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Diagnose Oil Pump 诊断油泵
by Larry Carley copyright AA1Car.com作者：Larry Carley 版权所有 AA1Car.com
The oil pump supplies oil to lubricate your engine. If the oil pump is worn or is not turning, the engine will suffer a loss of oil pressure, which may result in engine damage or engine failure.
油泵提供油来润滑发动机。如果油泵磨损或不转动，发动机将遭受油压损失，这可能导致发动机损坏或发动机故障。
The first sign of trouble may be a low oil pressure warning light, a drop in the normal reading on you oil pressure gauge (if your car has one), or the appearance of ticking or clattering sounds from your engine.
出现问题的第一个迹象可能是低油压警告灯、油压表（如果您的汽车有的话）上的正常读数下降，或者发动机发出滴答声或咔嗒声。
As a rule, most engines only need about 10 PSI of oil pressure for every 1,000 RPM of engine speed. Oil pressure will read higher than normal when a cold engine is first started because the oil is thick. Oil pressure will gradually drop as the engine warms up and the oil thins out. So normal oil pressure on a warm engine cruising down the highway is typically 30 PSI up to 45 PSI.
一般来说，大多数发动机每 1,000 RPM 转速只需要约 10 PSI 的油压。当冷发动机首次启动时，由于机油较稠，机油压力读数会高于正常值。随着发动机升温和机油变稀，机油压力会逐渐下降。因此，在高速公路上行驶的热发动机的正常油压通常为 30 PSI 至 45 PSI。
If your oil warning light is on or your oil pressure gauge is reading low, the first thing you should do is stop your car, turn the engine off, let it sit for a few minutes, then check the oil level on the dipstick. If the oil level is at or below the ADD line, add a quart of oil to bring the level back up to the full mark. Add as much oil as is needed to raise the level to the full mark. Then restart the engine. If the warning light remains on, or the oil pressure reading does not climb back up to its normal range, or the engine noise does not go away, you may have a bad oil pump.
如果您的机油警告灯亮起或机油压力表读数较低，您应该做的第一件事就是停车，关闭发动机，让它静置几分钟，然后检查量油尺上的机油油位。如果油位处于或低于 ADD 线，请添加一夸脱油以使油位回到满刻度。添加所需量的油，将油位升至满刻度。然后重新启动发动机。如果警告灯仍然亮起，或者油压读数没有回升到正常范围，或者发动机噪音没有消失，则油泵可能有故障。
The other possibilities include a bad oil pressure sending unit, or a problem with the oil pressure warning light circuit or oil pressure gauge.
其他可能性包括油压发送单元不良，或油压警告灯电路或油压表出现问题。
If the engine is NOT making any unusual noises and seems to be running normally, and the oil level on the dipstick is FULL, but you are still getting a low oil pressure warning light or low gauge reading, the fault could be a bad oil pressure sending unit.
如果发动机没有发出任何异常噪音并且似乎运行正常，并且量油尺上的油位已满，但您仍然看到低油压警告灯或低仪表读数，则故障可能是油压不良发送单位。
The oil pressure sending unit is mounted on the engine block. On some applications, there is a spring-loaded pressure-sensitive diaphragm with a switch inside the sending unit. This switch completes the circuit to the low oil pressure warning light if oil pressure drops below a certain threshold. The unit may stop working if the diaphragm inside fails, if the switch is stuck, if the small hole that allows oil to enter the sending unit becomes plugged, if there is a loose, corroded or broken wiring connector at the sending unit, or there is a fault in the wiring circuit between the sending unit and warming light.
油压发送装置安装在发动机缸体上。在某些应用中，发送单元内有一个弹簧加载的压敏隔膜和一个开关。如果油压低于某个阈值，该开关会完成低油压警告灯的电路。如果内部隔膜出现故障，如果开关被卡住，如果允许油进入发送单元的小孔被堵塞，如果发送单元上的接线连接器松动、腐蚀或损坏，或者发送单元和加热灯之间的接线电路出现故障。
On vehicles that have an oil pressure gauge (electronic, not mechanical), the oil pressure sending unit has a small rheostat inside that sends a variable voltage signal to the oil pressure gauge when the diaphragm moves. A worn spot on the rheostat or any of the other problems just described for the simple pressure-type oil pressure switches can cause a problem.
在配备机油压力表（电子而非机械）的车辆上，机油压力发送单元内部有一个小型变阻器，当膜片移动时，该变阻器会向机油压力表发送可变电压信号。变阻器上的磨损点或刚才针对简单压力型油压开关描述的任何其他问题都可能导致问题。
On many Ford vehicles that were built from 1980 through the 1990s, the oil pressure sending unit has two switches, a low pressure and a high pressure. These vehicles also have an oil pressure gauge, but the reading on the gauge is not a true indication of real oil pressure. As long as the pressure to the sending unit is between high and low, the gauge will read normal. If oil pressure drops and trips the low pressure switch, the dash gauge will now read low. Or, if oil pressure goes up and trips the high switch inside the sending unit, the dash gauge will read high. Consequently, don't rely on the oil pressure gauge for an accurate reading in these vehicles. It is only a gross indication if the oil pressure is low, normal or high.
在 1980 至 90 年代生产的许多福特汽车上，油压发送装置有两个开关：低压和高压。这些车辆还配有机油压力表，但压力表上的读数并不能真实指示真实机油压力。只要发送单元的压力在高和低之间，压力表读数就会正常。如果油压下降并使低压开关跳闸，则仪表板的读数将变低。或者，如果油压升高并触发发送单元内的高位开关，则仪表读数将很高。因此，不要依赖这些车辆的油压表来获得准确的读数。这只是油压低、正常或高的粗略指示。
If the engine is NOT making any unusual noises and seems to be running normally, the oil level on the dipstick is FULL, and you have replaced the oil pressure sending unit but are still getting a low oil pressure reading on the dash gauge, the fault could be in the wiring circuit between the sending unit and gauge, or the gauge itself might be bad.
如果发动机没有发出任何异常噪音并且似乎运行正常，量油尺上的油位已满，并且您已经更换了油压发送单元，但仪表板上的油压读数仍然较低，则故障可能是在发送单元和仪表之间的接线电路中，或者仪表本身可能是坏的。
Check the wiring connections on both ends as well as wiring continuity between the sending unit and gauge. If no wiring faults are found, hook up a pressure gauge directly to the oil pressure port on the engine and check oil pressure with the engine running. If the engine-mounted gauge shows normal oil pressure but the dash gauge is reading low, the problem is a bad dash gauge.
检查两端接线以及发送单元和仪表之间的接线连续性。如果未发现接线故障，请将压力表直接连接到发动机上的油压端口，并在发动机运转时检查油压。如果安装在发动机上的仪表显示正常油压，但仪表板读数较低，则问题是仪表板损坏。
On the other hand, if the engine-mounted pressure gauge reads low and you have done all of the above, chances are the oil pump is worn, or it is not picking up enough oil because of a restriction or blockage in the pickup screen in the bottom of the crankcase.
另一方面，如果安装在发动机上的压力表读数较低，并且您已完成上述所有操作，则可能是油泵已磨损，或者由于油泵滤网的限制或堵塞而无法吸取足够的油。曲轴箱底部。
The pickup tube has a screen on the end to prevent large chunks of anything bad that ends up in the crankcase from being sucked into the pump. But we are talking BIG chunks of debris, not normal wear particles or carbon or dust or other microscopic-sized abrasive particles that can cause pump wear over time.
吸油管末端有一个滤网，可防止曲轴箱中的大块有害物质被吸入泵中。但我们谈论的是大块碎片，而不是正常的磨损颗粒或碳或灰尘或其他微观尺寸的磨料颗粒，这些颗粒随着时间的推移可能会导致泵磨损。
The only way to inspect the pickup tube is to remove the oil pan from the engine. If the tube is clogged or full of sludge, replace it. Trying to clean out the tube and screen is very difficult as debris can remain trapped inside and out of sight.
Most people don't know that the oil pump is the only engine component that is lubricated with unfiltered oil.
Remember, the oil filter is AFTER the pump, so the oil the pump sucks up from the crankcase is totally unfiltered (except for the relatively coarse pickup screen mentioned earlier).
Consequently, if the oil is not maintained very well, or the vehicle operates in dirty, dusty environment, or the pistons and cylinders are worn and allow a lot of blowby into the crankcase,
the oil pump will wear at an accelerated rate.
大多数人不知道油泵是唯一用未经过滤的油润滑的发动机部件。请记住，机油滤清器位于泵之后，因此泵从曲轴箱吸出的机油完全未经过滤（除了前面提到的相对较粗糙的滤油器滤网）。因此，如果机油保养不好，或者车辆在肮脏、多尘的环境中运行，或者活塞和气缸磨损并导致大量窜气进入曲轴箱，机油泵就会加速磨损。
The tolerances inside most stock production oil pumps are not very close, so one pump's flow may vary as much as 20% to the next. Even so, it's usually more than good enough for a stock engine.
大多数库存生产油泵的公差都不是很接近，因此一台泵的流量可能与下一台泵的流量相差 20%。即便如此，对于普通发动机来说，它通常已经足够好了。
If the gears inside the oil pump are worn, or there are excessive clearances between the gears and pump housing, or the housing or end plate are worn, the pump will leak pressure internally and may not deliver as much oil flow to the engine as it did when it was new.
如果油泵内的齿轮磨损，或者齿轮与泵壳之间的间隙过大，或者泵壳或端板磨损，泵将内部泄漏压力，并且可能无法向发动机输送尽可能多的油流量。当它是新的时候做的。
The rotating gears inside the oil pump siphon oil from the crankcase through a pickup tube into the pump. The gears then push the oil through the pump and out the discharge port. From here, the oil goes to the oil filter. If the oil is really cold and thick, the bypass valve on the oil filter will open and allow unfiltered oil to bypass the filter. This is necessary so a cold engine will still develop normal oil pressure until it warms up and the oil thins out.
油泵内的旋转齿轮将曲轴箱中的油通过吸油管吸入泵中。然后齿轮将油推过泵并从排出口流出。油从这里进入油过滤器。如果机油确实又冷又稠，机油滤清器上的旁通阀将打开，让未过滤的机油绕过滤清器。这是必要的，这样冷发动机仍会产生正常的油压，直到它变暖并且油变稀。
The three basic types of oil pumps include:
* Twin gear pumps, where one gear is connected to a shaft that is driven off the camshaft or distributor. This type of pump is usually mounted inside the oil pan on the bottom of the engine block. The pump usually turns at half engine speed.
* Gerotor pumps that have a small gear rotating inside a larger outer gear. This type of pump can also be mounted on the bottom of the engine inside the oil pan.
* Internal pumps, which are usually mounted inside the front engine cover and are driven by the crankshaft. The gear design is usually a gerotor style, but this type of pump turns at the same RPM as the engine. Thus, it can generate more flow and oil pressure. This design is often used on overhead cam engines.
As mentioned earlier, the only way to know for sure if an oil pump is generating normal pressure is to remove the sending unit on the engine block, and screw-in a mechanical oil pressure gauge. If the gauge does not show normal oil pressure, the pump is bad, or the pickup tube is blocked.
There is no way to easily bench test an oil pump to see if it is good or bad. To get an accurate indication of flow, you would have to simulate the resistance the pump sees inside an actual engine, and have a highly accurate gauge that can measure glow in gallons per minute. Oil pump manufacturers have their own custom test equipment that can bench test the flow characteristics of their oil pumps, but this type of equipment is not available to repair shops or anyone else.
About all you can do is disassemble your oil pump and look for obvious signs of wear or damage. With oil pumps mounted inside the bottom of the engine, this requires removing the oil pan. With oil pumps mounted inside the front engine cover, it requires tearing everything off the front of the engine and removing the cover. Both can be a big, expensive jobs!
Internal oil pump clearance specifications vary depending on the type of pump and the manufacturer, but minimal clearances are essential for good flow and oil delivery. Feeler gauges can be used to check the clearance between the gears, between the gears and housing, and between the tops of the gears and the cover. If clearances exceed specifications, the pump is worn or has sloppy assembly tolerances and needs to be replaced.
With twin-gear type pumps, it is possible to block sand or machine down the face of the pump housing to reduce the clearance between the tops of the gears and the pump cover. The flow characteristics of the pump can also be improved by gently rounding and blending the inlet and outlet ports inside the housing to eliminate sharp edges. Some high performance oil pumps have additional slits and slots to control internal lubrication and to eliminate cavitation that can disrupt oil flow at higher engine speeds.
If you are replacing an oil pump with a new one, make sure it is the correct pump for your engine. A pump that does not have sufficient flow capacity may starve the engine for oil. On engines where the pump bolts up against the bottom of the block, there may or may not be a gasket or o-ring between the pump housing and engine. This can be a leak path for oil pressure, so make sure the gasket or seal is installed properly. If there is no gasket, some aftermarket suppliers now make thin copper gaskets that can be installed between the pump and engine to prevent pressure losses.
With crankcase mounted oil pumps, don't reuse the old oil pan gaskets even if they are rubber rather than cork or fiber. Install new gaskets for a leak-free seal.
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