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O-235 Oil Leak ID Line-Up!!

Your oil control rings are worn out pumping oil into the combustion chamber where it is being mostly burned.
Wash down the engine to remove all of the wet oil from the outside. Then fly it once around the traffic pattern and look for the oil leak. If you fly it too much the oil will spread around making it difficult to find the leak/s.

Would a decent ground run (with the cowls on or off?) also be enough to generate the leaks? AND without the 80mph plus slipstream to spread the oil around? :)


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That doesn't seem to work as well as a full power takeoff and climb to pattern altitude with a trip around the pattern.
 
OK, I’ll give it a go next week :) New 6131 tailwheel going on end of week and then we’re good to go :)

Ian, my engineering mentor, has suggested some cylinder work we/I can do to help on the oil blow by, so I may well do this as a first and fun step :)


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Would a decent ground run (with the cowls on or off?) also be enough to generate the leaks? AND without the 80mph plus slipstream to spread the oil around? :)


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Maybe a silly question, but do I need to remove the baffles to give it a really good clean? Or just the cowls and then clean it with cloths/paper towels and spray on degreasers? [emoji849]


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Just wash it down with a solvent to get the mess off. Then with the short flight you will be able to see where the origin of the leaks are. Though it does appear that the biggest culprit is burning.
 
Just wash it down with a solvent to get the mess off. Then with the short flight you will be able to see where the origin of the leaks are. Though it does appear that the biggest culprit is burning.

Now I’ve fitted the longer oil filler, I’m pretty relaxed about pouring oil in just to be burnt :) It’s the wiping oil off my lovely clean plane that I really don’t like!!


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Another thought, are you filling the oil to the top or leaving it a quart low? A lot of plane are happy running a quart low. Sometimes just filling to the top throws out the first quart, though I don't think it will be that simple for you.
 
Another thought, are you filling the oil to the top or leaving it a quart low? A lot of plane are happy running a quart low. Sometimes just filling to the top throws out the first quart, though I don't think it will be that simple for you.

I’ve been operating around the 5 mark, so plenty of space below max and only doing short test flights mainly. Now I can pour oil in more easily, I’ll be setting 5.5 as the level and topping up to that


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Does anyone know the part numbers, description and maybe suppliers for the O235-C piston ring sets please? and what other items are good to change at the same time? :)
 
Do you know that your pistons are not damaged? That your valves are reusable, that the valve guides are good, that the valve seats are good....etc...........? Don't even think of ordering parts until you know everything that you need, especially when you have to place your order half way around the World. Are your cylinders standard diameter or oversize?? Did a broken piston ring gouge the cylinder wall beyond limits? One you take it apart you are committed to spending £. I'll let someone else get you a source.

Your engine is 1800+ hours, who really knows what is inside?
 
Do you know that your pistons are not damaged? That your valves are reusable, that the valve guides are good, that the valve seats are good....etc...........? Don't even think of ordering parts until you know everything that you need, especially when you have to place your order half way around the World. Are your cylinders standard diameter or oversize?? Did a broken piston ring gouge the cylinder wall beyond limits? One you take it apart you are committed to spending £. I'll let someone else get you a source.

Your engine is 1800+ hours, who really knows what is inside?

Great advice as always :) I'm not thinking of doing this work any time soon and when I do, I'll definitely be checking (having them checked) all the bits and only ordering afterwards when we know what's what :) I'm just checking that the parts I know about (the rings) are available, before I even consider doing anything else on this track :)
 
Great advice as always :) I'm not thinking of doing this work any time soon and when I do, I'll definitely be checking (having them checked) all the bits and only ordering afterwards when we know what's what :) I'm just checking that the parts I know about (the rings) are available, before I even consider doing anything else on this track :)

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Not sure what the story is on this but kinda interesting.
Last year I picked up a 0320 a2b cheap to replace a tired 0290 and with a IA friend we thought we might rebuild it for around 10K...well I have a rebuilt in my cub for 25K.. we basically salvaged only the case and everything in the little lyc is new.
Steve
 
Back out to the airfield tomorrow to lengthen and calibrate the dipstick (using 5.5/6 litres of new oil) that came with the new oil filler tube I bought and have just wire locked in :)

I drained the oil out on Monday and 2 things:

1. It took absolutely AGES to slowly come out, in fact so slowly I was initially worried it had no oil left in it to come out!! But it had as much as the old dipstick had said, so PHEW!! It's got one of those "quick" oil drains, I guess "quick" from the angle of not taking the cowl off, but is slow oil flow a feature of these taps? One of the pins has come off the tap, I have it, but just wondering the best way to reattach it? It looks like they may have been originally soldered?

2. Although the oil is black black black!! I was reassured at how "oil-like" it was and felt quite thick, I was worried that black meant thin and not really working as oil!!

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Phil, It's a good idea to drain the oil right after flying when it is warmed up. Not only will it flow better but the contaminates will still be in suspension so will drain out rather than collecting in the bottom of the sump.
 
Phil, It's a good idea to drain the oil right after flying when it is warmed up. Not only will it flow better but the contaminates will still be in suspension so will drain out rather than collecting in the bottom of the sump.

Great idea and I'll do that next time, but I was worried about not much oil being left in the sump, so would have had to pour in a couple of litres, just to throw it away :) Really impressed with how the black stuff still felt like oil though :)
 
Don't worry about it. Fly it, drain it, walk away, come back the next day, close the drain and refill with new oil. If you let the contaminates settle in the bottom of the sump, they will still be there to make your new oil dirty sooner.

What oil do you use in the UK?
 
Don't worry about it. Fly it, drain it, walk away, come back the next day, close the drain and refill with new oil. If you let the contaminates settle in the bottom of the sump, they will still be there to make your new oil dirty sooner.

What oil do you use in the UK?

Thanks for this :)

Finished calibrating the new dipstick yesterday, at 1,2,3,4,5,5.5 and 6 and pre heated the oil to a more pourable consistency by floating the bottles in boiling water for a few minutes and poured straight in and settled to a level within 2-3 minutes!!

Using W/D100 grade oil

Took the bottom cowl off and cleaned the vast majority of the leaked oil off, ready for the test run/trip round the pattern during the week :) It LOOKS LIKE the worst (only?) leak may be coming from above the generator and starter, just behind the propeller flange? I’m going to check this thread, but I’m pretty sure someone suggested this place as a possible leak source :) Just checked and Skywagon suggested this, the crankshaft seal :) If it IS this, is it a MAJOR job to fix?!!

Also just ordered the 1.5” aluminium piano hinge to fabricate the new oil filler flap, which will basically be a long D shape, with the hinge on the straight edge

ALSO noticed a lot of burned black soot on the front of the starboard inside gear leg strut, right behind the exhaust.......... looks like burned oil residue!!!! You know my methods Dr Watson :)




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... It LOOKS LIKE the worst (only?) leak may be coming from above the generator and starter, just behind the propeller flange? I’m going to check this thread, but I’m pretty sure someone suggested this place as a possible leak source :) Just checked and Skywagon suggested this, the crankshaft seal :) If it IS this, is it a MAJOR job to fix?!!
Not difficult just awkward. You need to remove the propeller, nose cowl and ring gear for access. Your local mechanic should be able to help you with this.
 
Not difficult just awkward. You need to remove the propeller, nose cowl and ring gear for access. Your local mechanic should be able to help you with this.

Brill!!! Thanks! We’ve had the propeller and nose cowl off before, so it’s just the ring gear that’s uncharted territory :) Does it just unbolt and then fit a new seal?


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Brill!!! Thanks! We’ve had the propeller and nose cowl off before, so it’s just the ring gear that’s uncharted territory :) Does it just unbolt and then fit a new seal?


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I’ve just looked at the parts catalogue and although I’m a real engine newbie, it looks like this seal is internal and between the cases on the crankshaftIMG_0056.JPG? Or can it be fitted/replaced when the cases are still together?


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That is where it is except that it slides back from the crank flange into the opening and is installed with the crankcase already assembled.
 
That is where it is except that it slides back from the crank flange into the opening and is installed with the crankcase already assembled.

Let’s hope it’s just the seal and that the crank case hasn’t worn oversize!!! That service bulletin talks about complete engine disassembly if it has!!! 8(


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That is where it is except that it slides back from the crank flange into the opening and is installed with the crankcase already assembled.

Found a YouTube video showing this seal being fitted to an O540 - boinnnnggggggggggggg!!!!!

Is that special tool that curves around the prop flange essential?


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Is that special tool that curves around the prop flange essential?
It is not essential. However I have not done many one piece seals so I'll let others here give you the clues. The objective is to not damage the seal which could be easy if there is a nick on the flange.
 
It is not essential. However I have not done many one piece seals so I'll let others here give you the clues. The objective is to not damage the seal which could be easy if there is a nick on the flange.

I didn’t realise the seal was just a thick rubber ring with very elastic properties, until I saw the video today and now it’s obvious how it’s fitted :) You can probably see why I was wondering how on earth it could be fitted, before I saw it being stretched over the prop flange :)


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There have been seals replaced that continued leaking because there was a groove worn in the crankshaft by the previous seal lip. If you have such a groove you might stop the install of the new seal about an 1/8 inch from the bottom so the seal lip rides on a fresh surface. Another trick is to shorten the spring 1/4 to 1/2 an inch before reinstalling it in the seal before inserting the seal into the bore. Usually these tricks are done after multiple seal failures because the crankshaft seal area wasn't closely inspected for wear.
 
There have been seals replaced that continued leaking because there was a groove worn in the crankshaft by the previous seal lip. If you have such a groove you might stop the install of the new seal about an 1/8 inch from the bottom so the seal lip rides on a fresh surface. Another trick is to shorten the spring 1/4 to 1/2 an inch before reinstalling it in the seal before inserting the seal into the bore. Usually these tricks are done after multiple seal failures because the crankshaft seal area wasn't closely inspected for wear.

Thanks for this. Is it possible to “easily” inspect the area where the old seal has been? and if not easy, what’s the best way to do the inspection?

Do the replacement seals come with a spring? or is the existing one reused? Interestingly, I don’t see the spring listed in the parts list?


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