J400/3300 - Oil Consumption

[shafto]

Once glazed, there is no return other than honing.

Thats what I ment by Martin J400 putting Straight 100 back into the engine, it wont help with fixing the oil consumption. And like you said cylinder bore's need de-glazing/honing or Straight 100 will do nothing.

 

 

[Guest Martin J400]

Further Update....

 

The problem was found to be with Cylinder No 2 (The one with the worst leak down and compression test results). It seems to be a combination of:

 

• The 'gap' in the piston rings were all lined up and stuck in this position. Not an uncommon problem I'm told
   
   
  
• The inlet valve guide was badly worn. I'm told this is probably where most of the oil consumption issue originates from
   
   
  

 

The good news is that there was no evidence of glazing in the bore so presumably run-in was ok.

 

Following rectification work, the max static RPM has increased by 50-75 RPM. A test flight confirmed all running fine now.

 

When I collect the aircraft, I'll monitor the oil consumption thereafter and updated the forum.

 

I suppose the question is, why has an inlet valve guide worn out in 125 hours on a solid lifter engine (incidentally, the exhaust valve and guide was fine).

 

 

[Guest watto]

Hi Martin, I have a J230 and as Brent has said they will blow oil out if to high! I also have just hit the 80hr mark and the oil usage seems to have reduced particularly in the last couple of trips since I have run the engine a little harder than I had been in the past and that has helped to bed things in a little better and the performance seems to be a little better as well.

 

The didgy looking spark plug may well have been damaged when it went in and may not have been burning clean from the start but only a plug change will provide true evidence of that.

 

I understand with a new aircraft it can be a little stressful and you tend to be very watchful (wich is a good thing) but I am sure it will settle down with a little more use and of course some investigation into the issues.

 

Hope all goes well.

 

Watto

 

 

[Guest brentc]

Valve guide wear is not uncommon in solid lifter engines. The last one I know of that had this problem had undersized oil feed pipes to the heads. The small hole that feeds them was increased in size to feed more oil. Another one that I know of with this problem hasn't been resolved, he finds metal under the rocker covers every time he changes his oil. The one I know of that has been resolved was getting approximately 1,000 hours wear in his rocker bushes in approximately 100 hours of engine run time (not good!).

 

A good test to see if you have enough oil getting to your heads is when you are changing your oil, warm the engine to hot, then take off the rocker covers. You should get a bit of a trickle of oil dripping onto the ground (onto your rocker cover that you placed there). The amount of oil will vary but after it's stopped dripping into your rocker covers, it should come close to covering the inside surface of the rocker cover.

 

I've found that one of my heads isn't getting enough oil (number 5 - pilot rear) and I can't work out why. It's almost like the oil feed line is partially blocked but we know it's not. When it drips onto the ground, it would be lucky to be 2-3 drops. I don't appear to have any rocker bush wear however.

 

There was a set of perspex rocker covers floating around with a member of this forum that they used to work out which heads weren't getting enough oil. This might be a potential problem diagnosis if things don't improve.

 

 

[Derby]

Hi Brent number 5 is on the passager side not pilot side. ( sorry for correcting you rory).

 

 

[Guest brentc]

Indeed you are correct Rory (unless my engine is inverted), yes, I should have said number 6, oops. It's been a long day, just got home from work.

 

Atleast someone bothered to read what I wrote :-)

 

 

[BigPete]

Brentc - most of us like to read what you've written:thumb_up: - and just to prove it :big_grin:

 

you need a space between Atleast. (At least). :confused:

 

regards

 

:big_grin::big_grin:

 

 

[Guest Martin J400]

Sorry, one other thing I forgot to mention is that the cylinder base nut modification was done on all cylinders at the same time. This was mentioned in the Dec 2008 Jaba Chat.

 

I'll let the forum know how the consumption goes over the next few months..

 

 

[Guest Martin J400]

Further update... I've flown 10 hours since replacing the inlet valve guide and doing the cylinder base nut mod. Good news is that the engine is runing great.. Bad news is that its still consuming 90ml of oil per hour!!

 

Going back to have it checked as planned (leak down, torques etc.) by engineer. Will let you know..

 

 

[Guest brentc]

It must be catching, I have a leaking cylinder at the block end. aarrrgghhhhh. enough to be a pain and plaster the spat with oil when you leave it overnight.

 

 

[Guest Martin J400]

Further Update

 

Have now done 22 hours since inlet valve guide replaced and cylinder base nut mod completed. It's runnning great but still has approx 90ml per hour consumption. I try to keep the oil level at half way mark but this does mean some oil gets blown out evidenced by some in the bottle and some on the belly of the fuselage.

 

I think I should run the oil at the bottom mark for a few hours but don't really want to risk it! Probably time now to ignore it and just enjoy the flying.

 

 

[Captain]

Have now done 22 hours since inlet valve guide replaced and cylinder base nut mod completed. It's runnning great but still has approx 90ml per hour consumption. I try to keep the oil level at half way mark but this does mean some oil gets blown out evidenced by some in the bottle and some on the belly of the fuselage.I think I should run the oil at the bottom mark for a few hours but don't really want to risk it! Probably time now to ignore it and just enjoy the flying.

I don't claim to be an expert on this and you should check with the factory if you need to, BUT if you are losing oil into the bottle, or more particularly on the belly of the fuse then you have too much in the engine IF YOU HAVE THE OVERFLOW LINE GOING UP BEFORE IT GOES DOWN TO THE CATCH BOTTLE.

 

I normally run my 230 about 1 mm above the bottom of the cross hatched mark on my stick and it works great. Always plenty of pressure, reasonable oil consumption and no issues. On a 3 or 4 hour flight I might go 2 or 3 mm up.

 

If I were you I would trial a 30 mins flight, check it, then an hour or so with the lower level as spec'd by Jabiru .... and see if the consumption drops. If it works then try maintaining that level.

 

If you have the oil level too high you are not doing your engine any favours.

 

Hope this helps. Regards Geoff

 

 

[Guest drizzt1978]

Even in the 170's and 160's at tooradin, Ive been told by the CFI just above the bottom line, other wise if you fill it up the oil use seems to be very high indeed.