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Lynn,
Hopefully the housings and irons are not permanently
warped. I also have Teflon encapsulated o-rings. Your explanation of when the
coolant enters the rotor chamber seems to be right on. I visually check the
coolant level Saturday and could not see any loss. It has been a couple of
weeks since I pulled the engine through with the plugs out and checked the
coolant level. I did a few ground runs on Saturday and my coolant pressure was
normal. I'll remove the plugs again and check the level. Once I get the plane
back from the fiberglass shop I'll start the rebuild.
Thanks Bobby (still at the fiberglass shop)
The inner, or, compression seal is made up of three different materials,
and in olden times had a strip of steel called a seal protector along the spark
plug area. I always wondered about that strip of metal, because it was on the
outboard side of the seal.
How could it protect the seal?
It couldn't. It just took up volume and possibly made for more pressure
along that area. Over time the pressure would migrate all around and that
advantage would vanish.
Then Mazda quit installing the protector, and nothing bad happened. Then it
was never seen again.
The massive pressure between the edges of the rotor housing and the iron
forms the compression seal measured in tons. There is a limit to how much help
you could get from any kind of flex seal or "O" ring. So if you fail part of
this "O" ring you will get combustion gasses in the coolant, and if you have a
system design that can get the gasses to a recovery pot or bottle where it can
escape overboard, you might not blow the coolant out of the engine. At least not
early in the failure.
Many street rotaries have gone on for years using just a bit of
coolant each week. Eventually the coolant is replaced with plain water and the
irons begin to decompose and the engine will no longer start.
The coolant enters the working chamber during cool down. When there is
still pressure in the coolant. This requires that a tiny scratch has been left
in place between the housing and the iron, and or, more than one loose case bolt
allowing for a bit of a warp. Once you have the failed "O" ring, torque on the
case bolts is of no matter. The damage has been done.
In the racer we just dump in a bottle of Barrs-leak. Probably not good
enough in aircraft use.
In the racer I torque the case bolts over two days. I use antisieze on the
threads and under the heads. I use silicone in the center and below the head.
Even if a bolt breaks it will not loose any coolant. Use a plate held
on with stationary gear bolts, so a broken bolt head cannot back out of the
hole. I have had one bolt break since 1980. I torque to the lowest
number in the range. This comes out to be way more torque than is specified for
clean dry threads. Racing Beat says 32 pounds is max for clean dry threads for
race engines. So when you see 23-25 pounds, I use 23 with antisieze..
You could remove the rear iron and replace just the failed seal. You should
strip it down and replace all of them.
One warped iron is enough to ruin the engine, so all must be checked. The
rotor housings are like rubber and can be torsioned by a warped iron. They come
straight again when removed from the engine (usually).
This may turn out to be worth what you are paying for it.
Lynn E. Hanover
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