Engines - Wright-Maint

Instructions for the installation, inspection and maintenance of the Wright Whirlwind Aviation Engine

Models J-4B J-5A J-5C

Wright Aeronautical Corporation - Paterson, NJ

January, 1927

WRIGHT WHIRLWIND ENGINES

CHAPTER V.

Inspection Routine

In order to obtain maximum reliability and service from Whirlwind engines a regular schedule of inspections and overhauls should be maintained. Serious failures very often arise from minor causes which a few minutes inspection could have averted. The following schedule is suggested.

Starting Inspection: See page 23.

Daily Inspection: Every flying day the following inspection should be made. Check all- cylinders, one at a time in firing order (1, 3, 5, 7, 9, 2, 4, 6, 8), as follows: Models J-4A and J-4B

1. Does clearance between rocker roller and valve stem, on compression stroke, seem normal?

2. Are rockers free on shafts and lock wires secure ?

3. Are rocker rollers free and lock wires secure ?

4. Are valves free in guides?

5. Are valve springs and valve spring retainers intact ?

6. Are rocker support lock nuts tight and are rocker rollers central on valve stems?

7. Are spark plugs tight?

8. Grease rocker shaft with Alemite gun using automobile transmission oil.

9. Oil rocker rollers with engine oil.

10. Are ignition terminals secure to wires and plugs and is insulation on wires intact?

11. Is compression normal?

After all cylinders have been checked proceed as follows :

12. Are carburetor and carburetor manifold tight at securing flanges?

13. Are fuel tanks filled ?

14. Is oil tank filled?

15. Are magneto ground wires secure?

16. Are throttle, mixture and magneto controls free throughout their range?

17. What is full throttle R.P.M.?

18. Is engine operation good on either magneto?

19. What are oil pressure and temperature? Compare with values given on page 25.

20. What is gasoline pressure? (Should be 2-4 lb per sq. in.)

Model J-5

The daily inspection of the Model J-5 engine should include items 7, 8 and 10 to 20 inclusive.

Twenty Hours:

After every twenty hours of flight the valve gear should be disassembled and inspected as follows:

Models J-4A and J-4B

1. Remove push rods and examine balls and ball sockets for wear.

2. Grease sockets in rockers.

3. Thrust lower ball ends of push rods in can of heavy grease and replace the rods in their proper sockets.

4. Make complete inspection as outlined for each flying day.

Model J-5

1. Remove the rocker box covers and make a check of the amount of motion of the various parts. If the tappet clearance seems normal it should not be disturbed. If any part seems to have too much motion, or if the tappet clearance is excessive, the rocker arm and push rod should be removed and the cause determined. Check the offending part against the maximum allowable clearance as indicated in the charts on pages 136 to 144 and replace if this is exceeded or if in the opinion of the operator it seems advisable.

After the valve gear has been inspected, repaired and reassembled the following items should be checked (all "J" series models except as noted) :

1. On J-4 series engines check clearance between rocker rollers and valve sterns with feeler and reset to .010. Be sure adjusting ball and lock nuts are tight.

2. Are spark plug points clean and are gaps set at proper clearance (.020" to .025" for A. C. Plugs ; .015" for B. G. Plugs).

3. Are nuts on inlet pipe upper flanges tight?

4. Are inlet pipe packing nuts tight?

5. Are cylinder hold down nuts tight?

6. Are fuel strainers clean ?

7. Are fuel lines and connections secure and free from leaks?

8. Is lock on gasoline pump pressure adjusting screw secure?

9. Are oil strainers clean ?

10. Drain the old oil from the tanks and lines and flush with kerosene until perfectly clean. (Do not use kerosene inside the engine.) Replace the lines and put two gallons of clean oil in the tank. Run the engine for twenty minutes and then drain out all the oil again. Replace the lines and fill the tank with clean oil, (Great care should he taken to see that all the oil lines are replaced properly and there are no air leaksl Small air leaks are apt to interfere seriously with the proper functioning of the lubricating system.

11. Oil tanks should be drained and filled with fresh oil.

12. See that hand turning gear is well lubricated.

13. Are engine mounting bolts tight?

14. Does each magneto get full advance when operated from cockpit?

15. Are magneto breaker points clean and gaps set at .012"?

16. Are magneto couplings in good condition?

17. Put four drops of medium machine oil in rear magneto oil holes. Fill front holes.

18. Are propeller hub lock nuts and propeller hub bolts tight ?

19. Check the clearance between the rear of the rocker boxes and the cylinder heads and make sure it is .031" (Engine cold ). While this dimension should not vary it is extremely important and should be checked carefully. Incorrect clearance is very apt to result in failure of the rocker box studs.

It is advisable to run the engine at part throttle for at least 1/4 or 1/2 hour twice a week in order to keep interior parts flushed with oil. This will prevent the vapor due to condensation in the crankcase from rusting steel parts.

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Complete Overhaul

It is suggested that the compression, as noted in Item 11 of the daily inspection, be checked very carefully on each cylinder. As soon as one is found to be low it should be removed, the valves tested for leakage and the piston rings checked for tension. The valves should be ground and the piston rings replaced when necessary. ( See page 50.) In this manner the engine can be kept up to power and speed. It is sometimes very difficult to distinguish between a valve which is leaking and one which is being held open by a bit of dirt or carbon on the seat. The only way to check this out is to run the engine for several minutes and then try the compression again.

Experience with "Whirlwind" engines in service has indicated that the length of the period between overhauls is limited by the tendency of the lubricating system to fill up with sludge. This is composed of gums formed in burning the lubricating oil, carbon, lint and substances taken into the engine through the carburetor or breathers. After 200 hours of service the accumulation is likely to become severe enough to plug up one of the passages resulting in the seizure of the bearing whose oil supply is cut off. It is therefore recommended that "Whirlwind" engines be given a complete overhaul after every 200 hours of service.

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Wright Aeronautical Corporation

Service Instruction No. 35.

Subject: Setting Valve Tappet Clearances.

Models: All "Whirlwind" Engines.

Reference: Page 68 Paragraph 11 in Instruction Book for Wright 'Whirlwind" Engines.

In setting the tappet clearance it is essential that the piston of the cylinder in question be at top center on the firing stroke. Unless this is done, it is quite possible for one of the tappets to be riding unnoticed on the rising part of a cam, causing an error in the tappet setting.

To avoid the possibility of making this error proceed as follows: Turn the crankshaft until the valves of the No. 1 cylinder indicate that the piston is on top center at the beginning of the suction stroke. At this point both the valves will be open and the keyway in the shaft will be facing the No. 1 cylinder. If the propeller is mounted on the shaft one of the blades will be in the line of the keyway. Then turn the shaft through one complete revolution and set the clearances on the No. 1 cylinder in the manner prescribed on page 68. Having done this turn the crankshaft in the direction of rotation until the keyway or propeller blade is facing the No. 3 cylinder and set the clearances. Repeat on the rest of the cylinders, taking them in the firing order (1, 3, 5, 7, 9, 2, 4, 6, 8).

5-1-27

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Service Instruction No. 36

Subject: Valve Operating Mechanism Adjustments

Models: "Whirlwind" J-5 Series

References: Instruction Book for "Whirlwind" Engines pages 62 and 63, page 34 paragraph 19.

Reports from the field seem to indicate that the operation and maintenance of the valve gear on the J-5 Series "Whirlwind" engines is not thoroughly understood. Furthermore, since a number of engines of this series have been in service for a considerable time, additional points of interest relative to upkeep have been brought out. Consequently it has been found advisable to issue this service instruction to bring up to date information for maintenance found in the manual.

The following routine is suggested for checking the valve gear. This should be done on one cylinder at a time following the method outlined in Service Instruction No. 35.

1. After the engine has been in service for 20 hours loosen the push rod housing clamping screw And back off on the adjusting nut until the push rod housing is free. With a set of thickness gages check the clearance under rear end of the rocker box. To this value add .005" and tighten up on the adjusting nut until the increased clearance is obtained. Then tighten up on the clamping screw. It is essential that this be done when both the valves are closed to prevent errors caused by the forces set up when the valve is opening or closing.

2. Check the valve tappet clearances in the manner prescribed in Service Instruction No. 35. Just before checking the clearance, the push rod end of each rocker arm should be tapped sharply with a hammer handle to make sure the roller is riding on the cam. The cam followers are fitted with very little clearance and are sometimes too tight to be moved easily with the fingers, necessitating this operation. It has been noted that many operators make curved feelers .040" thick for setting the tappet clearance. This type gage is very handy for checking the clearance but for resetting it is recommended that the method described on page 68 be followed.

3. Every twenty hours the cotter pins should be removed and the rocker arm pin nuts (Part No. 19415) checked for tightness. This is very important'as any looseness on the part of this nut permits the rocker arm pin, sleeve and thrust washers to turn and is apt to cause serious wear in these parts.

4. It is most important to use the correct type of grease in the rocker arms of the "Whirlwind" as many types will become hard and carbonize at the temperature to which they are subjected. Grease containing soap and graphite are most objectionable in this respect and should never be used. Automobile transmission oil has been found satisfactory for rocker arms but care should be exercised not to over-grease these parts as the lubricant may get on to the hot valve stems and stick the valves by the carbon formation. When Uniflow lubricators are used for long endurance flights, vasoline is found satisfactory as it flows at the proper rate to give lubrication for a number of hours.

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WRIGHT WHIRLWIND ENGINES

11—Tappet Clearance

On the J-4A and J-4B models the tappet clearance is set at .010" for both intake and exhaust. The adjustment is made on the upper end of the push rods where the ball end shank screws into the rod proper. Keep the rod from rotating by means of a wrench on the hex provided for that purpose, loosen the lock nut, and then screw the ball end in or out until the .010" feeler (WA-81) becomes a snug fit between the roller and the valve plug. Bring the lock nut up tight against the rod and then check the clearance to make sure the ball end has not rotated while being locked.

The adjustment on the Model J-5 is quite different, the clearance for both tappets being .040. Loosen the clamping screw on the push rod end of the rocker arm and with a large screw driver turn down on the adjusting screw until the rocker roller touches the valve plug. Then back off on the adjusting screw until the arrow on top has passed eight divisions of the scale on the rocker arm (each division is equivalent to .005" clearance on the valve stem). Lock in place by tightening the clamping screw.

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Lubrication Instructions

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should be ground and that end placed in the cap so the uniform contact with the ball will not be destroyed.

If for any reason it becomes necessary to readjust the regulating valve, make the adjustment only when the oil is warm. If on starting the engine the oil pressure gauge registers no pressure, stop the engine immediately and look for:

1. No oil in reservoir.
2. Broken or clogged intake oil line.
3. Broken or clogged pressure gauge line.
4. Loss of pump prime.
5. (In winter) Oil congealed in oil intake line.

Draining Oil Tank

Periodic draining and cleaning of the oil tank is one of the most important factors in reducing wear and maintaining engine efficiency.

Oil becomes contaminated with continued service. Its lubricating value is not actually destroyed but it does become thinned with the fuel absorbed by the oil film on the cylinder walls, which is scraped back by the piston-rings and mixed with the crankcase oil. This dilution is greatly increased when the carburetor is set for an over-rich mixture or by excessive priming. The crankcase oil becomes further contaminated with carbon flaking off the inner side of the piston heads, particles of worn metal and dust drawn in through the carburetor during ground running.

When to Drain

After every twenty hours of flying the engine oil should be entirely drained off. The best time to drain the oil is just after a flight when the oil is heated. The oil is more fluid at the higher temperatures, and being thoroughly agitated, it will carry off most of the sediment.

Clean Tank

After draining remove the oil lines and flush both the tank and lines with kerosene. Replace the oil lines, pour two gallons of fresh oil in the tank and run the engine for twenty minutes. Again drain the tank and refill with fresh oil.

Oil Screen

Wright Whirlwind engines are equipped with three oil screens or strainers. The main oil strainer through which the oil from the tank passes before entering the hollow crankshaft, the finger strainer in the oil sump suction line and the scavenging line finger strainer in the bottom right side of the rear section. All of these strainers are readily accessible for cleaning and inspection.

When To Clean

After each twenty hours of flying remove and wash all of them thoroughly with gasoline or kerosene kerosene and dry with compressed air or a lintless cloth.

Where Located

The main oil strainer and one of the scavenger pump screens are located in the rear crankcase section. (See Figure 4). Both can be removed by turning the brass end plate to the left (anti-clockwise).

The other scavenger pump screen will be found at the lower end of the oil line leading from the intake manifold to the pump (See Figure 5). It can be removed by detaching the oil line.

Oil Pumping and Carbon Deposits

"Oil Pumping", in the common use of the term, refers to an accumulation of oil in the combustion chambers rather than to the quantity which actually passes the pistons. With...

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5. Be sure that the carburetor is not feeding too rich a mixture. If there is not enough air to consume all the fuel, there certainly will not be enough to consume any excess oil which passes into the combustion chamber. Incomplete combustion means carbon.

6. "Missing" promotes oil pumping and carbon formation because the oil normally passing into the combustion chamber is not burned. Keep the ignition system in good condition.

7. Compression losses affect the efficiency of the engine and the complete combustion of oil and fuel. Keep the valves properly ground in and the tappets properly adjusted.

Sludge

Sludge, though not particularly prevalent in air-craft engine operation, may become troublesome under short flights or extremely low temperature conditions to the extent of clogging some of the smaller oil passages or the oil screen.

Sludge is an emulsion of oil, water and impurities which accumulate in an engine run too cold. Water vapor constitutes a large percentage of the exhaust gas in normal combustion. As long as the cylinder wall temperature is above 120°F. this vapor passes out the exhaust port and does no harm, but with a comparatively cold cylinder wall this vapor condenses on the oil film and some of this moisture is scraped into the crankcase by the piston-rings on each downward stroke.

Agitation of the water, oil and impurities by the circulating pumps whips these substances into a permanent mixture or emulsion. When this emulsion is forced into the whirling crankshaft centrifugal force separates the sediment from the mixture and deposits it on the outer walls of the drilled passage. If this deposit becomes excessive, it may clog the lead to the master rod bearing or the leads to the cam disc bearing and the magneto drive shaft, and cause serious damage.

Sediment can be minimized by following the draining instructions on Page 14 of this book for without impurities emulsion and sludge are impossible.

Rust - Corrosion

Occasionally some of the polished parts of engines, such as the piston-pins and valve stems, are found to be rusted or corroded. This trouble is due, first, to the presence of water in the crankcase and, second, to the fact that badly diluted oil does not protect the working parts from the rusting action of the moisture. If this moisture is made acid, as it can be through the use of fuels containing excessive amounts of sulphur, the surfaces may become corroded very rapidly. Any sulphur which is contained in the fuel burns in the cylinders and forms (Wikipedia) sulphur trioxide (SO₃). If there is leakage past the pistons and rings, part of this sulphur trioxide will find its way into the crankcase along with a considerable quantity of water vapor,—one of the products of combustion. When the engine is cold, this water vapor will condense into liquid form and unite with the sulphur trioxide to form (Wikipedia) sulphuric acid (H₂SO₄). If the crankcase oil is badly diluted, it will drain off of the parts, leaving them exposed to the action of this acidulated moisture which of course, tends to corrode them. Even if the fuel is free from sulphur compounds which would form acid, the parts may rust due to their becoming coated with moisture.

Rusting and corrosion troubles play be avoided by observing the following precautions, as there can be no rusting or corrosive action if the parts are protected by oil:

1. Minimize dilution by using the mixture control to keep the fuel consumption at its most economical value.

2. Keep the engine in such mechanical condition that the burning gases will not readily pass the pistons and rings.

3. Use the correct oil and keep it in good condition so that the pistons will be sealed against leakage.

4. Follow the draining suggestion given in this book.

Valve Gear Lubrication

The valve rocker arm assembly is lubricated through high pressure fitting mounted on the end of the rocker arm shaft. By means of the grease gun, supplied with each engine, apply Gargoyle Mobiloil "C", or high grade gear oil of similar body, every flying day, and oil the rocker rollers with a few drops of engine oil at the same time.

Magneto Lubrication

The Scintilla magnetos, which are standard equipment on Wright Whirlwind engines, should be lubricated every 20 hours of flying time with a high grade light bodied oil such as Gargoyle Mobiloil Arctic. Apply four drops to the rear oil ducts and fill the front ones.

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