Online Community of Zenith Builders and Flyers
Jabiru has been building engines for over 3 decades. I do believe the early engines ("Gen 1") were problematic - they had thicker and fewer cooling fins and gained a reputation for being difficult to cool/overheating. As we all know, once something gets on the internet, it's there forever, so those not in the know will always tell you "they're difficult to cool and overheat." My engine, #2427, was built in the transition from Gen 2 to Gen 3 - it's got some of the Gen 3 upgrades, but not all. It does not have the Gen 3 roller cam or the Gen 3 pistons that have recesses so that if a valve stuck, it won't hit the piston.
I've got nearly 750 hrs on mine over 10 years in my 750 STOL. It did take attention to detail as far as ducting and sealing the cooling airflow, but in this case you're stuffing a 6 cylinder, air-cooled engine into a high drag, low-speed airframe. However, I have no cooling problems - my CHT's run in the high 200'sF with a rare cylinder barely over 300F in cool weather and in hot weather, about half the cylinders run in the high 200's and half between 300-310. That's well below the max continuous CHT limit, which I think is ?356F?
The basic engine seems bulletproof - just change the oil every 25 hrs and go! Some of the peripheral accessories have been replaced - the VDO oil pressure senders seem to last about 200 hrs and I replaced that with a modern solid-state sender which should last indefinitely. The Bendix clutch on the starter fizzled out after a couple of hundred hours - it was a third-party copy of a Honda part. I replaced it with a genuine Honda Bendix clutch and it's been going strong for hundreds of hours.
Jabiru is now up to Gen 4 - the biggest change was going to cast aluminum parts for most of the engine vs the all CNC'd engine of previously and going to all-aluminum cylinders with Nikasil lining rather that steel liners. Knowing what I know now, I'd have no hesitation to buy a Gen 4 engine. It's a dirt simple engine - 120 hp, direct drive, air-cooled, magneto ignition (it'll keep running if the battery fails) and very light - about 180 lbs with all accessories, which is about like the Rotax. Best part, I think they're still around 20K for a brand-new engine with a warranty. It's ancient history now - I bought mine over 10 years ago - but also the FWF kit was very complete and much less than a Rotax FWF kit.
So, all in all, I consider my installation a "success story" and no serious problems.
I have both a 701 with a Rotax 912 and a 601XLB with a camit. The camit is a Jabiru variant. I built the 601 in 2007. It now has 2,696 hours on it and the camit is the third "Jabiru" that has been in the airplane. I believe the 912 is a tougher engine but I much prefer flying behind the smooth Jabiru and much prefer its simplicity.
The camit has 1,149 hours on it with ZERO issues during its entire life and compression is still good (76, 74, 76, 75, 74, 73). Sadly, camit went bust so I have an engine that is past the hours at which a top-end is "required" and limited support, so I am thinking of my options but I am hesitant to go with a gen-4 because I have come to know Jabiru as the company that can't shoot straight no matter how hard they try, although I would love to learn otherwise...
My first Jabiru engine (SN 1256) made it to 906 hours but with major problems, including a top-end at 630 hours. I discarded the engine at 906 hours because of lifter/cam failure which shed metal into the oil and destroyed all the bearings and the crank. When I got the engine torn down I found that the case was badly fretted. Into the garbage bin it went...
My second Jabiru engine (SN 2340) was nearly perfect until I discovered metal in the oil filter at 650 hours and tracked it down to a lifter/cam design issue. The sharp edges of the lifters were ripping out metal on the cam. 10 of the 12 cam lobes were damaged. Very sad because the engine seemed to be in good shape otherwise. When I got the engine torn down to replace the cam, I found minor case fretting. At that point, having spent well over $40,000 with Jabiru, I was done with them and bought the camit "long block" which required moving some parts from the second Jabiru over to the camit to complete it.
So based on my limited experience, I think of Jabiru engines as being good for maybe 1,000 hours, which makes them quite expensive. I would love to hear stories from folks with more than 1,000 hours. Anyone, anyone??? Stories of engines getting to 600-700 hours will not impress, but are welcome.
The early model Jabirus did indeed have issues with cooling and reliability. The later generations have essentially resolved those issues, and Jabiru has offered mods for some of the earlier models that have mitigated them to a great degree. The moral of the story is that most of the negative reports you see about earlier model engines really don't apply much anymore. The problem we have with getting this information is mainly because most of the high time Jabirus are in Australia, and you have to check the Australian forums to get reliable info. The Aussies seem to be pretty happy with them now, though they too had issues with the earlier models, and tended to bad mouth them just like some folks here do. That seems to have dramatically decreased too, according to the reports I've seen from folks who've visited those forums. I've seen nothing but rave reviews for the Gen 4 3300, and plan to put one in my 750. Are they perfect? No. But is any aircraft engine perfect?
I have a Gen 2 engine with 500 hours on my 601XL. Engine runs great. CHT's had to get dialed in while the engine was going through break-in, but once I got the ran air duct baffles where I needed them, no CHT issues at all. The only time I have seen them get hot was during a few 45 minute taxi times to depart EAA Oshkosh on hot days.
I put a single turning vane in the rubber carb intake hose and it helped get EGT's more even across the cylinders. I put in a one size smaller main or needle jet, but I can't recall which now. That helped with an over-rich mixture that Pete K. predicted we would see with a stock Jabiru engine in a 601 airframe.
I have changed the VDO oil pressure sender once for failing to high pressure. The NAPA replacement is going strong so far. I put new rotors and caps on, just because of high time per Jabiru, not for cause.
The only issue, if you want to call it one, is oil seeping out of the rocker lubrication system. My Gen 2 engine has the external oil tubes and rubber T's that feed into the head. I get drips out of the T's that keep the bottom of the cowling and floor well oiled. My oil consumption is still very low, so I have just lived with this issue so far. I bought new T's, but the heads have to come off to replace them, so I have held off on this so far.
I burn 100LL exclusively with the Decalin additive and have not seen any lead issues so far.
So far so good. We will see how this goes as I keep building time. Here is a screen shot of my Dynon showing typical numbers while set up for straight and level economy cruise on a warm day last August.