Oil Leak on cylinder base nuts

·         matthew dovey

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Hi Doug,
Wonder if you can help. I've been fixing an oil pressure problem on my 2200 solid lifter. Pretty much sorted the pressure problem but while I was troubleshooting noticed the rear cylinder bottom hold down nuts leaking oil. I've torque checked the nuts and they didn't move (engine was still warm). If the through bolts had failed then I should have been able to rotate the nuts before they reached the torque of 35lbs. I'm going to do another torque check when the engine is cold. Have you come across this problem. Is it oil leaking from under the bolt head, tracking up through the threads or something worse. The bolts are 3/8 with the ms style nuts which have only been on there for a year and a half.

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·         Doug Smith

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Hi Matthew,
Oil leaks from the cylinder bases of a solid lifter 2200 (particularly one that isn't in a flying school) are usually not an indicator of anything serious. Historically, we'd monitor the leak and, if it got too bad we'd remove the barrel (or partially remove it - it is possible to do the job without removing the piston from the barrel of you're careful), replace the o-ring, apply some fresh goo and bolt it back together.
On the odd occasion it can be an indication of stress in the engine - possibly detonation or loosening through bolts - but if you've checked the bolt torque and it's ok then chances are it's not in this case.

But, in the interests of being thorough, a few questions :
1. What airframe is it in and what prop are you running?
2. Are you using the standard carby and standard tuning?
3. How many hours on the engine?
I'm a little curious as to why you fitted the MS21042 style nuts a year an a half ago... Did you have the engine apart for another reason? Any particular reason you stuck with those nuts and not the 12 point type?

Regards,
Doug.

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·         matthew dovey

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Hi Doug,
Sorry for the late reply. I checked the torque again when the engine was cold. All nuts including the leaky one were good.
I've got about 336 hours on a solid lifter engine with the standard small card. Running a GT prop.
I had the barrels off when I changed the heads. I didn't see the point in changing to the 12 point nuts. It would have meant changing the stud and through bolts on top of the cost of the heads etc.
Any way I'm on to the next Jabiru problem. I have since found the wing bushings are loose. So you will be getting an order for repair bushes coming your way Monday

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·         Doug Smith

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Fair enough Matt.
Assuming the bushes have come loose in the fibreglass wing lugs, they can usually be cured by removing, cleaning and re-installing with some proper epoxy resin (not 5 minute) - no new parts required. You do need to be very particular about surface prep, cleaning etc but it's not rocket science 🙂
Regards,
Doug.

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·         matthew dovey

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Hi Doug,
Doesn't look like I can use the old bushes. I managed to unwind one of the bushes and measured the internal diameter. Lot of slop. Also the aircraft had a quick release wing removal system so instead of 5/16 bolts there were 3/8 mild steel pins. Are you able to make the wing repair bushes with a 3/8 hole instead of 5/16. I might be able to use the fuselage bushes then.

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·         Doug Smith

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Which parts of the quick release system have been removed (a photo might be easiest next time you're near the plane)? Depends what's been replaced as to what can be done now...
D.

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