The first problem that I had was while doing the engine break-in. Rans manual suggested putting a fan in front of the aircraft while doing the break-in to force air through the radiator. My engine kept trying to overheat, I did not let it. I shut it down and called Rans the next day. I explained the problem and they told me that I would need to run a water hose into the radiator scoop and let the water run through it while doing the engine break-in. It would have been nice if that had been in the manual! I did that and it worked fine. When you do this, you need to have a friend adjust the water pressure and only give it enough to keep it from over heating, you want it to get hot, that is what the break-in is for, but not overheat. This may sound weird, but I've done it and it is want you will need to do to keep it from overheating. Once you are flying the air passing through the radiator is enough to keep it cool.
The next problem to arise caused me to create The Crash Site. I had read a lot about not letting your engine overheat, but I had never read anything about letting it get to cool. On Aug. 23, 97, I had climbed to 12,000 ft msl from about 550 ft msl, I did it just to see if I could. I watched my water temp and did not let it get too hot. I idled back and came back down. The engine was running great and I was not having any problems with it. On Sept. 1, 97, I took off on a short trip. I flew over my brother-in-law's farm and descended from 1,500 ft agl to about 600 ft agl, at idle. The engine seized and I had no time to think. I tried to turn around and stalled the aircraft into a corn field. I believe that I scared the cylinders and pistons when I descended from 12,000 to 550, when I descended from 1,500 to 600 a few days later it started to do the same thing again, but this time it seized. Knowing what I know now, I can not see why it did not seize on the that first long decent.
What happened is the cylinders cooled faster than the pistons, also at idle the engine is getting less oil, on an oil injected engine, but the prop is spinning faster during a decent, rather than level flight at the same throttle setting. From this I learned two things that I had not read in the books. First, when descending keep a little throttle, do not go under 4000 rpm unless you are on finale approach and give a little throttle every couple minutes during a decent. The next thing was to put a thermostat on the engine in the the cooling system. The thermostat will help keep the engine from cooling too fast. On a Rans S12xl the water temp gauge is installed at a point just before the water enters the radiator. I also installed another one on the top of the cylinder head, there is a place for it that is plugged in the center of the head. I ordered one from CPS and they sent me the wrong one for the gauge thatg I told them I had, it did not read correctly on my VDO gauge. I chose the VDO gauge because that is want Rans sent for all the other gauges. I Called VDO and found out what the correct sender for my gauge was and then I called CPS and explained the problem to them. They said that they would change their information to show the correct sender for that gauge. I had a hard time convincing them that they were wrong, they had that (that's the one we've always sent for that gauge) attitude, but with some help from VDO, they were convinced. With both gauges I can keep a closer eye on that water temp. I never take off until the water temp at the radiator is 120 degrees F. The water temp at the head is about 130 degrees F. More on water temps later.
The next problem to come along was water in my rotary valve oil reservoir, you will notice it when you see the level go up rather than down. Look inside and you will see that the oil has turned mint green. If this happens, you will need to replace the rotary valve shaft and seals. Instruction can be found at: http://www.rotax-owner.com/index.htm. This site contains all of the Rotax Service Information Documents. If you look up SI-01-1991 it will show you how to replace the rotary valve shaft and seals. If you look up SI-1-KUL-96-R1 that will explain this problem and what causes it. What happens is that the seals cut very small grooves into the shaft. I tried replacing just the seals, but that did not help. Once I removed the shaft I could easily see the small grooves. To keep this from happening again you will have to insure that you do not have too much water pressure. I found that the radiator cap that was supplied by Rans was a 13 lb.. cap, after doing some calculations to I found out that half of that would work fine. I replaced the 13 lb. cap with a 7 lb. cap, after replacing the rotary valve shaft and seals, and have not had a problem since. The water pressure of your system will be what ever the cap is rated for. I have a picture of the old and new shaft, but cannot find it, when I do I'll put it here.
This problem is one that I think is unique to the 582 set up on a Rans
S12xl. The reason I say that is that I have found out from one other Rans
S12xl owner that he has the exact same problem. I have found that I must
do a decarb every 75 hrs. Not so much because of a lot of carbon, but
because the rings will be stuck at the 4 to 5 o'clock position with the
front of the engine being 12 o'clock. This can not be found by looking
in the exhaust ports the only way you can tell is by pulling the cylinders.
When I say a decarb I do not mean just pulling the head and cleaning the
top of the pistons, you must pull the cylinders off (be sure to mark them
as frt. and back so you can put them back in the correct position), then
take the rings off of the pistons (only do one at a time so you do not
mix up the rings), you will need to clean out the ring grooves real good.
The CPS catalog explains how to do a decarb. When you put the cylinders
back on you can use the exhaust manifold to align the cylinder before tightening
them. Next time I decarb, I will try to get a few photos and put them here.
One more thing that I need to bring up is that during cooler weather it is normally nessecary to block off part of the radiator to get the engine to run at the required temp. You can see in the picture of the radiator,near the top of the page, that I have a red shop towel showing in my radiator scoop. The colder it gets the more shop towels I place in the scoop. You may find other ways to do this, but this is simple and works good for me. I actually have to lower the radiator about an inch and a half during the summer when it gets real hot. I made small extension plates for each side to allow this. If your water temp is running to cool block a small area of the radiator, block a little more if needed until the water temp is around 160 in normal flight.
That is all for now, as I learn more I will try to update this site. Remember, I have only given you the information that I have learned and found to work for me. Others may have different ideas and may disagree with what I have done. I am always learning more about my engine setup and want to hear others ideas that have been done. I created this site because of the lack there of, of this type of information. I wish that I had read information like this before these things happened to me. Any questions or comments are welcomed, just send me e-mail.
Here is the story about my engine seizure which happened on 10/15/00:
There I was at 3000'msl, beautiful foliage, beautiful Lake Cumberland, perfect weather except for the 10 mph head wind, when I thought I heard my RPMs drop just slightly. I had been at about 5800 rpm and now it is about 5700. Maybe I slightly bumped the throttle, a slight touch and it's at 5800 again. A few minutes later the same thing. Ok maybe the screw in the friction block has loosened up a tad, back to 5800 and maybe I'll just keep my hand on it for a while. A check of all the gages, everything is right where it should be, I had just flown over Russell Co. airport about 13 miles back and was now about 8 miles due south of Columbia-Adair Co. airport, everything seem fine and I had just about determined that it was that friction block when the RPMs decided that they would go ahead and drop a little more, while I was holding the throttle, now this isn't good. I had a buddies son (Phillip) in the passengers seat and I had turned the intercom off to cut down on the noise, so I reached up and flipped it back on and told Phillip that we had a problem and we were going to have to land, he asked what kind of problem and I told him engine problems, just hold on good. While this was happening I had spotted a field that looked like it would do the trick, oh and did I mention that the engine had now quit. Well I knew I was fairly close to Columbia-Adair Co. airport but my GPS was on another screen so I started flicking through the screens for the right one. At about the same time I was shooting the primer to it and trying the start it again. I tried about 6 times no luck. Did not need to worry about where the airport was any more because it was not in site and I was parallel with the field I had spotted and at about the right downwind height. A quick look around for another possible site, nope! OK here we go! Nice field just bailed, with bails spotting the field. They don't appear to be a problem, there is a row of power lines along the right side of the field, start turning base and ease on around to FINAL approach, at least for this flight. OK I'm a little too high, S-turns to loose some altitude because the field does not appear real long and a tree line at the far end, turn to the left, look at all those trees, another turn to the right, would you look at that, another row of power line on this end of the field but I'm high enough. OK lets get her straight, past the lines, now down, get on the ground, were movin on, vise grip on the brake handle, we're headed to the left rear corner of the field but were still movin on, full right rudder, squeeze that brake handle, baby. We're starting to skid around to the right. Skiddd, skipppp, skiddd, skipppp. Would you look at all those trees, just about 15 feet off the end of my left wing tip, hey we stopped.
--------- I'm ok, Phillip is ok and My Blue Angel is ok, well except for some engine work. We finally got home about 10PM.
More later ...... Got to go to bed.
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