed in the oil routing system between the ventless oil reservoir 50 , the filter 36 , the oil flow control section 40 , through internal passage 60 , and the oil return 22 . As long as no oil is withdrawn from the reservoir, by the activation of solenoid 44 , the oil circulates through the closed loop 80 . However, when the loop is open by solenoid 44 to divert lubricant from internal passage 60 to internal passage 58 in the oil flow control section 40 , oil is then consumed in the engine 72 and the fuel system 74 . This consumption of oil must be displaced or the oil reservoir 50 will come under an increasing negative pressure. Accordingly, the vent valve 28 is coupled to the closed loop 80 at one end of the tee-connector 24 at the oil return 22 . Vent valve 28 is a vacuum controlled vent valve and includes a check valve 82 that preferably opens at approximately 3″ of H 2 O to allow air to displace the consumed oil in the oil reservoir 50 when the solenoid valve 44 periodically diverts lubricant to engine 72 . The vent valve 28 also includes a filter 84 to filter contaminates that may be drawn from the atmosphere 86 .

Accordingly, a method of venting an oil reservoir 50 of an outboard motor is disclosed that includes providing a ventless oil reservoir, routing lubricant from the ventless oil reservoir 50 through an oil pump 52 , to an oil system 10 and back to the ventless oil reservoir 50 in a closed loop 80 . The method includes periodically opening the closed loop 80 in the oil system 10 to draw unused lubricant from the ventless oil reservoir. The method also includes providing a vent valve 28 , remote from the ventless oil reservoir 50 , and at an elevation higher than that of the ventless oil reservoir. The vent valve then automatically opens when lubricant is consumed to displace the consumed lubricant with air in the ventless oil reservoir.

Referring to FIG. 3 , a left side view of the oil system 10 and the oil system housing 12 of FIG. 1 shows the ventilation system 88 , the distribution manifold 20 , and the solenoid 44 and the pressure sensor 64 connected to the ECU 56 by lead wires 45 , 65 . The distribution manifold 20 is mounted to the housing 12 over the oil outlet 18 by mounting bolts 90 . When oil is diverted by solenoid 44 , it is routed through oil outlet 18 to a plurality of cylinder outlet housings 92 and a fuel system oiling outlet housing 94 , each of which is equipped with a push-to-connect fitting 96 to allow quick connection and disconnection of the oiling lines that extend to each cylinder and the fuel system. As is indicated in FIG. 3 , the fuel system oiling outlet housing 94 is at a higher elevation than each of the cylinder oiling outlets 92 to purge any air from the oiling system through a fuel separator in the fuel system.

The ventilation system 88 preferably includes a diaphragm vent valve 28 . The vent valve 28 includes two ends 98 , 100 , wherein a first end 98 is in communication with the oil return 22 via the tee-connector 24 of the oil system housing 12 . The second end 100 is open to the atmosphere 86 to draw air therefrom when solenoid 44 is activated by ECU 56 .

FIG. 4 shows a front elevational view of the oiling system 10 of FIG. 1 connected schematically to the closed loop default flow path 80 . As indicated, lubricant is pumped from the oil reservoir 50 by pump 52 and circulates through the closed loop system 80 all the while that solenoid 44 is not activated by the ECU 56 , which also controls the oil pump 52 . In this manner, oil is circulated from the oil reservoir 50 through the oil inlet 14 , through the replaceable oil filter 36 and is routed in the oil flow control section 40 to the oil return 22 , out the tee-connector 24 , and back to the oil reservoir 50 . When the solenoid 44 is activated by the ECU 56 , oil is then diverted from the oil return 22 to the oil outlet 18 and out the distribution manifold 20 to each of the engine cylinders and the fuel system. As oil is consumed, the oil reservoir comes under a negative pressure and draws air through the ventilation system 88 .

According to one aspect of the invention, the aforementioned system is incorporated into a two-stroke engine of an outboard motor that includes the oil system housing 12 having an oil filter base to replaceably receive an oil filter 36 thereon such that lubricant in the closed loop system 80 can be continuously filtered, and filtered before consumption by the two-stroke engine.

FIG. 5 shows a top plan view of the oiling system 10 of FIGS. 1 , 3 and 4 . FIG. 5 shows a top view of the distribution manifold 20 and the diaphragm vent valve 28 . FIG. 5 is used to illustrate the cross-section views for FIGS. 6-10 that illustrate the oil flow paths through housing 12 .

Referring to FIG. 6 , oil is first introduced into the oil inlet port 14 through a first internal passage 102 and is then introduced into the full flow, replaceable oil filter 36 . The oil filter is mounted to the oil filter base 38 and sealed therebetween with gasket 104 . Oil is introduced into filter 36 through a plurality of openings 106 , is filtered in element 108 and discharged through center opening 110 . As shown in FIG. 7 , once discharged through center opening 110 , the oil enters a second internal passage 112 and is routed to the oil flow control section 40 .

The test port 48 is in fluid communication with the second internal passage 112 and is equipped with a Schraeder valve 114 to test the oil pressure on the back side of filter 36 . The Schraeder valve 114 thus provides a point to acquire an accurate reading of the oil pressure as it is presented through the system.

As indicated by arrow 116 , oil is then routed to a third internal passage 118 when solenoid 44 is not activated. Solenoid 44 includes an internal plunger 120 , magnet 122 and return spring 124 and is constructed in a known manner. The oil flow control section 40 includes a check ball 126 and a pressure spring 128 which moves downwardly when the solenoid is activated, which pulls plunger 124 downwardly and closes the oil path indicated by arrow 116 when oil is diverted to the engine.

Referring now to FIG. 8 , the return oil path through solenoid 44 is shown. The oil return port 22 , which includes the tee-connector 24 , is in fluid communication with the third internal passage 118 through a pressure regulator 62 . The pressure regulator 62 includes a check ball 130 and pressure spring 132 to regulate the oil pressure in the oil system at a desired level. The tee-connector 24 includes a relatively narrow air inlet passage 134 that is connected with a hose 136 to the vent valve 28 . The vent valve 28 includes air filter 84 and check valve 82 , which in turn includes a diaphragm 138 and return spring 140 . The vent valve 28 is connected to an L-shaped extension hose 142 at its second end 100 to draw air from the atmosphere 86 to displace consumed oil, as previously described. FIG. 8 also shows a more detailed view of solenoid 44 in which plunger 120 is drawn downward when the magnet 122 is energized. The return spring 124 , which is positioned between a stationary block 144 and a shoulder 146 of the plunger 120 , causes the plunger to return to its upward position when the magnet 122 is de-energized. An extension shaft 148 is positioned within the plunger 120 and extends upward to support the check ball 126 against pressure spring 128 to maintain oil flow around the check ball 126 along the third internal passage 118 .

FIG. 9 shows the solenoid 44 in its actuated position with the plunger 120 drawn downwardly within the magnet 122 . In this position, the return spring 124 is compressed and the pressure spring 128 is extended causing the check ball 126 against seat 150 which closes oil flow through the third internal passage 118 . In this position, oil is routed through a fourth internal passage 152 , which is in communication with the pressure sensor 64 . Pressure sensor 64 is threadedly engaged in housing 12 and is constructed in a known manner having a pressure diaphragm 154 connected to a pair of contacts 156 that operate to close an electrical path between contact leads 158 which are connected to the ECU. The fourth internal passage 152 is also in fluid communication with the oil outlet 18 of FIG. 10 to supply oil to a number of passages 160 in the distribution manifold 20 to supply oil to the cylinder outlet housings 92 and then to each cylinder of the two-stroke engine. Oil is also supplied by oil outlet 18 to passage 162 , FIG. 9 , to supply oil through the fuel system oiling outlet housing 94 which leads to the fuel system. Internal passage 162 is at the highest point to purge any air from the oil system.

FIG. 11 shows a cross-section of the distribution manifold 20 taken along line 11 — 11 of FIG. 4 showing the distribution manifold mounted to the oil system housing 12 . The cross-section shows oil outlet 18 opening into a D-shaped domed chamber 166 that feeds oil to each of the passages 160 equally. Each of the passages 160 include a check valve 164 within the cylinder outlet housings 92 , and each of the outlet housings 92 include a push-to-connect fitting 96 , such as the Legris Carstick® fitting made by Legris, Inc. Since the fuel system outlet housing 94 is at a higher elevation than the other outlet housings 92 , the upper passageway is not shown. However, passageway 162 for the fuel system outlet housing 94 is at the highest elevation to intersect with a high point of the dome chamber 166 . As previously described, this allows any air in the oil system to purge through outlet housing 94 which leads to the fuel system, and once in the fuel system, the air is purged through a fuel separator.

FIG. 12 shows an operating environment for the present invention herein described. However, it will be appreciated by those skilled in the art that the present invention is equally applicable for use with other types of engines and applications. FIG. 12 shows an outboard motor 170 having a power head 172 enclosed in an upper cowl 173 , a midsection 174 , and a lower gear case 176 . The outboard motor 170 is mounted to a transom 178 of a boat 180 by a transom mounting bracket 182 . The outboard motor 170 includes a propeller 184 extending rearward from the lower gear case 176 to propel the boat 180 through the water. The powerhead 172 includes a two-stroke internal combustion engine 186 controlled by the ECU 56 . A fuel tank 188 supplies fuel to the fuel system 190 through a pickup line 192 , as is known.

As described with reference to FIG. 2 , the oil reservoir 50 pumps oil via pump 52 to the inlet 14 and after filtering through filter 36 , the oil is re-circulated through the closed loop 80 until the solenoid 44 is activated by the ECU 56 which diverts lubricant to each of the cylinders 194 and the fuel system 190 . As lubricant is withdrawn and consumed from the oil reservoir 50 , vent 28 cracks open to intake air and displace the oil consumed in the reservoir 50 . Preferably, the oil reservoir is located in a bilge section 196 of the boat 180 , which is below the water line 198 . It is also preferred that the open end 30 of the vent valve 28 is at an elevation well above the water line 198 to avoid the introduction of water into the oil reservoir 50 .

Accordingly, the present invention also includes a method of venting an oil reservoir of an outboard motor that includes providing a ventless oil reservoir, routing lubricant from the ventless oil reservoir through an oil pump to an oil system, and back to the ventless oil reservoir in a closed loop. The method next includes periodically opening the closed loop in the oil system to draw and use lubricant from the ventless oil reservoir. The method provides a vent valve remote from the ventless oil reservoir at an elevation higher than that of the ventless oil reservoir. The vent valve automatically opens when lubricant is consumed to displace the consumed lubricant with air in the ventless oil reservoir.

The present invention has been described in terms of the preferred embodiment, and it is recognized that equivalents, alternatives, and modifications, aside from those expressly stated, are possible and within the scope of the appending claims.

Claims

1. An oil system vent for an outboard motor comprising:an oil reservoir having an oil supply outlet and an oil supply return, the oil reservoir free of an internal ventilation mechanism; and; an oil return port having an oil input and an oil output, the oil input receiving pressurized lubricant and the oil output returning the pressurized lubricant to the oil supply return of the oil reservoir, the oil return port also having a vent port remote from the oil reservoir and in communication with atmospheric pressure such that when lubricant is drawn and used from the oil reservoir, the vent port allows air to displace used lubricant.

2. The oil system vent of claim 1 wherein the oil reservoir is positioned at a relatively low elevation with respect to the outboard motor and the oil return port is positioned at a relatively high elevation with respect to the outboard motor.

3. The oil system vent of claim 1 wherein the oil return port is locatable within a cowling of the outboard motor and the oil reservoir is locatable within a boat that the outboard motor is mounted thereto.

4. The oil system vent of claim 1 further comprising a check valve located between the vent port of the oil return port and atmospheric pressure.

5. The oil system vent of claim 4 wherein the check valve is a diaphragm valve having a cracking pressure of 3″ H2O.

6. The oil system vent of claim 4 wherein the check valve includes a filter between the check valve and atmospheric pressure to filter incoming air.

7. The oil system vent of claim 1 further comprising and connected to an oil system housing having a solenoid to periodically divert lubricant from the oil input of the oil return port and route lubricant to a two-stroke engine.

8. The oil system vent of claim 7 further comprising:a check valve located between the vent port of the oil return port and atmospheric pressure; and when lubricant is routed to the two-stroke engine, the check valve momentarily opens due to a negative pressure in the oil reservoir caused by lubricant use by the two-stroke engine thereby allowing air to displace dispensed lubricant in the oil reservoir.

9. The oil system vent of claim 7 further comprising an oil distribution manifold in fluid communication with an oil passage of the oil system housing to receive the periodically diverted lubricant and to route the periodically diverted lubricant to each cylinder of the two-stroke engine.

10. The oil system vent of claim 9 wherein the distribution manifold includes a fuel system oiling outlet and a plurality of cylinder oiling outlets and wherein the fuel system oiling outlet is at an elevation higher than that of each of the cylinder oiling outlets.

11. The oil system vent of claim 1 wherein the outboard motor includes a two-stroke engine and a full-flow replaceable oil filter between the oil reservoir and the oil return port.

12. An oiling system for a two-stroke engine comprising:a ventless oil reservoir having a pump associated therewith to draw and pump lubricant therefrom; a closed loop in an oil routing system having therein the ventless oil reservoir and pump and further having a pressure regulator and a solenoid valve; the solenoid valve positioned in the closed loop to periodically open the closed loop and divert lubricant to the two-stroke engine; and a vent valve located in the closed loop to allow air into the closed loop when the solenoid valve periodically diverts lubricant to the two-stroke engine.

13. The oil system of claim 12 incorporated into an outboard motor and wherein the ventless oil reservoir is located below a water line and the vacuum controlled vent valve is located in an upper cowling of the outboard motor.

14. The oil system of claim 13 further comprising an oil distribution manifold in fluid communication with an oil passage in the closed loop of the oil routing system to receive the periodically diverted lubricant and to route the periodically diverted lubricant to each cylinder of the two-stroke engine when the solenoid valve is activated.

15. The oiling system of claim 12 wherein the vent valve is vacuum controlled and includes a diaphragm valve with one end positioned in the closed loop and another end open to atmospheric pressure.

16. The oil system of claim 13 further comprising a replaceable oil filter in the oil routing system.

17. A boat and outboard motor combination comprising:a boat having a transom with an outboard motor mounted thereto; a ventless oil reservoir located in the boat and susceptible to water submersion; an oiling system having a pump to draw lubricant from the ventless oil reservoir and route the lubricant through the oiling system and back to the ventless oil reservoir and periodically divert the lubricant to an engine in the outboard motor; and a ventilation means on the outboard motor for venting the ventless oil reservoir while lubricant is periodically diverted.

18. The combination of claim 17 wherein the ventilation means is located in an upper cowling of the outboard motor.

19. The combination of claim 17 wherein the ventilation means includes a check valve and a filter positioned in a return path of the oil system.

20. The combination of claim 19 wherein the check valve is a diaphragm check valve with a cracking pressure of 3″ H2O.

21. A method of venting an oil reservoir of an outboard motor comprising:providing a ventless oil reservoir; routing lubricant from the ventless oil reservoir through an oil pump, to an oil system and back to the ventless oil reservoir in a closed loop; periodically opening the closed loop in the oil system to draw and use lubricant from the ventless oil reservoir; and providing a vent valve remote from the ventless oil reservoir and at an elevation higher than that of the ventless oil reservoir, the vent valve automatically opening when lubricant is consumed to displace the consumed lubricant with air in the ventless oil reservoir.

22. The method of claim 21 further comprising the step of placing the ventless oil reservoir in an area susceptible to water submersion.

23. The method of claim 21 further comprising the step of placing the ventless oil reservoir in a bilge section of a boat.