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Chris,
Take a straight edge and make certain your side housings are not warped. The rotor housing and side plate need to have a tight fit. Any debris that may have gotten lodged (could be very small piece of metal) between rotor housing and side housing could cause a leak into the rotor housing. Same bit of metal might be very hard to find upon disassembly.
The fact that your bearing was destroyed may have contributed - check your side housings to make certain the rotor wasn't scrapping/pushing on the iron housings as it ran due to the failed thrust bearing. Without the bearing those rotors could have been moving laterally much more than normal and possibly contact the side housings. I don't think that would cause the coolant leak, but wouldn't hurt to check closely.
If the O ring had not seated properly (gotten pinched) it can be hard to tell upon disassembly but could have compromised your sealing - you might be able to spot the pinched area - but perhaps not.
The ONLY ways I am aware of for coolant to get into your rotor housing are:
1. A compromised "O" ring (bad ring, pinched ring or too much heat) - generally the most common cause of leakage.
2. A bad "O" ring lan in the iron side housing - this can be hard to find, because the vertical wall may look fine, but you might have a crack at the base of the vertical wall of the outside part of the groove in the side housing. Take a dentist pick and pull the tip along the inside of the "O" ring grove - particularly on the outside part. If you get any catches - check that area very carefully.
3. A hole in the side housing or rotor housing through into the coolant galleys - but that should be readily apparent
4. Very unlikely but made certain your spark plug hole through the rotor housing doesn't have a leak to the coolant galleys. Plug up one end (inside the rotor house - say with your finger) of the spark plug hole and then force compressed air into the other end of the spark plug hole - it should cause air to blow past your finger - if not you have a hole into the coolant galley.
5. With the older aluminum rotor housings - there was a belief that if they got too hot, the compressive forces of the tension bolts could cause the housing to "shrink" (compress) a bit in width. There was a specification about minimum width permitted the rotor housings.
Very early on I overheated my 86 N/A and got a coolant leak. When I check the housing, it was at the very minimum limit - now I've always sort of doubted this "shrinking" took place, but apparently Mazda did not. So you might check the housings width before putting it back together just on the outside chance.
All I can think of
Ed
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----- Original Message ----- From: "Christopher Barber" <CBarber@TexasAttorney.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, March 09, 2008 10:14 PM
Subject: [FlyRotary] Re: Coolant leak - the teardown
So guys, what do y'all think. What do you think is causing the coolant in the rotor housings. I really want to figure this out before I put the dang thing back together. Your help is appreciated. TIA.
All the best,
Chris
----- Original Message ----- From: "David Staten" <Dastaten@earthlink.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, March 09, 2008 8:29 PM
Subject: [FlyRotary] Coolant leak - the teardown
Well.. today we tore the engine apart.. the short and sweet of it is there is no obvious source of a coolant leak.
Took the engine apart without too much trouble..
As we pulled off all the housings we checked the rotor faces, the grooves, the seals and the intake ports for any sign of a leak or blowout. None was forthcoming. I had expected to see a blown out coolant o-ring groove, but all were intact. Felt the intake ports, no sign of a problem there either. I had only ported the center iron, so the other two end irons were stock. So as it stands, we have an engine that is giving us no obvious reason for a coolant leak. The bolts werent loose at all.. they were so snug from tape and silicone it took a hammer and vise grips to extract them once they were untightened.. So thats the semi good news..... nothing obvious.
Now the bad news..
When we took the engine apart, I was concerned about how the rebuild itself went.. and how things held up to our first attempt at building the engine. I examined things as we took them apart and paid particular attention to the front end.
I was even showing Chris how the front bearings can be a problem if you loosen the front bolt and cause a bearing to get pinched.. well the front bearing on the outside of the thrust plate looked fine. Took off the thrust plate and discovered that the other bearing had destroyed itself. At this point, Chis chimed in that there was metal bits in the oil when he drained it, and lo and behold the bits resembled the roller pins in the bearing..
The spacer had welded itself with the inner ring on the destroyed bearing, forming a spoked wheel, and the inside of the thrust plate had wear damage to it as well.
I am certain i know when this happened. During assembly, everything went as it should. end play was ok. I had installed the stock pulley on the front at the time of rebuild. After we added the PSRU I was no longer able to check end play, as it secured the engine's flywheel travel.
At some point, we purchased and I added a double pulley, and while i took care not to let things shift around, I am suspecting that this is when it happened. The lesson: don't remove the front nut if you cant check end play or put the engine vertical.
The remainder of things looked great - no missing pieces, nothing burnt, no gouges... 10 hours of use on the ground and thats what weve found.
Dave
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