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Recommendation please

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Recommendation please

Postby Anonymous » Tue Feb 10, 2015 9:59 pm

Posted by: Greg on 10:22:48 10/07/12 Sun

My engine's top end needs some work. I'm based in the West Midlands and would prefer to get it done locally if possible. Can anyone recommend a good engineer with Jabiru experience?

Thanks,
Greg
Anonymous
 

Re: Recommendation please

Postby Anonymous » Tue Feb 10, 2015 9:59 pm

Posted by: Greg on 11:45:36 08/24/12 Fri

Please ignore this request guys. After reading through the Jabiru workshop manual regarding the top end overhaul and what it involves to do it right, I've decided to take it to Gary Cotterell.

Cheers,
Greg
Anonymous
 

Re: Recommendation please

Postby Anonymous » Tue Feb 10, 2015 9:59 pm

Posted by: john grant on 20:22:49 08/24/12 Fri

Good choice. He's the best.
Anonymous
 

Re: Recommendation please

Postby Anonymous » Tue Feb 10, 2015 9:59 pm

Posted by: Gary Omer on 13:08:05 08/27/12 Mon

Hi, what issues do you have. I have 1 cylinder No1 leak down to 64/80, so thinking of getting the top done on that 1. the others are around the 70/80 psi mark
Cheers
Gary Omer
Anonymous
 

Re: Recommendation please

Postby Anonymous » Tue Feb 10, 2015 9:59 pm

Posted by: DL on 14:51:15 08/27/12 Mon

60/80 is the limit. 64/80 is still within specs (although the lower end).

Is it inlet/exhaust valve or is it leaking between piston and bore? To test that you will need a stethoscope (available from ebay) to listen for hiss (air leak) out of the exhaust (exhaust valve leak), the mouth of the carb or air filter (inlet valve leak) of out of the oil filler cap (leak between piston and cylinder).

If it is either of the valves, the general consensus is that you act with urgency. If it is rings, then i can probably wait.

disclaimer
The above are my personal views and should not be used to influence judgement or decisions concerning the state of your engine of your aircraft.
Anonymous
 

Re: Recommendation please

Postby Anonymous » Tue Feb 10, 2015 9:59 pm

Posted by: Greg on 18:08:17 08/27/12 Mon

Hi,

Although it seemed to be running ok, the engine has been using more oil lately - and cylinder number 3 has developed black oily spark plugs. Pulling the prop through before start up showed some discernable differences in compressions. Taking the rocker covers off revealed some brown marks around 2 of the exhaust valve guides. This has happened over a short period of time so I arranged to borrow a leakdown tester.

(Although I'd warmed the engine up beforehand, by the time my mate arrived with his tester, the engine had cooled down again quite a bit which could've lowered these readings. Even so, they would've still been on the lower limits.)

No 1 cyl 58/80
No 2 cyl 62/80
No 3 cyl 57/80
No 4 cyl 72/80

No 3 cylinder exhaust valve could be heard leaking during the l/d test which prompted me to get it looked at asap before any serious damage gets done.

The engine's done 490 hrs now (Solid lifter no 769) and been serviced regularly in the 3 years I've owned it. I bought the aircraft with 117 tacho engine hours on it, so it hadn't been flown much by the first owner in the previous 8 years. I think that's where the problem lies. According to the logbook, during that time, the engine was only started up for periods of 10, 15 or 20 minutes with the longest logged flight being just over an hour. Since owning a Jab, I've learnt that these engines like to be worked hard from the outset, so maybe that's why this engine hasn't reached the expected 1,000 hour top end overhaul time.

Never mind, I've taken 769 out of the aircraft today and it's ready to go over to Gary's in the morning.

Cheers,
Greg
Anonymous
 

Re: Recommendation please

Postby Anonymous » Tue Feb 10, 2015 9:59 pm

Posted by: Gary Omer on 20:19:00 08/27/12 Mon

keep us posted on what needed doing.
was it much hassle dropping the motor out? is it a jab airframe?
Cheers
Gary O
Anonymous
 

Re: Recommendation please

Postby Anonymous » Tue Feb 10, 2015 9:59 pm

Posted by: Greg on 23:48:36 08/27/12 Mon

Jabiru 450UL aircraft and easy to remove the engine. I took some photos of the wiring before I labelled and disconnected it. It was originally done very neatly and I wanted to make sure it went back the same.

I had the use of a small engine hoist on wheels which was used to support the engine before removing the 4 engine mounting rubbers and bolts. Not really needed because the engine remains on the mounting until you pull it forward and lift it clear with assistance, although it will make replacing the engine much easier and can be one man job.

Cheers,
Greg
Anonymous
 

Re: Recommendation please

Postby Anonymous » Tue Feb 10, 2015 9:59 pm

Posted by: Ralph T (Engine work) on 23:05:39 09/05/12 Wed

Apart from mending your engine for what ever it is suffering from, does anyone know when this UL94 fuel comes on sale because many jab engines will not require updating, am told. and that would be nice.
Anonymous
 

Re: Recommendation please

Postby Anonymous » Tue Feb 10, 2015 9:59 pm

Posted by: Greg (:-)) on 21:27:08 10/03/12 Wed

Jobs all done and flying again :-)

All 4 exhaust valves were renewed and lapped in. Inlets were ok so didn't need replacing. The combustion chambers were reprofiled to the later spec. while the heads were removed. The flywheel bolts were renewed and the newer 12 point cylinder nuts have been fitted. Gary managed to turn it round within two weeks and I've done 4 hours since refitting it a couple of weeks ago. Nice to see that an annoying oil leak has also disappeared since having the work done. If I manage to fly another hour tomorrow, I'll check the head torques and valve clearances on Friday.

It does run noticeably smoother than before, probably due to the equal compressions on all cylinders now and the fact that all the rubber engine mountings have been renewed on refitting. Thanks to Gary's knowledge, the top engine rubbers are now fitted the right way round and that should hopefully help stop the swelling/distortion of the top rubber mount. As a bonus when removing the engine, exhaust pipes and cabin heat scat pipes, it was found that one of the oil cooler braided hoses had been chafing against the square edge of the engine back plate, resulting in the braid being worn away - together with some of the wall of the rubber pipe inside. Replacement braided hose now fitted and protected with a short length of thick clear plastic tubing to stop the same thing happening again.

For less than the cost of my insurance claims excess (and all the hassle of aircraft recovery etc. that comes with unplanned landings) I'd like to think I've increased the odds of the engine reaching the first 1,000 hours without any serious problems.



Cheers,
Greg
Anonymous
 

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