Jabiru engine life times

[motzartmerv]

I agree and reckon this forms part of the problem with discussions on this issue. What some see as breakdown others see as normal maintenance.

Again.. Is the engine serviceable or not. Thats the perameter. And I spose one could argue that some people would fly with one pot way down on compression..;)

 

 

[motzartmerv]

Have added 1000 hours with no breakdown.

 

 

[facthunter]

Flying with one pot down on comp is not the right thing to do. I don't think even Jabiru expected their engine to go 1000 hours without having the heads off. It used to be called a "TOP' (overhaul) No small engine did it.

 

Thr Rotax does because of the liquid cooled heads and valves that are many times the price of those in a Jabiru. You can get away with it on a car because they are loafing., by comparison.

 

When TAA had Convair 240's the engineers used to run under the wing and listen for crook exhaust valves when they were taxiing in. Nev

 

 

[metalman]

To be fair there should a similar poll for 912's,,,,,,of course you would need a 2-3000 hours option,,,,,,,

 

Met

 

 

[Guest Error404]

Rotax valves are near $240 I believe and Jabiru ones are around $40. In reality Jabiru valves are a quick replacement job including lapping. I can get a head off in about 20 mins, replaced and lapped in and running within 2 hours. Not a huge investment a couple of times prior to 1000 hours when charged for a days work.

 

The complexity is when the pistons choke up however since the new pistons with the wider ring gap this has become less of a regular chore.

 

 

[motzartmerv]

Ive never even seen inside a rotax head.

 

 

[Sapphire]

FH said: Valve guide play should be checked each time the heads are tensioned. It can be done without removing the heads. Nev

 

The valve guides have a strict tolerence with the exhaust guide having more clearance. Continental don't give any specs to wobbling the valve as car manuals do.

 

 

[metalman]

Mmmmm, I'll not get to far into this, it would be good to hear how people are getting the jab engines to last , I'd really like a 3300 in a Kitfox if I thought it would give me the hours the manufacturers says it will.

 

 

[frank marriott]

Hard to get a true sample here for example within 30nm of me there are 10 Jabiru aircraft all of which are between 70 and about 800hrs without a breakdown, but do not fit into the survey as they haven't broken down. Add to that, as far am I am aware, I am the only one of them that even visits this forum and my input is decreasing.

 

 

[motzartmerv]

True Frank. At the time i was hoping more people who run jabs would post. The idea was to get some idea about pure statistics.

 

I entered 2 aircraft (from memory). One had an issue at 40 hours, but then didnt have a problem for the subsequent 800 hours.

 

But then another aircraft had numerous issues, multiple component failures at different times.

 

 

[frank marriott]

No worries, I was just pointing out the small sample - very hard to obtain useful stats on a forum, at least the way I see it anyway.

 

 

[Russ]

400hrs, 2 soft cyls, pulled off all 4 pots, 2 pistons stuck rings, hone pots, replace all rings, reface, reseat valves.

 

Runs sweet as. Private use only, avgas only. Have just " modded" bottom cowl lip (created more efficient suction ) drag out that hot air within engine compt, immediately noticed lower head temps, by a fair margine.

 

 

[Peter008]

Russ - Could you post a couple of pictures of the bottom cowl lip that you modified please? It will be interesting to see.

 

Cheers

 

 

[Guest Maj Millard]

The poll doesn't do it. If it lost compression on one cylinder, at 500 hours and had to have the head off, what would that be classified as? A breakdown?

Unschedualed maintenance..............Maj

 

 

[Jabiru7252]

Unfortunately one cannot answer the questions as one would like, what about an engine with 500 hours and no break downs or issues?

 

 

[Bob Llewellyn]

I'm looking forward to seeing how things pan out when there are a lot more replies.It looks like ruffasguts is getting quite good service out of them, but surely it shouldn't be necessary to pull the heads off every 100hrs to keep the things purring. I thought it was mainly hellies that had high maintenance?

Good on him if he's got those hours out of them, but surely if the manufacturer claims 1000hrs between overhauls, one should not be expected to give a head-*** every 100hrs.

 

Yenns reply was interesting, in that he appears to have had few problems until he was unable to get avgas, maybe they run cooler in the head area with that fuel, and that gives the valves and rings an easier life.?

 

I sometimes wonder whether an additive like Redex upper cylinder lubricant in the fuel would be an advantage, and keep things a bit better lubricated, reducing friction heat?

Pulling a head is a "top overhaul", and Lyconental do not consider it to be a major overhaul - eg tops at 1000 hrs, 2000 hr TBO. Personally, after reading NACA technical Note 4161, I'd run AMSOIL (Alkyl Modified Silicone OIL) in any aircraft engine I could; massively better lubricant at higher temps and operating pressures.

 

 

[Jabiru7252]

So Bob, no disrespect intended here, would you run that oil in a Jabiru engine? That oil get's no mention in their documents and manuals as far as I can tell. If you ran that oil and the engine blew up, who's fault would it be? (So far the only info using Google is from China!)

 

 

[alf jessup]

Rotax valves are near $240 I believe and Jabiru ones are around $40. In reality Jabiru valves are a quick replacement job including lapping. I can get a head off in about 20 mins, replaced and lapped in and running within 2 hours. Not a huge investment a couple of times prior to 1000 hours when charged for a days work. The complexity is when the pistons choke up however since the new pistons with the wider ring gap this has become less of a regular chore.

It's not a huge job for a Rotax either if your not touching the heads for 2 to 3 thousand hours or more. that's 20 to 30 years for a pilot who does 100 hours a year like myself.

 

Alf

 

 

[Bob Llewellyn]

So Bob, no disrespect intended here, would you run that oil in a Jabiru engine? That oil get's no mention in their documents and manuals as far as I can tell. If you ran that oil and the engine blew up, who's fault would it be? (So far the only info using Google is from China!)

Yes. Check out the NACA report. Jabirus do not have a massive habit of dropping valve heads, or valve springs going soggy, and the overpumping of the hydraulic lifters should have been solved for years (some solid lifter engines get valve leaks too). Ergo, the head lubricant is getting too hot / thin. The extra 50C or so the Methyl Silicon gives over any parafin, together with the reduced rate of 'cracking" of the oil, and the increased high-temp viscosity, all should tip the balance. Jabiru is not a research organisation, and their engine is not rocket surgery; and better lubrication (in both a hydrodynamic and a chemical stability sense) doesn't hurt an Otto-cycle engine.

ps I'd want to know a little more about the manufacturer, if the source was Chinese (have met some QC issues with aviation products from Chinese companies...)

 

 

[Jabiru7252]

When I learnt to fly back in the early eighties the average private pilot clocked up 500 hours in a lifetime. Recreational flying has certainly made an impact on those figures!

 

 

[coljones]

Not a big sample to go on, but only 27% of engines making it past 500 hours is a worry!

There is no option in the survey for counting engines that have had no failures. There may be 10,000 that have had no probs at all with at least 5000 beyond 2000 hours. A small sample size OF ENGINES WHICH HAVE FAILED in this survey indicates only that it is a small sample and may not be representative of any or all Jab engines.

 

 

[alf jessup]

School I trained with had 2 x J160's, 1 had all valves replaced as 2 pots were soft at 450 hrs and the other had valves done on one pot at 480 hrs, maintained to Jabs maintenance schedule and run on avgas all the time.

 

Alf

 

 

[coljones]

Only 30 failures out of the entire Jab Fleet - absolutely fantastic!! This sounds a hell of a deal and the go to engine.

 

 

[Jabiru7252]

Yes. Check out the NACA report. Jabirus do not have a massive habit of dropping valve heads, or valve springs going soggy, and the overpumping of the hydraulic lifters should have been solved for years (some solid lifter engines get valve leaks too). Ergo, the head lubricant is getting too hot / thin. The extra 50C or so the Methyl Silicon gives over any parafin, together with the reduced rate of 'cracking" of the oil, and the increased high-temp viscosity, all should tip the balance. Jabiru is not a research organisation, and their engine is not rocket surgery; and better lubrication (in both a hydrodynamic and a chemical stability sense) doesn't hurt an Otto-cycle engine.

I have read this post a few times but cannot make sense of it. Obviously I have had a mini-stroke and need to have a Bex and a lie down. Does it read 'right' to others out there? Will check in tomorrow for responses and abuse.

 

 

[Bob Llewellyn]

I would further check the valves and castings of the cyl head by blocking off the open end with a piece of flat metal and rubber seal. Fit an air hose connection through the metal, turn on that air pressure full blast and listen for leaking air anywhere. Faint leaking out the intake and exhaust ports is ok, but elsewhere is cracked casting.

Since the Jab heads were billet, last time I looked