Ayecapt Posted January 16, 2016 Share Posted January 16, 2016 Hi yes a 912s engine ( ex ga) the engine is tight at top dead centre ( tdc ) and bottom dead centre ( bdc ) with the plugs out and gearbox removed. There is also very high copper showing up in the oil filter and in the oil sample analysis. Doing a crank angle test today . But was wondering if anyone has heard of this fault before. It seems Rotax hasnt . Remarkably the engine was / is performing well starts first kick developing smooth reliable power . Oil , coolant temps normal , oil pressure normal . No rattles or odd noises at all. Just the tightness and the copper. Engine TTSN is 1300 hrs . Gearbox has 200 hrs TTSO and basic tests are ok . It could be that the copper and tightness are 2 separate issues and not related. Of course its grounded till we find the cause. Link to comment Share on other sites More sharing options...
rankamateur Posted January 16, 2016 Share Posted January 16, 2016 Foxbat trainer at Glen Innes rings a bell. Think it was a bent crankshaft but I wasn't involved with it. Link to comment Share on other sites More sharing options...
Ayecapt Posted January 17, 2016 Author Share Posted January 17, 2016 Thanks. Spent today with our L2 and got to bottom of the prob . Without going and pointing fingers..... A previous owner performed a top end overhaul of the engine. Rings valves and rocker bushes. They replaced the rocker bushes with brass not bronze and NOT the rotax plastic ones that should have been fitted. Result was 7 out of 8 bushes are worn to a oval shape. And they were binding as the valves were lifting . Most tight at top dead centre. So it will be quite a parts bill , bushes , rocker shafts , new lifters because there will be brass in them and possibly rings due to brass in the oil . you can see a brassy tinge in the cylinder walls. Thanks Brian 1 3 Link to comment Share on other sites More sharing options...
crashley Posted January 17, 2016 Share Posted January 17, 2016 thanks for the update always it is good to find the cause of a problem now a bit of work, a few dollars then ready for another couple of thousand hours Link to comment Share on other sites More sharing options...
Guest asmol Posted January 17, 2016 Share Posted January 17, 2016 You say it was ex GA so it must have been maintained to GA standards. They cant substitute parts without CASA approval or an STC on in the case of LSA the LOA from what i have read. I would be asking for a "please explain" from the previous owner along with compensation to bring the plane back to airworthiness standards. Link to comment Share on other sites More sharing options...
Lyndon Posted January 23, 2016 Share Posted January 23, 2016 Why would the lifters need replacement ??? Lyndon 1 Link to comment Share on other sites More sharing options...
Lyndon Posted January 23, 2016 Share Posted January 23, 2016 Also don't don't touch the barrels until your happy with what your going to do. There are many schools of thought 're them. Personally a clean rag and carby clean then a rag and oil. Lyndon Link to comment Share on other sites More sharing options...
Ayecapt Posted January 23, 2016 Author Share Posted January 23, 2016 Hi all and thanks for the comments. The mods were we believe, ( being careful here ) authorised by a person outside the GA arena. And after registered in RAAUS. Doesnt make it less stupid. The lifters are being done for 2 reasons the first is that one was noted to be leaking and secondly the brass will have made its way into the lifters and might cause future issues. Thes brass entered the oil just after the filter exit so it has been carried just about everywhere. Cleaning the oil cooler of brass could be difficult . So the parts required might yet get bigger. We decided to get our local L2 to carry out the repairs . He is very experienced with the 912 series engines. If folks are interested i will do a weekly update ? Heres a photo of the swatch of oil filter showing the brass in it and one of the offending rocker bushes. Note its out of round . 2 Link to comment Share on other sites More sharing options...
Guest asmol Posted January 23, 2016 Share Posted January 23, 2016 Watching Gold Rush Alaska earlier, now, if that brass was gold in the ripples you would be on a winner but unfortunately its not gold. Looks like a total rebuild i am sorry to say. At least it didn't fail in the air ! Link to comment Share on other sites More sharing options...
facthunter Posted January 24, 2016 Share Posted January 24, 2016 The main and big end bearings will have to be considered and inspected also. They are a built up crank. I would have that done at the factory. Nev 1 Link to comment Share on other sites More sharing options...
Lyndon Posted January 24, 2016 Share Posted January 24, 2016 Wouldn't the filter have caught it all. The rockers would get clean oil. Then after them its full of shit then it goes no where and back thru th filter. Why would the plastic bushes fail????. Is what I would be asking. Then why would anyone not put the correct part back in. That makes no sense at all. I'm guessing the plastic bushes would be cheap as and in stock. My motor is apart and at 1740 hrs the bushes are perfect. If you are doing a full rebuild you would want to your sums before you commit to it. In 2 mins the oil pump is off. If that is fine then I would say everything else is fine as well. Lyndon Link to comment Share on other sites More sharing options...
facthunter Posted January 24, 2016 Share Posted January 24, 2016 I have seen a BMW six engine ruined by the steel from the rocker bushes going all through the motor. The filter in theory should have stopped it . The engine would not hold tappet clearances was the only symptom. It ran hard steel on hard steel. It happened over a period of time though. Nev Link to comment Share on other sites More sharing options...
Downunder Posted January 24, 2016 Share Posted January 24, 2016 When the filter is blocked the internal filter bypass valve opens. This allows unfiltered oil through. So the filter element can be 100% blocked but the engine will still receive oil. Quite possibly cold oil, due to higher viscosity, may also move unfiltered through the bypass valve until adequate temp/viscosity has been reached. http://www.recreationalflying.com/threads/rotax-912-914-oil-filter-strip.121892/ Some people consider a situation with metal contaminated oil circulated through the engine "unrecoverable" and it's only good for spare parts. Anyway, I guess you have quite a few oil changes coming up. Good luck. 2 Link to comment Share on other sites More sharing options...
Lyndon Posted January 24, 2016 Share Posted January 24, 2016 I've seen many failures in late model bikes. Catastrophic gear box and roller bearing failures etc. Most if not all once the engine is pulled apart and the pump found to be ok they are just cleaned the failed part replaced and are just fine. Pressing the crank apart to see if the filter didn't work seems over the top. You can pull plenty of stuff apart to check for wear that is easy to access. If it doesn't look new at those hrs then you may consider shit it the oil has done it and I'm thinking it would be uneconomical to repair. But why would a valve train wear. Excessive load on it may wear the bushings. Tight guide or incorrect valve springs ????. I would be having good look at the cam as well. They are nitraded so at a guess maybe two thousand of an inch deep and then it's cheese. The lifters have at least 2mm of hardening on them. If these are fine then I don't think you have much of an issue. Lyndon Link to comment Share on other sites More sharing options...
Downunder Posted January 24, 2016 Share Posted January 24, 2016 They are hydraulic lifters. He's worried they are full of brass...... Link to comment Share on other sites More sharing options...
Lyndon Posted January 24, 2016 Share Posted January 24, 2016 A filter that full that it bypasses. Wow. If that were the case the shit in oil would lunch that engine in no time. It would be very easy to see once it's apart. Probably not even good for parts Link to comment Share on other sites More sharing options...
Downunder Posted January 24, 2016 Share Posted January 24, 2016 I guess Rotax see it as better to have contaminated oil flowing than no oil at all. I can understand their reasoning. 1 Link to comment Share on other sites More sharing options...
Lyndon Posted January 24, 2016 Share Posted January 24, 2016 If the oil has gone thru the filter it will be fine. What can fit thru a filter will fit thru the engine without a problem. That's how it's designed. It's deemed small enough. Otherwise they would change the micron filter ing in the filter Link to comment Share on other sites More sharing options...
Lyndon Posted January 24, 2016 Share Posted January 24, 2016 The filter is not designed for that. It's for cold climate s and thick oil. It would not happen here. A rebuild with silicon for example. Minus 20 start up with a 60 weight racing oil in a Porsche. Then yes worming can be an issue. Block galleries and even when the filter is working again in say 60 seconds. It's to late. That engine will fail as it has blocked galleries. In Australia with a say a 40 or 50 oil it's never going to bypass. Link to comment Share on other sites More sharing options...
Lyndon Posted January 24, 2016 Share Posted January 24, 2016 I still can't get over someone putting a bronze Bush in there. It would have to be a case of loosing an original part. In a rush . We can't wait and 10 minutes later on a lathe we have all new bushes. Don't worry I've seen this stuff in engines before they would have said. Rotax put the plastic bush in there for a reason I'm sure. The consequences of it could have been dire. In a way your very lucky Link to comment Share on other sites More sharing options...
Ayecapt Posted January 24, 2016 Author Share Posted January 24, 2016 The brass bushes should never ever have been maunufactured and installed ....the brass is too soft in this application. The plastic has a hardness greater than this brass. In effect this has probably saved this engine. Our lab tests of the oil showed copper , extreemly high, zink high and some lead which we can explain. ( av gas on occasions). But we have no steel or other metals related to case hardened bearings , cams or rocker shafts. We have no metals showing in lab report that relates to big end bearing metals. Or aluminium . So all thats been worn is brass. But the fine bits of brass will have entered the hyd lifters. There could be some in the oil galleries , and the oil cooler will have heaps , might need a new one but we have sent it to a company that specialises in internal cleaning of oil coolers ( usually in mining equipent ) they will catch what comes out at each cleaning cycle. We caught this problem early. Although the filter shows a lot of brass the one before showed just a trace so we immediatly saw the trend . The engine was actually running perfectly. Was not using abnormal amounts of oil A credit to its designers. The labs interpretation of the oil samples was invaluable . Yes prob do a 5 hour filter inspection , and send oil to the lab . Then decide on the oil change period when these results come back. On the oil flow the rockers are straight after the filter , so any brass went right through the engine but some did settle in the oil can . Cheers Brian 2 Link to comment Share on other sites More sharing options...
Lyndon Posted January 24, 2016 Share Posted January 24, 2016 How can the be. Oil to rockers come up the push rod. After that it goes no we're. It goes back thur the filter Link to comment Share on other sites More sharing options...
Lyndon Posted January 24, 2016 Share Posted January 24, 2016 How does brass get pass your filter ??? Link to comment Share on other sites More sharing options...
Lyndon Posted January 24, 2016 Share Posted January 24, 2016 The more a filter gets shit in it the better it filters. Thus your oil pressure increases. So in fact it's filtering better than a new one Link to comment Share on other sites More sharing options...
Lyndon Posted January 24, 2016 Share Posted January 24, 2016 I would be interested if you could ask the oil experts where the zinc is from and what oil was run in it. A flat tappet cam like your Rotax likes about 1300 ppm which is a challenge to find in today's oils. Link to comment Share on other sites More sharing options...
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