In the olden days, I would be gifted rotary engines. Once found one in my driveway. Other folks would leave a note in the door about a free engine, and in several cases a whole car. My electric car was a free RX-2 4 door. Some cars got straight weight oil used in them, and they lasted quit a while. Others got multi-grade oils and they didn't do so well. The OMP (Oil Metering Pump) steals a bit of crank case oil and dribbles it into the carb (in the old days) where it mixed up prety good before going through the engine.Those rotors got a nice hard coat of carbon build up with straight weight oil, and a slimy wet looking gummy carbon build up with multi grade oil. The straight weight didn't burn well and a build up could eventually stick a seal, and make for poor running for a few minutes, and hard starting. The multigrade plastics would glue a seal at its deepest travel in the groove, never to move again. So most do not recover and need to be rebuilt, or as many have found, treated with ATF. Mazda dealers had a specific instruction for decarboning engines this way. Many died of bearing failure with most of the breakin oil still in the sump. (Nobody in Japan could imagine that a car owner would not check the oil before every use). About a cup full usually. So Mazda dealers got good at swapping engines under warrantee. Some people would just not check the oil level, and Mazda was desparete to attract and keep customers. The rebuilds were done in Chicago, and dreadful, and made up of whatever parts were left after two or three engines were torn down. So I got one of those as a gift. The big expence in those rebuilds was the Permatex used to glue the junk pieces together. Not a good move for Mazda.
For the unwashed.......the engines collect fuel and hid it in the sump, where it mixes quickly with the oil.
So for those who actually do check the oil level, it may appear that none has been used even with the OMP active, when in fact it has, and the missing oil is being replaced by the fuel. The malady is more likley when premixing oil and fuel. When the OMP dribbles oil into one or two ports in the rotor housing, little oil gets to the side seals and on to the oil scrapers to be gathered and dumped into the sump. When premixing the ramps on the oil scrapers face the wrong way to prevent oil from entering the sump, but are designed to keep oil from the sump, in the sump.
So in those cases oil levels may increase over time. This is not a giant problem. Bearing surface areas are huge for the loads involved, so oil quality is not very important. If you smell a strong odor of fuel on the dip stick, change the oil. If the oil level seems to be going up, change the oil. Use new oil scrapers and springs during rebuilds. Learn the handedness of the springs. Colored dots show front or back springs.
Lynn E. Hanover
Greg, using ATF is a "common" method of freeing up stuck Apex seals. When left sitting for long periods, people who owned older RX-7s would go out one morning and attempt to start their autos. They would hit the ignition and the engine would wiz over with no compression. A number decided that the *&@) engine was shot and practically give a way the auto and engine.
Pull a spark plug from each chamber, pour in some ATF, Marvel Mystery oil, WD-40 or your favorite light weight oil , let it sit a while (over night seemed to be the most common waiting period) and the next morning – Zooooommmmmmm!! Compression and a running engine.
So for old engine or engines with worn or stuck seals, a fluid like ATF may help compression at lower rpm and assist in starting, I doubt very seriously they would do anything for you at higher rpm. But, someone like Lynn could enlighten us all about this "urban myth".
Ed
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Greg Ward
Sent: Friday, December 19, 2008 8:54 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: engine preservation
I just read a great article on running ATF through the Rotary, supposedly to loosen up the apex seals, etc. (high detergent level). Raves on about having done this multiple times in many engines, and supposedly power increases of up to 20% +. Anybody done this? Results?
Lancair 20B N178RG in Progress
----- Original Message -----
Sent: Friday, December 19, 2008 5:35 PM
Subject: [FlyRotary] engine preservation
Lynn, thanks for the heads up on the engine. Even though it is in a heated garage with hot water heat in the floor, I pulled the plugs and put oil in each rotor cavity and rolled it over 8 revolutions and duct taped the exhaust. That should even oil the muffler bearings when I start it again. JohnD
|