Rotax engine troubleshooting, problems with the Rotax 582 and 532 Rotax aircraft engines.

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Troubleshooting the Rotax 532/582 Liquid Cooled Aircraft Engines.

In previous troubleshooting reports we have studied some common problems associated with the application of the Rotax engine for light aircraft use. We have also gone over some of the problems associated with the air cooled Rotax engines.

This report will deal with problems associated with the use of the liquid cooled 532 and 582 cc Rotax engines. Areas to be covered:

Recoil Electric Starter Cooling system Gear drive Fuel system
Exhaust system Ignition system Cold Seizure Engine Top End Engine Bottom End


Several problems have been reported in the with the recoil system on the 532 Rotax engine. The most widely reported is the cracking and eventual breaking of the outer housing.

This breakage first appears as a hair line crack in a circular area about 4 inches in diameter, in the center of the housing. This crack if not repaired or the recoil housing replaced, will cause the housing to completely break away. The loose parts may then fall into the magneto, or starter cup causing damage to the engine, or engine failure. Pilots have reported being able to weld the crack, the recommended solution is the replacement of the outer housing. Part # 910 107.

Another reported problem in the recoil assembly of the 532 is the disintegration of the starting cup (part # 852 322). This part is attached to the magneto with three bolts, and is located directly behind the recoil starter.

Prior to the disintegration of this cup pilots have reported hearing an unusual noise coming from their engine, then complete loss of engine power. The loss of power is caused in most cases by the parts and pieces of the cup, jamming between the block halves and the magneto, locking up the crankshaft.

It is suggested the pilots check this area on a regular basis, and at the first sign of cracks or deteriorating replace the cup.

CAUTION: When ordering parts, specifically request GENUINE ROTAX PARTS, infield inspection has shown that some supply houses are providing inferior parts, or parts that are not exactly the same size or strength as that of genuine supplied by Rotax.

Electric start

Several electric starters are available for the Rotax 532/582 engine. The only one that I recommend is Rotax supplied starter.

The starter should be used with a minimum 20 amp hour battery. The battery leads should be no more than 5 feet in length. and a separate ground cable must be run to the engine, to ensure proper ground. Several owners have reported burning up their engine wiring system when they failed to follow instructions and properly ground the engine. This is caused by the single small ground wire that is grounded to the coil mounting bolts, melting in the wiring harness, fusing wires together when the engine is cranked. This wire is not large enough to carry the kind of current necessary.

When using an electric start on a Rotax aircraft engine TWO grounds are required, one going from the engine to the airframe and another going from the engine to the negative side of the battery. These ground cables should be about the same diameter as that used on a GOOD set of booster cables, that you would use to jump start your car. (In many cases that is what pilots have used).

Other pilots have reported failure of the starter solenoid supplied with the Rotax starter. It would appear that this failure is caused by improper mounting of the solenoid. The solenoid should be mounted in free air away from vibrations, and as close to the engine as possible.

I don't even recommend using the solenoid that is USUALLY supplied with the starter from Rotax. Instead drop into your local Canadian Tire store or a good automotive supply center and get a solenoid for a Ford car, or truck. It can usually be found on the fender. I have never had one of these fail and it can be purchased locally.

Another reported problem with the starter is the failure of the studs used to secure the starter to the ring gear housing. If your starter is mounted in any position other than the 6 o'clock position failure of the stud will result in the two big washers found on the end of the stud to fall into the magneto. The washers are then picked up by the magnets with catastrophic results. Usually destroying the crankcases and ignition system.

To help prevent this it is suggested that the starter only be mounted in the six o'clock position. If the studs break in this position the washers would fall harmlessly to the ground. However I also suggest that you run a bead of silicone from one end of each stud to the other end, including over the casing. This way if the stud fails you still have the washers, and ALL of the little rubber shock absorbers that are on the studs [about $60 worth of parts].

If you have had to replace the studs, or have done other work which requires removal of the starter motor, remember that there is suppose to be a TWO millimeter gap between the starter and ring gear housing. Rotax has also updated the ring gear on the electric start the new gears are slightly thicker. The older gears were found to crack and fail around the gear teeth. Rotax also updated the spacer used to support the ring gear. The older spacers only had three support fingers while the new supports have five support fingers. Some owners have reported finding their ring gear housing breaking at the point where the stud runs through the housing. This can usually be traced to a succession of hard landings, or to the starter striking something on the airframe during acceleration.

The only other problem I have heard of is slow cranking starters, or starters that will no longer crank. This problem can be traced to the starter brushes. One brush can be replaced easily and inexpensively. The other requires the purchase of the complete plate assembly.

While not an electric start problem, the use of the proper regulator rectifier on the 582/618 can lead to the battery going flat, and the electric start not working. While the 532 can use the CHEAPER regulator rectifier the 582/618 require the use of the more expensive regulator. The reason for this is that the the 582/618 put out considerably more charging power than the old 532's. This translates to more HEAT in the regulator/rectifier. The more expensive regulator/rectifier is larger and has aluminum fins which are used to dissipate this heat.

Exhaust system

While the early two piece exhaust systems used on the Rotax engine proved to have several problems, notably cracking down the elbows, and baffles breaking loose, the new three piece exhaust is literally trouble free.

However some manufacturers in order to fit the exhaust into their cowls have welded the 90 degree elbow onto the Y pipe, or have shortened or lengthened the exhaust tuning length. This can cause failure of the muffler, loss of power, and or engine overheating and seizure.

USE the three piece exhaust as it is supplied by Rotax for best performance and reliability. When installing the exhaust make sure it rubber mounted and that the system is allowed movement. Make sure all springs and snug and that they are pulling straight, and not at an angle. After the springs have been installed properly are under the right tension, and safety wired FILL the spring with silicone. This will stop harmonic vibration and if the spring does fail the spring pieces remain in the silicone not in your prop.

On the 532/582 exhaust manifold only three bolts are used on each side to secure the manifold, while many owners have installed studs, cut down bolts etc. to fill the fourth hole it is not necessary.

If you are installing an exhaust gas temperature gauge into the Y pipe the probes must be 100 mm from the face of the piston, and in the center of the pipe. You should be using a gauge and probe for each cylinder if you intend to monitor your engine correctly.

The latest Y pipes coming from Rotax have fittings already machined into the manifold for proper placement of the probe.

"See gauging your engine"

Cooling System

Probably the most problematic part of a Rotax 532/582 engine installation is the liquid cooling system. Why? Because of the varied application of the engine. Some engines run in cowls, other in open air, in some cases the radiator is found six or seven feet from the engine.

While all of these can contribute to problems with the engine, in the form of overheating, if certain things are done properly you can just about get away with anything when mounting a cooling system. One of the first things is to have a system that allows a flow rate of fourteen gallons per minute. This simply means that if water were poured from a container into one end of the rad - fourteen gallons of fluid should go through the rad in a minute.

The next is to have someway of adjusting the AIR FLOW going through the radiator. This can be in the form of a set of louvers, or just a mechanism that adjusts the rad up and down in the airflow, The purpose of this is to maintain a constant temperature in the cooling system -especially during the change of seasons. The temperatures you are looking for are 140 degrees Fahrenheit to 180 degrees, with 160 degrees being the preferred temperature.

Many aircraft I have seen in the field exceed the 180 degree F temperature, This is not the fault of the engine it is the fault of the designer.

Other things you should remember are :

  1. Use a water temperature gauge that uses a probe that comes off the top of the cylinder head, there is a threaded hole for the probe for this purpose. I have seen some manufacturers use car water temperature gauges and have the probe come off a "T" in the line. The difference between the two locations and types of probes can be in excess of 50 degrees difference.

  2. When mixing your anti-freeze to water solution use only DISTILLED WATER! Some owners have used well water, water from a tap with a water softener, etc. The block and cylinder head used by Rotax are ALUMINUM, as soon as any other metal comes in contact with it the aluminum will start to corrode. In two cases where owners have sent me engines with overheating problems, I have had to throw the cylinder heads away because there was so much corrosion in them that the water would not flow through!

  3. Install a ROTAX thermostat. A thermostat brings the engine up to operating temperature quicker, and helps maintain it during long taxiing or long slow approaches. In my mind a thermostat should be something that every 582 should have.

It is also an item that should be visually checked every four or five months. Over the years I have seen about a dozen of them that have failed at solder joints, or have stopped working.

Cold Seizure

This is probably the most reported problem that occurs on a 532/582 Rotax liquid cooled engine. In many cases the pilot doesn't even know that he has had a cold seizure! So what is it and how does it happen? Remember this is a liquid cooled engine (cold seizures also occur on air cooled engines and for the same reason). Here is an example of a situation in which a cold seizure could occur.

A pilot flying on skis is sitting at the end of a runway, impatiently waiting for traffic to land and clear off the runway. During this time his engines has been idling. The runway is finally clear and he applies full power and takes off , about two thirds of the way down the runway and about 500 feet in the air the engine suddenly quits. The pilot is forced to make an emergency landing. Once down on the ground the engine starts and runs again.

At this point the pilot will usually do one of two things, try to find out why the engine quite - or start the engine and try another take off.

What has happened is that the engine coolant has been cooling in the rad, in winter in cold temperatures, this can mean that the temperature is down below 100 degrees F. The engine on the other hand is under load and is creating heat, the pistons are expanding. As the cold liquid enters the area around the cylinders, the cylinder shrink and this causes a cold seizure.

The problem is that cold seizures in most cases seizure only a part of the ring. This allows enough compression for the engine to continue to run. One of the first things pilots will notice after a cold seizure is that they generally cannot achieve full rpm on run up and climb out. In one case over a 50 hour period a pilot repitched his prop 4 times to a finer pitch, and dejetted his carbs down to 148 main jets from 165's before calling for help.

The use of adjustable radiators, thermostats, proper flow rates , the use of EGT gauges, and water temperature gauges, and proper pilot take off and landing procedures all help in eliminating Cold Seizures.

Fuel system

The fuel system supplied by Rotax is one of the most trouble free in the industry, when installed correctly! The majority of the problems reported are related to either improper installation or modification. There are several components in the fuel system. Lets' quickly go through some problem areas.

The Rotax fuel pump should be mounted ABOVE the vacuum hole. The pump should be no more than 12 to 18 inches away from the vacuum source The pump should be mounted flat, that is with the vacuuming inlet facing down and the top side of the pump facing the sky. The pump should be rubber mounted, in some kind of an airflow, and away from heat.

All lines should be securely clamped, and the line operating the pump should be of a thicker wall thickness so that the sides do not collapse . All lines should be inspected regularly and replaced yearly! Especially if the engine is left stores outdoors.

If an electric pump is to be installed run the pump in a parallel configuration with the fuel pickup prior to the vacuum pump and inserted back into the system, after the pump. Make sure that the electric pump you select does not put out more pressure than is recommended or you could cause your carbs to fail.

Always use a fuel filter or gascolator and mount it to the lowest point in the system. Most of the fuel filters supplied in the industry for our use should be replaced every 75 hours of operation . Other items that should be inspected and replaced at the first sign of wear, or deterioration are the oil filter, carb intake rubbers, and the carb needles and clip holders. Wear of failure of the carb intake rubbers, and needles and or clip holders is an area of repeated failures.

Another reported problem is the failure of the primer valve used to start the engine with. When it fails it creates a problem especially for aircraft with wing tanks, by allowing fuel to flow through the primer into the carb. This will flood the engine with fuel and eventually cause engine failure.

Ignition system

The only reported problems to date with the ignition system on the 582 Rotax have been with ignition coil failure. This is the external coil mounted on the carb side of the engine by the water pump outlet. Failure is detected when a loss of rpm is noticed and or an ignition check is done on the system during preflight. The only solution is to replace the coil with a new one.

The 532 Rotax has a history of ignition problems. The ignition coils have been reported to fail, and my recommendation is replacement at 150 hours, or at the first sign of problems. Another thing that plays havoc with the 532 ignition is when the magneto crankshaft seal fails. Failure of this seal allows oil to come in contact with the points and condensers. This in turn can cause a poor condenser ground which will cause erratic engine performance. Oil on the points will usually result in hard starting and loss of rpm. Another problem with the points ignition system is that the point arms WEAR DOWN and this will CHANGE the ignition timing. This can result in an engine failure due to a hole in the top of the piston. The 532 engine should have its ignition timing checked every 50 hours or twice a year.

Some pilots are using resistor plugs to suppress engine noise when then are using radios. On the 532 you can use EITHER a resistor plug OR a resistor cap but you CANNOT USE BOTH. The 532 ignition is not strong enough to run both a resistor cap and a resistor plug.

Some owners have reported the ignition missing in mid range when they have recently installed new coils or reconnected the ignition suppressor box.. When connecting the coil leads on one coil the ground wire will go to the #1 side of the coil, with the points wire going to the 15 side. ON THE OTHER COIL the 15 is the ground and the #1 wire goes to the points. On 532, when connecting the ignition suppressor box the blue/red goes to the black wire and the red goes to the blue/black.

When hooking a tachometer up to a 532 hook the tack to the generating coil wires. DO NOT connect them to the ignition wires.

While not part of the ignition system problems have been reported with the tachometer circuit on the 582. For some reason the circuit seems to destroy tachometers, some in as little as a few minutes while others may last a year or so. My only suggestion is to buy a tachometer from a company that has more than a years warranty or that will stand behind their products. Aircraft Spruce and Skysports are two companies that I recommend for this reason..

Engine Top End

Several problems have been reported by pilots with the top end of the 532/582 Rotax engine. The top end consists of engine parts above the crankcase. On the 532 failure of the wrist pin bearing is one of the most reported. Rotax updated the 582 with a new style of piston and bearing. The new piston has a hole on the intake side of the piston which allows more lubrication into the wrist pin bearing.

The new wrist pin bearing also has 31 bearings and no cage, this doubles the bearing area. This update can be done to a 532 . To do it you will require an old 582 piston, use it as a template for drilling the hole in the side of the piston and then update to the new wrist pin bearing.

The next most frequent problem is cold seizure which we have already dealt with. Rotax has also update the water pump impeller on both the 532 and 582. The new impellers now have a 6 mm hole in them, and are made of a more durable heat resistant material. Another update has been to the 582 cylinder head. There are now two vents one on either end of the cylinder head. When connected back into the rad system these vents prevent air from being trapped in the front cylinder during climb out, which prevents engine seizure.

The 532 can be update to this system easily - but it does require the removal of the cylinder head and the drilling and tapping of the head to allow for placement of the vent.

Thermostats present another problem-while it is recommended that the 532 and 582 be run using thermostats they have been reported to fail, generally a the solder joints. It is recommended that the thermostat be inspected every 6 months or 50 hours.

Once again I cannot over emphasize when filling the rad system use only DISTILLED WATER, any other water will lead to corrosion starting in your engine especially in the cylinder head.

Gear Drive

When dealing with Rotax gear drives there are really three different drives. The first is called the "B". The B drive was found on all the old 532's. This drive used an adapter plate between the gear drive and engine. The adapter plate used four allen bolts to secure it to the engine. The gear drive then bolted on to the adapter plates using 4 of the 6 studs used to secure and fasten the two gear box halves together.

The most reported problem on the 532 was the loosening off of the 4 allen bolts securing the adapter plate to the crankcase. This can result in a broken crankcase, loss of oil in the drive resulting in seizure of the drive, or broken gear(s).

Another reported problem with older model engines is with loss of gear oil from the gear box. this is caused by pressure building up in the gear box and a siphoning action occurring through the vent cap. The solution is to update to the newer style of Rotax gear box vent cap. It is a domed style cap that prevents this from occurring. Pilots have reported hard starting of their engines, or the engine not coming off an idle when it does start. This occurs when the springs inside the gear box weaken. I recommend replacement of the springs at 300 hours.

Also at 300 hours or at the first sign of wear I recommend the replacement of the two locking rigs that retain the output shaft gear in place. When replacing the two half moon rings check to make sure that the shaft area where they ride is still in good shape, and not worn.

At 300 hours I recommend that the bearings in the the be checked for wear and replaced if found to be worn or damaged. All seals and gaskets should be replaced as well.

Gear failure is especially the main gear is another area of concern. Failure generally shows up as chipped teeth on the gear which if not replaced will lead to the gear shattering. This is more apt to occur on craft using large diameter propellers or propellers hat are improperly balanced.

On late model 532 and all of the 582's the gear box bolts directly to the crankcase, using two bolts inside the gear case and six bolts on the outside. Thus the cases, and gaskets are different than those found on the 532. The gears, bearings, spring washers and shaft etc. are the same. So if you have a 582 all of the above reported problems other then the loosening of the allen screws are of concern.

The "C" and "E" Drives

The basic difference between the "C" and E" drives is that the "E" drive has a built in electric starter. The most reported problems with both drives is the failure of the seal which is located in the rear housing where the rubber donut is found. Failure of this seal can generally be noticed when gear oil starts to show up in the two large hole found on the side of the gear box or when gear oil is found dripping from the back of the gear box. In one case that I know of the seal failed and gear oil exiting the drive landed on the exhaust system filling the cabin full of smoke. It is a good idea to check this area on every preflight and at the first signs of leakage have the seal replaced. When replacing the seal check to make sure that the shaft does not have a ride on it where the seal rides. If it does try using a very fine emery paper to remove the ridge, or reverse the direction of the seal so that it has a smooth surface to ride on.

Failure of the rubber donut is another problem. Rotax has updated the donut several times. When ordering a new donut make sure to order it for the proper engine, different engines use different donuts. The use of the wrong donut can greatly effect engine performance.

For parts description click here ROTAX ENGINE PARTS

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