Hi All, As you know I'm replacing my Hirth engine with Jabiru 2200. This weekend just gone I pulled the wings off and bought the aircraft home. I've removed and weighed everything from the firewall forward and the old retractable suspension. Now I'm just waiting for the new parts.
I'm posting this so others may learn from my ill fortune. The reason why my Hirth is un-usable. ------------------------------------------------------- I can now discuss the cause of the problem as all issues have been resolved (I'm the one left holding the bag) My Hirth had only 10 hours and once it got hot was down on HP and would run rough. After 6 weeks trying to find an external problem (fuel, electrical, vacuum, etc) I pulled the engine and stripped it down looking for a vacuum leak internally. To my dismay I found rust on the front half of crankshaft. This bearings and the centre seal were very worn and totally unserviceable. The centre two con-rod small ends are also blued from over heating. The worn seal was allowing crank case pressure to leak between the front and rear chambers (remember the Hirth is a 2-stroke and thus pressurizes fuel/air mix in the crank case), thus causing the engine to run lean and cause over heating. Therefore I am up for a new crankshaft, seal, bearings and gaskets. AU$3500 to AU$4000. The vacuum leak was not evident when cold because the tolerances where closer when cold and the cold oil would help with the seal. The more I ran it the worse it got. The previous own had the Hirth for 4+ years while building the KR2. During this time the engine must have gotten moisture (water) in the crank case, causing the rust. I'm giving the previous owner the benefit of the doubt that he didn't know there was a problem when he sold it me. I didn't rebuild the Hirth because: 1. I couldn't get enough support during the 6 weeks of trial and error diagnostics. 2. I haven't found another Hirth engine user who is happy with their installation. What I learnt from the "experience" -------------------------------------------------- 1. If you are going to buy a second-hand engine pay second-hand prices (the engine was 4+ years old, even though it only had 2 hours on it when I got it, and mug me, paid near new price for it.) 2. If there is evidence of it sitting around for a while, tear it down and inspect before buying. 3. If you are buying something that is not common (the Hirths are not common in Australia), find someone serviced by the same dealer you'll have to use, that is satisfied with their engine and the dealer support. 4. It is real easy to spend money on aircraft :-) and my wife is very understanding. I've learnt, and now have moved on. I feel happier and safer with a tried and proven 4-STROKE engine. Regards Barry Kruyssen Cairns, Australia RAA 19-3873 k...@bigpond.com http://users.tpg.com.au/barryk/KR2.htm
