Lyndon Posted December 9, 2015 Share Posted December 9, 2015 Gday . This is just an initial observation. I've pulled a couple of lifters and they are shot. I've had a quick look at the cam through the crankcase and it looks fine. This is contrary to what I should see. Rotax 912 with 1800 hrs. I have no experience with these engines. I'm hoping to get another 1000 hrs out it. Will it respond well with just lifters ???. I'm just freshening up the top end with new orings. Everything is clean and the engine looks perfect. Thanks Lyndon Link to comment Share on other sites More sharing options...
facthunter Posted December 9, 2015 Share Posted December 9, 2015 One of the reasons to cut open the filter at each oil change is to pick this sort of thing up. Metal through your engine can damage it. Hopefully the filter got the lot. I presume the face contacting the cam is your concern. This is a highly loaded area. Has the correct oil always been used? Sit down when you get the price. Nev Link to comment Share on other sites More sharing options...
Lyndon Posted December 9, 2015 Author Share Posted December 9, 2015 It has had the correct oil. But I'm my opinion its not up to scratch. Porsche have a similar problem and it's the oil. What is good for the cat and emissions is not good for their valve train. Anyway when I say they are shot I mean the case hardening is just on the way out. Eg you would never put them back in. My concern is the cam looks good but lifters don't. Thanks Lyndon Link to comment Share on other sites More sharing options...
geoffreywh Posted December 12, 2015 Share Posted December 12, 2015 Er?................Rotax 912 80hp?............... I thought that they had a life of 1800hrs?.................quote: "This is contrary to what I should see".......I think that this exactly what you would expect to see.... Link to comment Share on other sites More sharing options...
Lyndon Posted December 12, 2015 Author Share Posted December 12, 2015 100 hp. They have a tbo off 2000 hrs. Nothing to do with how long they last. Sorry I should have explained myself better. Cam looks good and lifters are worn. One would expect both the same. I was hoping to get some advice from someone who knows this engine. I have since found out that new lifters will be fine. Apparently they do fail but at early hours. At the hrs this engine has done it's just wear. Apart from the oil rings and lifters the rest of what I can see will easily do it again. Thanks Lyndon Link to comment Share on other sites More sharing options...
facthunter Posted December 12, 2015 Share Posted December 12, 2015 Wear is when abrasive particles remove metal. Usually a slow process. Pitting can be corrosion or surface fatigue due high repetitive loads or incorrect material/ heat treatment. Nothing lasts forever. Roller bearings have predictable "life" based on load and cycles and speed. However you change the oil it won't make them last forever. A bigger bearing would last longer but it all adds weight/bulk. Nev Link to comment Share on other sites More sharing options...
Downunder Posted December 12, 2015 Share Posted December 12, 2015 Pre 2006 with the older crank case style do not have 2000 tbo I believe. Link to comment Share on other sites More sharing options...
Ultralights Posted December 12, 2015 Share Posted December 12, 2015 running Avgas without the recommended 25 hr filter and oil change will cause excessive wear in the cam system, as the lead paste trapped in the oil doesnt help with the lubricating properties of the oil.. after a while with avgas use, you will get a silvery look to the oil, and eventually it will go a light grey colour, this is bad.. i have seen a 912ULS camshaft crack in half due to the oil galleries that lubricate that area clog up with lead residue paste, but the oil was a very grey colour and hadnt been changed for a while. 2 Link to comment Share on other sites More sharing options...
Lyndon Posted December 27, 2015 Author Share Posted December 27, 2015 I have had time to clean and measure it. Been busy with a race engine that has ruined 4 k worth of titanium valves and the head as well at another 3 k. The joys of motor cyles Surprisingly the rings are well worn and the bore has zero wear. The bore fair enough but the rings were well shot before 1740 hrs. The guides are perfect so I'm thinking the shitty k and n filters did ok and dirt did not wear them. One thing I can't work out. Why sweat a fitting into a housing that runs a nice o ring. Only to leak where it's been sweated. Why not have an o ring and and collar. Cheaper and it actually seals. All my water outlets have leaked coolant. Yes I know glycol finds every weep but its unacceptable and such a easy fix. So I have something in mind. If it works I Will share it. Ps the bores wernt touched. My opinion is anything done to it will not be as good as leaving it. A good clean and she will be fine. Lyndon Link to comment Share on other sites More sharing options...
Downunder Posted December 27, 2015 Share Posted December 27, 2015 The coolant elbows are screwed in. They need to be loctited to seal. Different engine instslations have them pointing in different directions for the hoses. The loctite holds them in the required direction and seals them. I don't think it's particularly ideal also. Pull on an elbow, crack the loctite and it leaks. Link to comment Share on other sites More sharing options...
Lyndon Posted December 27, 2015 Author Share Posted December 27, 2015 I have coolant elbows bolted with an o ring. But the design is these are sweated where it leaks. Lyndon Link to comment Share on other sites More sharing options...
planesmaker Posted December 27, 2015 Share Posted December 27, 2015 Lyndon yes bolted with o ring but screwed with loctite into bolted collar. Not sweated at all if it is standard rotax. Easy fix 1 Link to comment Share on other sites More sharing options...
Lyndon Posted December 27, 2015 Author Share Posted December 27, 2015 That is good news. Will have a crack at redoing then them. Lyndon Link to comment Share on other sites More sharing options...
Downunder Posted December 27, 2015 Share Posted December 27, 2015 Yeah, I thought sweated/pressed in to, but they are screwed. Some sort of fine parallel thread. A mate come to me saying he replaced the o ting several times but it still leaked..... soon worked it out. 1 Link to comment Share on other sites More sharing options...
Lyndon Posted December 27, 2015 Author Share Posted December 27, 2015 So I'm guessing heat and unscrew it. Link to comment Share on other sites More sharing options...
Downunder Posted December 28, 2015 Share Posted December 28, 2015 So I'm guessing heat and unscrew it. Yeah, doesn't take much heat. Thorough clean/degrease..... the usual. Just be careful when fitting the hose and clamp not to pull on it too hard. Loctite 648 or 243 are recommended............ Link to comment Share on other sites More sharing options...
cscotthendry Posted December 28, 2015 Share Posted December 28, 2015 So I'm guessing heat and unscrew it. The best way is to use a heat gun rather than a torch. The same applies to the pipes coming out of the water pump. The pipes are very soft aluminium so be very gentle with them. However, if you damage one, they're not terribly expensive to replace ... Link to comment Share on other sites More sharing options...
Blueadventures Posted December 28, 2015 Share Posted December 28, 2015 I have had time to clean and measure it. Been busy with a race engine that has ruined 4 k worth of titanium valves and the head as well at another 3 k. The joys of motor cyles Surprisingly the rings are well worn and the bore has zero wear. The bore fair enough but the rings were well shot before 1740 hrs. The guides are perfect so I'm thinking the shitty k and n filters did ok and dirt did not wear them. One thing I can't work out. Why sweat a fitting into a housing that runs a nice o ring. Only to leak where it's been sweated. Why not have an o ring and and collar. Cheaper and it actually seals. All my water outlets have leaked coolant. Yes I know glycol finds every weep but its unacceptable and such a easy fix. So I have something in mind. If it works I Will share it. Ps the bores wernt touched. My opinion is anything done to it will not be as good as leaving it. A good clean and she will be fine.Lyndon There is a video about how to do this on the rotax owner.com forum. Worth a read. Cheers Mike Link to comment Share on other sites More sharing options...
Lyndon Posted December 28, 2015 Author Share Posted December 28, 2015 All I can find is house stuff. Lyndon Link to comment Share on other sites More sharing options...
Blueadventures Posted December 28, 2015 Share Posted December 28, 2015 All I can find is house stuff.Lyndon Hi L Not sure if your last post was a reply to mine? Here is the link about coolant elbows http://www.rotax-owner.com/en/videos-topmenu/rotax-minute/375-elbow I joined the forum years ago; great value for the money (about $35 per year). Cheers Mike Link to comment Share on other sites More sharing options...
Guest nunans Posted February 17, 2016 Share Posted February 17, 2016 Gday lyndon, how did you go with your engine? Did you do the rings? IT sounds to me like you know your stuff so I'm wondering if I might be able to pick your brains, I have the same engine as you but mine has more hours, When I bought it I found 1 soft cylinder, checked leak down and got inlet valve leak. I assumed previous avgas use so i pulled all 8 valves cleaned and lapped thought I fixed it but after less than 50 more hours the same inlet valve is leaking again... any ideas? Link to comment Share on other sites More sharing options...
Lyndon Posted February 17, 2016 Author Share Posted February 17, 2016 Yes I'm replacing my rings. My motor has 1740 hrs on it. The heads are like new. I lapped my valves but ever so light. Seats and valves have ton left on them. If you blued them and had a good seat with a good valve I can't see why it would be leaking. Maybe pull that head and get it looked at. I don't know your level of expertise but if you take it somewhere be careful. Everyone is an expert. You can cut the Seats but not the valves. Are you in SA . Lyndon 1 Link to comment Share on other sites More sharing options...
Lyndon Posted February 17, 2016 Author Share Posted February 17, 2016 Update. I have split the cases and had the cam and lifters reground. I wasn't happy with new lifters on an old cam. The cam is nitraded. So hard as cats head for probably 2 thou then it's cheese which would explain some failures and why they go suddenly.they did give me the numbers but it's good now and should do another 1740 hrs with a better oil in it. Heads passed the softness test with flying colors. Link to comment Share on other sites More sharing options...
JimG Posted February 18, 2016 Share Posted February 18, 2016 Hi Lyndon , can you tell me where you had the camshaft and lifters reground. cheers JimG Link to comment Share on other sites More sharing options...
Lyndon Posted February 18, 2016 Author Share Posted February 18, 2016 Ivan Teigh cams in Brisbane. I've spelt it wrong but Google will grab it. Speak to Dean. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now