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Hydraulic Eng Broken Through Bolts


blueshed
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Hi Guy's

 

the local flying group has oreded a J230, due to arrive in Dec, have noted a few J160's with the hydraulic engine have been breaking through bolts. What is causing this? Some have said that Jab put in hydraulic lifters, however didn't put in a modified hydraulic cam. The J160 seem to be failing at about 300 hours, does anyone know of any J230's with hydraulic motors that have achieved this number of hours.

 

What should we be asking of Jabiru, before we pay and accept delivery of our new aircraft?

 

Looking forward to any thought's ;)

 

Thanks Guy

 

Safe Skies for All

 

 

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I'd just ask them straight up and see what they say.

 

Believe it nor not, the manufacturer of the engine usually does know a lot about it, and if there is a problem then Jabiru will be right on it. After all, they have their corporate future hanging on the success of their engines just as much as their airframes, so they will be investigating the issue most thoroughly. I'd also ask for any advice about torque values for engine bolts throughout the installation. Sometimes manufacturers change torque values after in-service experience shows that such a change is justified and advantageous to the engine/aircraft operator.

 

 

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  • 2 weeks later...

Hi Guy's

 

Had a long chat to Rodney Stiff today about this challenge, seems it is to do with the fuel mixture, as they had adjusted how this being controlled by using a different needle. This was to create the different mixtures required for full power climb, cruise etc. However the equipment being used to monitor the effects was taking an average of what was happening in the different cylinders. Until individual monitoring for all cylinders was used the challenge did not show it's self. Cylinders were running at different temperatures, thus creating combustion challenges, different within different pot's. Setting up a resonance which was ultimately responsible for the challenges encounted.

 

Not really very much to do with the hydraulic lifters at all!

 

Thanks Dieslten and where does this call sign come from?

 

J430 I like the sound of a turbine myself!

 

Cheers Bluey

 

 

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From my understanding and first-hand experience and from those at my airfield, the problem is not only mixture, but oil flow to the heads. We had a case with a 6 cylinder having to be rebuilt because the rocker bushes were dead at 100 hours because of a lack of oil feed to the heads. While they continue to ship out 6 Cylinder J230c's that run at 100 deg oil on a 20 degree day, they will continue to destroy rocker bushes. I note Techmans article this month says there have been problems with poor maintenance and valve issues - I believe this is because Jabiru are suggesting that the problems with the rocker bushes are due to poor tappet adjustment and maintenance. There is so little maintenance required on the new 6's, but yet there are failures? I've just been made aware of a new J230 at Tyabb that's running at near redline oil temps on an average temp day - it's only a matter of time before it fails. There is a simple fix for this so you've just gotta not ignore the symptoms!

 

 

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Guest grantisaac

Hydraulic motor 2.2l with 520 hours, burnt out valve .Worn out rockers. Motor as supplied and jetted by Jabiru and serviced as per instructions.

 

 

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Yet in Westcoast's thread titled " Rotax 912ULS & oil temperature thermostat", he is chasing a system that will get his oil temp up above 82 C and probably up near 100 C at times.

 

I know that the 912 is water cooled .......... but it seems a big difference between the 2 engines.

 

 

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Hydraulic motor 2.2l with 520 hours, burnt out valve .Worn out rockers. Motor as supplied and jetted by Jabiru and serviced as per instructions.

What was your oil temp?

 

And did you have the lip on the bottom of your cowl?

 

 

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Guest grantisaac

Oil temp in the green, cht normal. 500 hundred odd hours or less before valve burns out.Normal.

 

I find it interesting that there are more cylinder bolts breaking out there since i raised this issue a few months ago in a previous post.

 

 

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I have no way of telling on my engine, but this is a known fact that rich of peak EGT is a far more damaging thing than lean of peak. You get a much bigger bang in other words, and if you do some reading about the GAMIjector boys in the US the info is there.

 

Could it be that the ROP problem thy speak of is causing the problem???

 

I would love to know the answer.

 

J

 

 

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Oil temp in the green, cht normal. 500 hundred odd hours or less before valve burns out.Normal.

The trouble is that 'oil temp in the green' may still be too high for prolonged engine running. Running at over 100 which is still in the green will eventually do damage, particularly to rocker bushes. Valves on the other hand are more CHT temp related. I've been harping on about enigne problems for a long time on here with regard to temps and whilst they might ship out an engine at 100+ deg oil temp, their newsletters will tell you not to run them over 80-90 if possible. You've got to get out there and speak to other operators with the same engines and long term experience to get information on the way they should be running. If they are too hot, changes should be made immediately.

 

 

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Hey Mattwhat engine is in your CT4A? Do you do aero's?

 

Cheers Bluey

Sorry Blue, didn't see this post. Our CT4A has a Continental IO-360-H, 6 cylinder, 210HP with inverted fuel and oil systems.

 

Off topic completely to this thread but to answer the "aero's" question...

 

No aeros for me yet but I have started the theory well before getting into the practical...sometime in the near future. As with all new flying adventures, there's a fair bit of theory to be learnt before stepping into the aeroplane and turning it upside down. Focus at the moment is stalls in all configurations, attitudes and speeds. Sounds strange when aeros are normally done at higher speeds, but understanding the behaviour of your particular aircraft at or near the stall and recovering is critical - as we all know, a stall doesn't occur at a specific speed but at a critical angle of attack which can be reached and exceeded at just about any speed.

 

Cheers,

 

Matt.

 

 

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blueshed,

 

"Dieselten" is the nickname (affectionately) given to the DC-10 in all its various series. An airframe chiselled out of solid granite, it went where it was pointed and was a real pilot's airplane, and the CF6 was the most tractable of all the hy-bypass turbofan engines too. Anecdotally, you could slam the power-levers from flight-idle to TOGA and back again and the CF6 wouldn't so much as hiccup, let alone suffer a compressor-stall or something even nastier. Douglas and GE got it right.

 

Talk to the (now ageing) crews that drove it and they'll get misty eyed about the old girl, like the guys who drove the 727s and Diesel Nines do.

 

They just don't make 'em like those good old hulls any more. I'm sorry I only ever pax'd in 'em.

 

 

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I may be wrong, but my instincts tell me that it could be a metallurgical problem, (it won't be the first) not an oil problem. Having said that, there is nothing wrong with being cautious and treat the oil with respect. In particular, Jabiru owners could take a leaf out of the Rotax book and spend a bit more time making sure the engine is properly warmed up before committing aviation.

 

David

 

 

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