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Peteohms
12-03-2008, 04:10 PM
My Rotax 912 is an older engine from about 1991 and the oil reservoir does not have a drain plug on it. Would not do any good to have a drain plug since the reservoir practically sits on the engine and I'm sure I could not remove the plug without removing the engine.

It's a pain in the butt to remove the reservoir every time I change the oil. I'm thinking of getting a pump to suck the oil out. I know that there will be a small amount left in the tank so I thought every other oil change I would remove the reservoir.

Anyone else out there that does similar? Also do all of you purge the oil lines per Rotax recomendations after removing the reservoir?

DesertFox4
12-03-2008, 05:46 PM
Pete, I'd just as soon not have a drain on the bottom of my tank. I can't get to it anyway and just another place to leak.
I never remove my tank when changing oil on my Model 4. I do change right after a flight so the oil is mostly in the tank and very hot. I remove the top without disconnecting the big oil lines. Lay the top across the top of the engine on a drip towel and dip the hot oil out with a plastic juice can with the top cut off. You have to remove the screen of course and when you get the oil down enough remove the screen tray with a long needle nose pliers as it is very hot. I then wipe out the tank nice and clean. Usually there's a little lead residue in mine from burning 100 LL. I change filter each time also . I fill the new filter about half full of new oil and quickly spin it on before much spills. This helps pick up oil pressure just a little quicker on start up. Put the top on and fill with 3 quarts of oil. If I put any more than 3 quarts in it just blows it overboard . Very messy on the bottom of the airplane.
I never spin the prop during oil changes to get the last little drop of old oil out. Maybe because I don't try to get every drop of old oil out I haven't had to purge. I've never "purged" my engine yet with my routine and never had a problem. The newer model Kitfox has much more room under the cowling than we do and the tanks are mounted lower so removing the tank is much quicker. They also have screw on tanks fittings which is nice. Mine are the old hose clamp kind.
Others will respond with their procedures so we'll both learn something new I'm sure.:)

Peteohms
12-03-2008, 06:13 PM
Steve,

I hadn't thought about doing what you do but it makes sense. It will probably save some time. I just bought a pump from Harbor Freight so I can use it to remove the oil.

Pete

DesertFox4
12-03-2008, 06:39 PM
Pete, if your pump has plastic parts any you change oil when it's hot be careful that your pump doesn't melt and burn you. This has happened to others so be careful.

Peteohms
12-03-2008, 06:48 PM
I usually just warm up my engine slightly before changing oil but that is good to know.

Slyfox
12-05-2008, 08:58 AM
THis is how I change my oil. I think Rotax came out with a simular procedure.

First thing I do is take the new filter and set it on my tool box and fill it with new oil.
I warm the engine, than remove the top of the oil reservour.
Remove the screen.
Take a suck gun and suck out the oil, I take an old oil bottle and set it on top the engine and put the oil in that.
When I get down to the dohicky on the bottom I take that out and put it in the oil catch bucket on the floor with the screen.
I take a nice clean lint free rag and wipe out the oil reservour.
I put the dohicky back in and the screen, I don't clean them.
I fill the reservour with new oil to the level that it was when I removed the lid .
I put the top back on the reservour.
I check my filter on my box, in fact I check a couple times to make sure it's full of new oil.
I pull off the old filter.
I put on the new filter as soon as I get the old one off.
Now comes the easy part, I get in the airplane (put it outside)and keep the mags off and turn the engine over and watch the oil pressure. If it doesn't go up within 15 seconds, I stop and let the starter cool. Generally on the first try(about 10seconds) I have pressure. I still give it a rest and try again to make sure there is for sure pressure.
Than I turn on the mags and start her up, watching the oil pressure to make darn sure there is good pressure.
After a good warm up, I recheck the oil level and adjust as needed.

How long does this take, generally about 20 minutes.

I'v done this for the last 800hrs. I change my oil every 50hrs.

Big thing is, don't remove any lines, that can be a safety thing anyway, you could forget to tight them or just by removing lines you can cause trouble.

hope this helps.

RandyL
12-05-2008, 10:12 AM
Steve, good info. Are you running 100LL, and if so how much lead stuff are you finding in the bottom of the oil reservoir?

Slyfox
12-05-2008, 11:11 AM
The only time I use 100LL is when I'm out of town. When I do use it I use tcp. All other times I use auto gas, even with the alky. I have all auto hoses for fuel injection and both tanks are doing just fine. Right tank is 95 vintage with creme, there is a couple spots where the creme wore off from putting fuel in, still no problems. Left tank was a new one from 2005, skystar and no creme and doing just fine. Have never found lead in the tank oil tank.

Peteohms
12-05-2008, 06:43 PM
Thanks Steve for the detailed instruction. It should help simplify things for me.

Slyfox
12-06-2008, 09:26 AM
Steve, I've done the mags off ,turn starter and check for oil pressure also. Not everyone can do that part though if they don't have ignition switches set up like you and I do so I didn't mention it. Good point though.

It wouldn't be very hard to put in a couple switches for the mags. It sure is nice to be able to turn them off and start the engine. I put my RV7A that way as well.

darinh
12-08-2008, 01:47 PM
Don't know if any of you have been to the Rotax Owners site but they have some really good videos on subjects like this. In fact, they have one specifically on changing oil based on the Rotax service bulletins.

http://www.rotax-owner.com/

Over on the right-hand side click on the link for the Videos.

Another good bit of information is that purging is unnessesary unless you disconnect oil tubing on the suction side of the system. There is a Technical Article on the site that describes this much better than I can so if interested go ahead and read it.

Peteohms
12-08-2008, 03:33 PM
Steve^2 ( that's Steve Squared for 2 Steves),

I got the oil change done per your suggestions and yes I do have separate mag switches.

Darin,

I was aware of those videos but the oil change instruction does not apply since I have no drain plug and couldn't get to it if I did have one. The purging does apply, but I figure not if you just keep the hoses attached to the lid and just siphon out the old oil with the lid off. It is a messy process.

Thanks to all who commented.

darinh
12-08-2008, 03:54 PM
Pete,

Missed the part about not having the plug in the bottom...that definitely makes for a different set of circumstances. I have a quick drain plug in the bottom of my tank and when the engine oil is warm it drains out very nicely.

Slyfox
12-10-2008, 10:41 AM
No advantage, I measured the oil used when I pulled the lines versus sucking it out and leaving the oil in. It was only a couple table spoons of oil. So no you are just wearing yourself out. Not only that, you will have to blead the system, depending on how you do it. If you remove the oil return and do the prop turn over, I guess you can stop when the new out comes out. Here you also have a problem with a line being removed and having to make sure it is installed right so it doesn't pop off or leak in flight.

On my older 912ul engine, I also found that burping the system and than going right into oil change out, seems to get more oil out of the engine and return line. If I just run the engine and then changed the oil, the oil level was a little lower on the stick. I believe the last time I did it, I ended up burping the oil system after warm up.

One interesting thing on this, did you know you can burp the system by putting on the compression differential tester and doing a compression test, the last time I did it I heard the system burp, and was told this was normal. Expecially if you rocked the cylender and cause the rings to unseat. Maybe that was because my engine was getting weak, don't know.