Engine Oiling Systems part4

OIL FILTERS

All cars are now fitted with full flow oil filters as standard equipment. As stated earlier, these are located in the lubrication system immedia tely after the oil pump, and before the main bea rings, so that all oil is filtered before “going into a ction.” Pra ctically all of these filters are of the “spin-on” type, which means that the whole filter unit is a throw-away unit. It is screwed onto the engine block by hand pressure only–it must not be overtightened or the rather thin metal case might be distorted, causing leaks.

The filter should be changed at the intervals recommended by the car manufacturer, and to remove it, it may be necessary to use a special filter wrench, as the gasket may have caused it to stick. But never use the wrench to tighten the filter. A useful precaution that helps to prevent the gasket from stieking is to wipe a little engine oil on it with the finger before installing it.

There are two basic types of full flow filters­ the pleated paper type and the depth filtration type. The first makes use of a very large area of specially treated paper as the filtering element. It is pleated in order to get the large area into the limited space of the filter can. This is known as a surfaee type filter because the oil only has a very short travel through the filtering medium.

The depth type uses a cartridge with filter media so arranged that the oil must pass through a relatively large depth of material before leaving the filter. This type is made of any of a number of different materials-soft white cotton thread blended with wood wool; cotton thread and sisal; paper and wood chips; paper and barley hulls. The object is to trap the very fine particles of dirt and pr event them from getting into the engine lubricating system.

It is not possibl e to tell from the outside what materials a filter is mad e of, so it is important that only filters made by r eputabl e manufacturers be used.

Good filtration of the oil is extremely important, especially in mod ern engines which are built with relatively small clearances, and which can be quickly ruin ed by dirty oil. This cannot be too stron gly emphasized, Fig. 32.

Older cars have used several different types of filtration. For example , some have used a by-pass type filter system, others a shunt type.

The by-pass system, as its name implies, bypasses a small quantity of the oil pumped by the engine oil pump through a very fine filter which removes almost all impurities from the oil and then returns the oil to the oil pan. The amount of oil that passes through the filter varies from 5% to 20% of the total, according to the engine. The remaining 80% to 95% of the oil passes unfiltered either to the engine bearings or through the pres­ sure relief valve if the bearings cannot take it all.

Engine protection with this system is uncertain, but oil cleansing is good and service life of the filter is good.

The shunt system-which the by-pass system is sometimes called-is neither full flow nor by-pass, but a combination of both. In this system, oil from the pump is passed into the filter on the way to the bearings, but after entering the filter hous­ ing, it has the option of either passing through the filter cartridge or through an opening around the cartridge. This shunt opening is large enough to handle the entire oil supply to the bearings after the filter becomes completely plugged, but with a pressure drop at the bearings. In actual operation, when the filter cartridge is new, more oil will go through the cartridge than through the shunt passage. This means that the bearings re­ ceive full flow protection according to the per­ centage of oil passing through the cartridge. As the cartridge collects dirt, this percentage will drop until ultimately the full flow protection becomes zero. Since the cartridge handles only a percentage of the bearing supply, it functions somewhat like a by-pass filter even though the ini­tial flow through the cartridge starts out consider­ ably higher than with a by-pass type cartridge.

Another way of describing the shunt system is to say that some of the oil is sidetracked, filtered, and then fed back into the main oil stream. As in the case of the by-pass system, the shunt filter cleans the oil a little at a time , but what it cleans, it cleans very thoroughly. Variations of this system provide the shunt either at the oil pump itself or somewhere between the pump and filter.

There is a fourth type of :6Jter system that is becoming popular on large diesel engines, where engine failure can be very expensive. This is the dual :6Jtration system, in which both full flow and by-pass systems are used together, either by using two separate :6Jters, or by combinin g the two functions in one :6Jter housing. This system pro­ vides what appears to be the ultimate in :6Jtration with the facilities and equipmen t available today.

Older types of :6Jter h ave consisted of a throw­ away type of housing, bu t instead of being a spin­ on type, the housing is held to the engine blo ck or the firewall by a clamp, and the oil connections are made by pipe unions. Another type made u se of a housing like that described above, but the top is removable so that the old cartridge can be removed, the housing cleaned and a new cartridge installed.

Filters fo r High Performance Engines

Competition :6Jters differ from convention al filters in that they are constru cted to withstand m ore severe service. Street type :6Jters use thin wall steel casings which are adequate for aver age pr essure surges. High performance :6Jters are con­ structed of heavy gauge (one third heavie r th an conventional) metal.

The contour of the can is such that no weak points occur during the stamping process, and the can is made to tolerate pressures up to 400 psi. The base plates are similarly constru cted of heavier gauge steel to prevent warpage and oil leakage caused by high pressure surges. The ports in the base plates are designed for maximu m oil flow. Thus oil pressure remains high at high engine speeds.

CRANKCASE VENTILATION

Crankcase ventilation has an important function in controlling sludge and keeping the engine lubricating system in good condition. Ineffective or inoperative crankcase ventilators are respon­ sible for lubricating troubles serious enough in some cases to cause engine failure.

Two methods of crankcase ventilation are in use, the road-draft system and manifold vacuum system, both shown schematically in the same drawing in Fig. 33.

Fig. 5 shows a typical road draft type. As indicated by the direction of the arrows, air is driven into the crankcase by fan draft through a copper gauze :6Jter in the oil filler cap. It then circulates around the inside of the engine and is discharged through the ventilator outlet pipe, carrying with it the water vapor which collects in the crankcase, particularly in cold weather. When­ ever the oiling system is cleaned, the filler and outlet pipes should be removed and flushed out thoroughly. The gauze filters should also be washed in clean gasoline or kerosene.

In order to control smog, the manifold vacuum system of crankcase ventilation is standard equip­ ment on 1961-62 cars to be used in California and is mandatory on all cars starting with 1963 models. The correct operation of this system de­ pends upon a free flow of air from the carburetor air cleaner through the oil filler tube and engine to the control valve mounted on the intake manifold, Fig. 33. The arrows indicate the direction of the flow of air.

The system sucks crankcase vapors into the intake manifold to be burned in the combustion chamber. The flow of the vapors is controlled by the ventilator valve. The valve is actuated by engine vacuum working against spring tension. The high vacuum at engine idle provides mini­ mum ventilation; low vacuum at road speeds pro­ vides maximum ventilation.

Servicing the system consists of checking the valve, the tubing .and the air intake. The valve should be removed and checked for proper opera­ tion and for harmful deposits. If necessary, dis­ assemble the valve, clean the parts in solvent and dry with compressed air. Inspect each component carefully. If the spring is distorted or the valve is worn the valve should be replaced. When reas­ sembling the valve, make sure the end coil of the spring is snapped in the groove which is usually just under the head of the valve.Remove the tubing and blow out any deposits with compressed air. When reinstalling the valve and tubing, make sure all connections are tight to prevent air leaks.

On some engines, the system air intake is hose from the air cleaner to the oil filler tube. Make sure the hose is-in good condition, and all connec­ tions arc air tight. Check the oil filler tube cap to be sure it makes an air tight seal on the tube. Air leaks can easily be checked for by squirting kero­ sene at the connections.

On other engines , th e system air intake is a :6Jter type oil filler tube cap. Check the cap :6Jter to be sure it is free of dirt. Clean it in solvent if nec­ essary.

If the control valve becomes clogged with car­bon or other forei g n matter the ventilation system will not operate and a slight pressure will build up in the crankcase which may cause oil leakage at the rear main bearing or by the piston rings. And should the valve fail to seat it will be impossible to make the engine idle satisfactorily.

If idle speed is slow, unstable, rolling, with frequent stalling; if there is back flow through the crankcase breather (it may be necessary to re­ move the oil filler cap or the air cleaner to see this condition) and if the engine compartment is covered with an oily mist, the ventilator valve, or PCV (Positive Crankcase Ventilation) valve may be completely clogged or stuck in the open position.

A valve stuck in the closed position is also indi­ cated by breather back flow and an oily engine compartment.

If the valve is stuck in the intermediate position, the indication will be a rough fast idle and stalling.

The PCV valve should be cleaned every six months or 6000 miles, whichever comes first, and more frequently when there is a lot of engine idling in cold weather.

When the valve assembly is removed for clean­ ing, place a finger over the open end of the hose or tube and have the engine started. If the hose and carburetor passages are open and operating nor­ mally, a strong suction will be felt and there will be a large change in engine idling quality when the end of the hose is uncovered. If these condi­ tions are not found, the carburetor passages and/or ventilator hose are clogged and must be cleaned or replaced. The carburetor should be removed from the engine and the ventilator pas­ sages cleaned by dipping the lower part of the carburetor in the cleaning fluid. A pipe cleaner or wire can be used to clean the passages.

PCV SYSTEM TESTS

If a condition of rough or loping engine idle speed is evident, do not attempt to compensate for this idle condition by disconnecting the crank case ventilation system and making carburetor adjushncnts. The removal of the system from the engine will adversely affect the fuel economy and engine ventilation with resultant shortening of engine life.

To determine whether the loping or rough idle condition is caused by a malfunctioning crankcase ‘ ventilation system, perform either of the following tests.

Regulator Valve Test

1. Install a regulator valve known to be good in the crankcase ventilation system.

2. Start engine and compare engine idle condition to the prior idle condition.

3. If the loping or rough idle condition remains when the good regulator valve is installed, the crankcase ventilation system is not at fault. Fur­ ther engine component diagnosis will have to be made to find the cause of the malfunction.

4. If the idle condition proves satisfactory, replace the regulator valve and clean hoses, fittings, etc.

Air Intake Test

This test uses the AC positive crankcase ventila­ tion tester, Fig. 34, which is operated by the engine vacuum through the oil filler opening.

1. With engine at normal operating temperature, remove oil filler cap and dipstick.

2. Connect one end of the hose to the tester body and connect the other end of the hose to the tester adapter.

3. Use the dipstick hole plug to plug the open­ ing in the dipstick tube.

4. Insert the tester adapter in the filler cap open­ ing and tum the selector knob to No. 2 (Fig. 34).

5. If the vehicle has a system with the tube from the air cleaner going into the oil filler cap, dis­ connect the tube at the filler cap and plug the tube.

6. Start engine and let it idle.

7. With plugs secure and tube free of kinks, hold tester body upright and note color in the tester windows. Following lists the various colors and probable cause or related condition of the system.

Green: System operating properly.

Green & Yellow

1. Regulator valve or system partially plugged.

2. Slight kink in tester hose.

3. Slight engine blow-by.

2. Plugs from kit o; engine vacuum lines are not properly sealed.

3. Tester knob improperly set.

Yellow

1. Regulator valve or system fully plugged.

2. Tester hose kinked or blocked.

3. Blow-by at maximum capacity of regulator valve.

4. Plugs from kit or engine vacuum lines are not properly sealed.

5. Tester knob improperly set.

Yellow & Red

1. Regulator valve or system partially or fully plugged.

2.More engine blow-by than regulator valve canhandle.

3. Vent hose plugged or collapsed.

Red

1. Regulator valve or system fully plugged or stuck.

2. Vent hose plugged or collapsed.

3. Extreme blow-by.

Review Questions

1. At what points in an engine is lubrication necessary? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2. What is the raw material from which almost all lubricants are made? . . . . . . . . . . . . . . . . . .

3. Besides lubricating moving parts, what other important function does engine oil perform?

11. Explain how the term “multi-viscosity” applies to engine oil. . . . . . . . . . . . . . . . .