Long ago at an airport not so far away, on my last few flights I suddenly began to see coolant pressure spikes when engine power was increased. Pressure would fall off when power was decreased. There was a small but measurable amount of coolant loss, but no external coolant leaks and I couldn't detect the smell of coolant in the exhaust while idling. Of course while under high power I was in the air and unable to sniff the exhaust!

   So in a foolish moment I decided to put a small bottle of coolant stop-leak into the coolant.

I flew a few more times then life got in the way, I brought the plane home for the winter and completely forgot about the cooling issue. I had poured some oil into the intake ports and rolled it over a few times in an attempt to preserve the inside of the combustion chamber.

   10 years later and as I began to work on the plane again, I pulled the plugs and found that one of the rotors had some awful looking plugs, so I took the turbo off to look in the exhaust ports. I was shocked and disappointed to see an awful corroded mess in one rotor while the other looked good. So a tear down was the next obvious step.

Go to the google photos link below to see what I found.

   So first thing was "what the **** is that blob" as I'd forgotten putting the stop-leak into the system. So that's what that **** does to your system! I won't use that again. After cleaning it off I could see the source of the leak with the o-ring still in the groove. Apparently this is not unheard of with these o-rings, so I replaced them with the stock o-rings.

   The irons looked trashed at first, but a little work with a scotch-bright pad and some WD-40 and they surprisingly looked not so bad, but measuring the wear at the plug side it was right at the max allowable. I inquired about getting them lapped at RX7 Specialties, which was very reasonable, but I ended up just buying some that he already had done as the price difference was about what it would have cost to ship mine to him. As a bonus I got a newer center iron from a turbo engine which had a few advantages for me as my original engine was not turbocharged.