facthunter Posted August 21, 2015 Share Posted August 21, 2015 You won't believe me, but I was going to suggest the seat but it's something you notice straight away, when you remove the head. When they are installed the interference is about .005" depending on the diameter. Aluminium expands more than the nickel iron alloy in the seats. If the fit isn't tight enough it falls out and usually jams crooked or breaks into pieces. Some fit them using liquid nitrogen to shrink the seat in aluminium alloy heads to ensure no damage when installing. Maybe it wasn't tight enough or been overheated. Nev Link to comment Share on other sites More sharing options...
SDQDI Posted August 21, 2015 Share Posted August 21, 2015 This weekend I flew over 1200km with my 500 hour Jabiru 2200 engine, a fair bit at low level looking for feral animals. The engine just purred as always, as it has for the past 14 years. And yes I tweaked the cooling, but the engines have all the tweaks I did built in these days. At Bordertown I was told by a guy (who has obviously kept himself informed) that my engine would fail soon. ...Bruce I hope you buy that fella at Bordertown a drink Bruce:wink: I know this post is below the belt and is not really decent but I do have a weird sense of humour (some people say I have no sense of humour, actually some say I have no sense!) I really am a friendly person and all my digging is meant to be friendly ribbing, I have friends that own jabs. Also I don't want to stop people posting about problems so please don't take this too much to heart. I had a through bolt failure on my 914 that I posted about on here, so we aren't perfect either. Anyway so you get the point I sort of feel a little guilty about this post but I just couldn't resist. Link to comment Share on other sites More sharing options...
SDQDI Posted August 21, 2015 Share Posted August 21, 2015 This weekend I flew over 1200km with my 500 hour Jabiru 2200 engine, a fair bit at low level looking for feral animals. The engine just purred as always, as it has for the past 14 years. And yes I tweaked the cooling, but the engines have all the tweaks I did built in these days. At Bordertown I was told by a guy (who has obviously kept himself informed) that my engine would fail soon. ...Bruce I hope you buy that fella at Bordertown a drink Bruce:wink: I know this post is below the belt and is not really decent but I do have a weird sense of humour (some people say I have no sense of humour, actually some say I have no sense!) I really am a friendly person and all my digging is meant to be friendly ribbing, I have friends that own jabs. Also I don't want to stop people posting about problems so please don't take this too much to heart. I had a through bolt failure on my 914 that I posted about on here, so we aren't perfect either. Anyway so you get the point I sort of feel a little guilty about this post but I just couldn't resist. Link to comment Share on other sites More sharing options...
Bruce Tuncks Posted August 22, 2015 Share Posted August 22, 2015 Hi SDQDI, well I don't agree the engine failed. It just ran rough and I had a look why. Not bad after 14 years . It was till running when I turned it off. Now Nev says it needs all 4 cylinders to stay up, and I respect his opinion, but a Jabiru only needs 30 kg of thrust to keep on level flight. I'm not going to do the experiment though. My Libelle needs 10 kg of thrust and flies with no engine but I admit it comes down. Anyway, the safety feature of all our light planes is NOT the reliability of the engine, it is the low stalling speed. No offence taken, I am pleased you actually remembered an old posting of mine. Nev, I reckon you are right that it must have been heat. I was running it on the ground using the dynamic balancer and this cylinder head ( no. 4) must have got hotter than I thought. Hotter than in normal flying anyway. 1 1 Link to comment Share on other sites More sharing options...
facthunter Posted August 22, 2015 Share Posted August 22, 2015 The heat will bring out the fault which is the insert is not tight enough. That could be that it has previously overheated, never had the right fit or the head metal is not that good in specification. I think the later CAMit material is superior (Someone can confirm that). Any heat treatment will be lost if the heads go above about. 250 C. ie they will be softer and that will apply to the hottest areas near the exhaust valve. I don't know what heat treatment the heads are subject to or whether the billet they are made from is the determining factor. Nev Link to comment Share on other sites More sharing options...
fly_tornado Posted August 22, 2015 Share Posted August 22, 2015 the Jabiru hits the magic 500 hour mark and automatically wants to migrate to bundaberg for a 3 week holiday 1 1 Link to comment Share on other sites More sharing options...
Oscar Posted August 22, 2015 Share Posted August 22, 2015 Nev: No heat treatment; Yes, the CAMit alloy has superior heat handling capability; the standard Jab. heads are toast if run over about 220C; Jabiru J120 POH states absolute maximum 200C for take-off, 180 C normal, only 5 minutes max. allowed above 180C, ground running 180C max. In ground running, it is very easy to get reversal of airflow into the cowl if there's a crosswind. Link to comment Share on other sites More sharing options...
facthunter Posted August 22, 2015 Share Posted August 22, 2015 If they were exterior coated with a heat related colour change paint it would give positive indication the head has been overheated. It's a "once it happens, it doesn't fix itself ,"situation even if the motor is operating seemingly. OK Nev 1 1 Link to comment Share on other sites More sharing options...
Oscar Posted August 22, 2015 Share Posted August 22, 2015 HA! - we've been talking about doing exactly that with CAMit!. But not a total coating - the damn paint for it is INCREDIBLY expensive; with the 'dangerous goods' transport charges, I think we found it to be something over $200/litre!. So, maybe a few 'dobs' in critical places, and we'll be searching for those places as part of the test cell work, using stick-on temp. indicating strips. Also, the possibility that the paint itself might cause undesirable changes in heat dissipation would need research all on its own.. We go over this ground in Jab. engine threads time after time, and some don't want to believe it ( and to be entirely fair, Jabiru have, I feel, used 'overheating' as a reason for problems far too liberally, when it has been a combination of circumstances), but cooling is the Archilles heel for Jab. engines. Ask any aero engineer about engine swaps in aircraft and they will tell you that achieving acceptable cooling performance is quite often the biggest single headache; the structural elements for an engine swap are (usually) handled fairly easily, particularly with advances in FEA software. Cooling performance is simply NOT intuitive; it took over 12 months of careful testing, for instance, to get the Motor-Falke engine swap to a Jab. 2200 to work properly. What 'looks' right, just does not necessarily work right. Bruce's experience of 14 years of trouble-free operation says to me that he has set up his installation well, has operated his engine carefully and has undertaken his maintenance scrupulously (and the picture of his head says to me that is has absolutely NOT suffered from any form of 'abuse': it is marvelously clean and deposit-free - I've seen heads with nearly 1/8" of caked lead on them in places, (that were still actually running ok!). But, as you have pointed out - one over-temp situation degrades the alloy, and from thereon in, it's all downhill. As Bruce has stated, his ground runs were 'exceptional' (though I suspect that the vibration he had experienced indicated that that #4 head was on the way out anyway, and his preventive maintenance action simply confirmed - in a rather dramatic way - that fact, rather than in any way caused it). Those who have followed the various Jabiru engine threads will know that some operators have a history of continual 'early' failures ( and I have log-books that show my own aircraft was amongst those when operated by a FTF, though other evidence I have discovered on the aircraft says the maintenance by an L2 was extremely flawed), while others operating in ostensibly the same way have reliable histories of very good engine life. Any statistician will tell you that such variance indicates factors beyond 'circumstance' as the determinant of results; if we were all really serious about getting to the bottom of the Jab. engine problem issue(s), we would be compiling an exhaustive picture of 'operation' with all the important factors recorded. FWIW, the recent initiative by Jabiru to develop a risk 'profile' and a resulting schedule of inspection is a move probably about 10 years later than it should have been instituted. However, it does not 'audit' cooling performance, nor does it require data collection on key factors such as CHT and EGT ( for all cylinders) on a continuous basis. Lycoming nowadays requires an audit of any new installation before they will 'clear' the engine for warranty purposes - and they conduct the audit! Once you have passed that audit, you cannot change anything on the installation without Lycoming's approval or the warranty is void. As a long-time motorcyclist, I know other motorcyclists will recognise the analogy I here present: Volvo drivers were traditionally so secure in their belief in the safety of the vehicle., that they never bothered to look around them. Well, perhaps the same syndrome carries over to recreational-class aircraft: those who simply require the engine to 'keep running', without care in maintenance and operation, should buy a Rotax 912-powered engine: be happy to pay the extra cost of purchase and operation and the reduction in weight available for airframe safety. If you buy a Jabiru-engined aircraft, then you need to get more 'involved' in operation and maintenance issues. Anybody who has read 'Zen and the Art of Motorcycle Maintenance' will recognise the division between those who do not want to get their hands 'dirty' with mechanical issues, who expect that since they have paid the money, as a result it is not their concern for the operation: turn the key, go. Those in that category SHOULD NOT buy a Jabiru-engined aircraft. If you are killed in a less-crashworthy airframe IF the Rotax fails - well, you aren't around to complain, are you? 3 1 1 Link to comment Share on other sites More sharing options...
deadstick Posted August 23, 2015 Share Posted August 23, 2015 Hi Bruce, exact same thing happened to one of my Jabs, was a J160 with full CHT monitoring. Was being used at an FTF and during the pre take off power checks started running rough. Interestingly three heads had cracks in the intake runners if I recall correctly! Link to comment Share on other sites More sharing options...
stuartmspencer Posted August 23, 2015 Author Share Posted August 23, 2015 My threads been hijacked lol! Seems like there isn't much experience of the latest roller cam iteration of the 2200 within this forum. I have ordered the Jab engine however, and hopefully will have it fitted this week. Am sincerely hoping they have sorted everything out with this latest engine. 2 Link to comment Share on other sites More sharing options...
deadstick Posted August 23, 2015 Share Posted August 23, 2015 Sorry Stuart, on topic yes I have a roller cam 3300, got just over 100hours on it and looking good. They are a breed away from the last iteration, run smoother and have less engine noise. If your any where near Tamworth I'm happy to take you for a local flight. 1 1 Link to comment Share on other sites More sharing options...
stuartmspencer Posted August 24, 2015 Author Share Posted August 24, 2015 Thanks deadstick! I am in the UK otherwise I would take you up on that offer. ;-) Am glad to hear you are having a good run with your engine. Let's hope we have good lives out of ours. I've also heard they produce a bit more power than the early hydraulics. What aircraft do you have yours in? Did you see a difference in climb performance? Link to comment Share on other sites More sharing options...
deadstick Posted August 24, 2015 Share Posted August 24, 2015 It's in a J230-D, I don't know about extra power but it runs cooler than my previous flat hyd lifter. Only had 2 issues thus far, a leaking mechanical fuel pump, and a lifter that pumped up holding the exhaust valve off its seat slightly. Link to comment Share on other sites More sharing options...
Bruce Tuncks Posted August 24, 2015 Share Posted August 24, 2015 Hi Stuart, sorry to hijack your thread, but unless they have managed to change the different expansion rates between steel valve seat and alloy head, then this could happen to your new roller-cam engine too. Don't get the heads hot! Read Oscar's and Facthunters posts. That's the key to reliability, which was in the title of this thread. Now to continue the hijack with some news..my plane is flying again. I tapped the valve seat back into place, ( It took a lot of force.. there is quite an interference fit there, at least when the temperatures are the same on both the seat and the head) . Then I peened around the seat with a centre-pop, leaving dimples around the seat about 1.5mm out and 6mm apart. The idea of this was to increase the compression force onto the seat. Surely ( I hope) more compression than before it fell out. Next I lapped in the valve, did a leakdown ( 80/65 cold) , did a ground run , and went for a test-flight, staying in glide range of the field. It went fine, but being cautious, I took the head off again to find that the seat had not moved. Actually, the engine seems smoother now. Maybe Oscar's thought that this seat maybe could have been the source of the rough running impression was right. I still want to use that Dynavibe meter, but not on the ground. So it will need a very good installation to be airworthy. Running up to 2800 rpm on the ground is a nasty business , the plane is straining against the brakes and there is too much noise and ( I now reckon) too much heating. And yes I'm starting to save up for Camit heads. Link to comment Share on other sites More sharing options...
deadstick Posted September 18, 2015 Share Posted September 18, 2015 One dynamically balanced 2200 flywheel for a friend. 1 Link to comment Share on other sites More sharing options...
Oscar Posted September 18, 2015 Share Posted September 18, 2015 You ARE having a bit of a joke - right? To be dynamically balanced as a flywheel, it requires to be mounted onto the crankshaft on which it is used and referenced as to mounting. Are you including the actual crankshaft in the offer? 1 Link to comment Share on other sites More sharing options...
deadstick Posted September 18, 2015 Share Posted September 18, 2015 Lol, no mate just the flywheel! Seriously and no jokes!!! Your basing that statement on your 'in depth' and 'vast' experience in jabiru aero engine building I take it? Link to comment Share on other sites More sharing options...
facthunter Posted September 18, 2015 Share Posted September 18, 2015 You are being a bit hard Oscar. If everything runs true, the parts can be balanced individually, and the end result is good. I would suggest you don't put the holes so close to the base of the gear teeth though (next time). Nev. Link to comment Share on other sites More sharing options...
Oscar Posted September 18, 2015 Share Posted September 18, 2015 Lol, no mate just the flywheel! Seriously and no jokes!!! Your basing that statement on your 'in depth' and 'vast' experience in jabiru aero engine building I take it? No, just the physics involved. Link to comment Share on other sites More sharing options...
Oscar Posted September 18, 2015 Share Posted September 18, 2015 You are being a bit hard Oscar. If everything runs true, the parts can be balanced individually, and the end result is good. I would suggest you don't put the holes so close to the base of the gear teeth though (next time). Nev. Balanced individually, is not dynamically balanced to the assembly. An assembly of individually balanced components can statistically allow the sum of the worst tolerances to align. In the case of the crankshaft to flywheel assembly - especially with reference to the harmonics in the crankshaft at certain frequencies - it is the assembly rather than the individual components that needs to be tested. 1 Link to comment Share on other sites More sharing options...
deadstick Posted September 18, 2015 Share Posted September 18, 2015 Hi Nev, it's not my work mate it from Camit, I don't have the gear and a little bit out of my comfort zone to be playing around with flywheel balance on an engine that's been plagued with issues. And yes Oscar it's dynamically balanced! or am I missing the physics and all? LOL Link to comment Share on other sites More sharing options...
deadstick Posted September 18, 2015 Share Posted September 18, 2015 No one mentioned 'the assembly' Oscar! In fact Ian stated that it was not required, go figure I trust he knows better than I in this topic. Are you ever positive or helpful? You come across as downright nasty and spiteful, though it can be hard to accurately read tone in a typed statement. Link to comment Share on other sites More sharing options...
facthunter Posted September 18, 2015 Share Posted September 18, 2015 Oscar, I don't agree. Harmonics is length and mass to stiffness considerations, None of which you are correcting or measuring. It's not practical to rule out individual component balance. I did say if everything runs true. Balancing an assembly means you must continue to do it that way. as only the final outcome is assessed. Any change to the position of components with your method is bound to result in an unbalance.(in principle) Nev Link to comment Share on other sites More sharing options...
diesel Posted September 18, 2015 Share Posted September 18, 2015 Dropped valve seats in engines has always been there. Not just Jabaru. Its been 40 years since my last one. A Chev corvair in my Vee Dub. Yes the bits sucked all around. Thr heads can be undercut to prevent this. Check William Wynes fly corvair collage for a modern fix. Chas 1 Link to comment Share on other sites More sharing options...
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