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Oil tank

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Gtblu

Joined: 18 Jul 2006
Posts: 37
Location: Australia

Posted: Sat Oct 06, 2012 9:47 pm Post subject: Oil tank

Hi All,



I have a 912 uls that has cracked the 1000 hours, and have noticed a change in the way the oil lies in the scavenger tank. An oil check after shut down  registers the level well below the lower limit marker. If I hand turn the prop (40 turns ) the oil level will come back up, although I don't seem to be able to get it to "gurgle" anymore. If it is left without starting up after winding the oil out of the tank by hand turning prop, it will stay at that level till next flight. Oil pressure seems to be the same, about 2.5 indicated, and still is up at 4 at startup, so that seems fine. Logically it suggests the scavenger system is not operating satisfactorily, but I don't know how it works. Question is has anyone had this issue, and is it serious!



cheers



Geoff Bell

klinefelter.kevin(at)gmai
Guest

Posted: Sun Oct 07, 2012 3:42 am Post subject: Oil tank

Have you opened up the tank for an inspection?



On Oct 6, 2012, at 10:47 PM, "Gtblu" <gtbjbell(at)gmail.com> wrote:



 	  Quote: 	
		   

 

 Hi All,

 

 I have a 912 uls that has cracked the 1000 hours, and have noticed a change in the way the oil lies in the scavenger tank. An oil check after shut down  registers the level well below the lower limit marker. If I hand turn the prop (40 turns ) the oil level will come back up, although I don't seem to be able to get it to "gurgle" anymore. If it is left without starting up after winding the oil out of the tank by hand turning prop, it will stay at that level till next flight. Oil pressure seems to be the same, about 2.5 indicated, and still is up at 4 at startup, so that seems fine. Logically it suggests the scavenger system is not operating satisfactorily, but I don't know how it works. Question is has anyone had this issue, and is it serious!

 

 cheers

 

 Geoff Bell

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=384824#384824

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Sun Oct 07, 2012 4:12 am Post subject: Re: Oil tank

Geoff,



Your experience is in the normal range. 



The 912-F3 in the Katana I fly has 1100+ hours. On this engine, it takes from 40-50 compression strokes to get the "gurgle". 2.5 bar oil pressure after warm up is about what I see (~38-40 psi) when warm and about 60-70 psi when first starting.



The "scavenging system" is merely air pressure in the crankcase that pushes the oil in the bottom of the crankcase back to the oil tank (dry sump). The air pressure is generated by engine compression, i.e., blow by gases that leak past the piston rings.

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

Duncan McFadyean

Joined: 18 Jan 2011
Posts: 219

Posted: Sun Oct 07, 2012 4:13 am Post subject: Oil tank

Or checked the crankcase for cracks?

--

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Sun Oct 07, 2012 6:22 am Post subject: Re: Oil tank

Hi Geoff,



I'm with Thom. Yours is within perfectly normal operations. Each engine is slightly different like an individual. I see engines all the time that take one or two turns to get oil back and some 40 turns. The amount of oil that stays in the bottom of the crankcase differs also and that is usually what dictates how many turns a prop takes to get the gurgle. Some engines keep the oil high up on the stick (less oi in the crankcase) and some low with more oil being back in the crankcase. It is all normal. So long as the right amount of oil is in the engine then it would be considered normal. People who say it takes a lot of prop turns to get a gurgle tend to have more oil in the crankcase than the guy that gets the gurgle in a few turns. If you haven't sprung a leak with oil all over everything and oil pressure is good then, No worries.

Depending on your engine TBO 1500 verses 2000 and 100LL usage you may have a gearbox inspection due. It is either at 600 hrs or 1000 hrs.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

BARRY CHECK 6

Joined: 15 Mar 2011
Posts: 738

Posted: Sun Oct 07, 2012 7:40 am Post subject: Oil tank

Roger:



So you are saying; The fellow who gets gurgle in say 10 flops of the prop has less oil in the crank case than the fellow who takes 40 flops of the prop...  But if there is a oil quantity difference why are there "No worries"?  Shouldn't there be a standard so both fellow have the correct amount of oil (same amount of oil)...  Say: Always do 40 flops even if the gurgle happens at 10?  This way the fellow with 40 KNOWS he has oil and the fellow with 10 is not hopping and praying or playing Russian Roulette.

 



Another question is: What happens to the oil quantity when the engine is running, do both the 10 flop and 40 flop oil quantities in the gearbox equal out?

Barry



 On Sun, Oct 7, 2012 at 10:22 AM, Roger Lee <ssadiver1(at)yahoo.com (ssadiver1(at)yahoo.com)> wrote:

[quote] --> RotaxEngines-List message posted by: "Roger Lee" <ssadiver1(at)yahoo.com (ssadiver1(at)yahoo.com)>

 

 Hi Geoff,

 

 I'm with Thom. Yours is within perfectly normal operations. Each engine is slightly different like an individual. I see engines all the time that take one or two turns to get oil back and some 40 turns. The amount of oil that stays in the bottom of the crankcase differs also and that is usually what dictates how many turns a prop takes to get the gurgle. Some engines keep the oil high up on the stick (less oi in the crankcase) and some low with more oil being back in the crankcase. It is all normal. So long as the right amount of oil is in the engine then it would be considered normal. People who say it takes a lot of prop turns to get a gurgle tend to have more oil in the crankcase than the guy that gets the gurgle in a few turns. No worries.

  

 

 Depending on your engine TBO 1500 verses 2000 and 100LL usage you may have a gearbox inspection due. It is either at 600 hrs or 1000 hrs.

 

 --------

 Roger Lee

 Tucson, Az.

 Light Sport Repairman - Maintenance Rated

 Rotax Repair Center - Heavy Maint. Rated

 Home [url=tel:520-574-1080]520-574-1080[/url]  TRY HOME FIRST

 Cell [url=tel:520-349-7056]520-349-7056[/url]

 

 

 

 

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 http://forums.matronics.com/viewtopic.php?p=384839#384839

 

 

 

 

 

 

 

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Alan Carter

Joined: 02 Jul 2012
Posts: 378
Location: Kent, England.

Posted: Sun Oct 07, 2012 10:58 am Post subject: Re: Oil tank

Hi All.

I am have trouble with oil level all so.

I came back from a 3 hour flight the other day an noticed the following day oil a pool of oil by the nose wheel, and it was all down the underside of the fuselage, After inspection no leaks, but oil level was well above the dip sticks maximum level.

So i cleaned all the oil off with paper towels, and with a small tube sucked out the oil in the reservoir to the correct level, then gurgled about 25 blade pulls, and sucked some more oil off.

This is why i posted the question "Can coolant get into the oil system" Ans, only in very rare cases via the water pump.

As a few days earlier i had topped up the waterless coolant to about 1" below Max, having removed the cowling i rechecked this to my relief it was at the same level.

However i flew today and after the flight the oil was well above the max mark agian.

So sucked some more out.

Now unless i am making oil, or something is getting mixing with it, the only thing i can think of is i must have overfilled it,

And some how the Gurgling may not be getting all the oil out of the crankcase so i am not getting a true reading??

Oil temp in flight 82c and press 4.3 bars.

I am still puzzled, see what happen next time

Alan

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Sun Oct 07, 2012 11:03 am Post subject: Re: Oil tank

The oil that accumulates in the bottom of the crankcase is mostly the oil that drains/sprays down from the lubricated parts after doing its job at those locations. It also comes directly from the pressure relief valve when it is open. 



One of the factors that affects how long it takes to burp the oil tank is how high (vertically displaced) the tank is above the crankcase bottom. The installation manual shows a permitted range. If the tank is mounted relatively high in this range, then it will likely take more prop turns to get the burp than if it is mounted relatively lower. This is only one of the factors but one that does make a difference. 



How many prop turns it takes to burp the engine in no way affects the lubrication system's function as long as the pump is getting its required oil supply, the correct quantity of the oil is in the system and all elements are within service limits and functioning normally. 



The only purpose of doing the burp process is to determine if the oil quantity is correct, between min and max with all crankcase oil returned to tank. In practice, I check the oil dipstick before flight (before burping). If the oil is at the minimum or a bit higher, I don't bother burping since I know the actual quantity of oil is greater than that. If it shows below the minimum mark, I do the burp to make sure there is sufficient oil to run the engine safely.

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

Gtblu

Joined: 18 Jul 2006
Posts: 37
Location: Australia

Posted: Sun Oct 07, 2012 1:44 pm Post subject: Re: Oil tank

The great thing about living on the darkside of the world is when I post a question in our time, I wake to all this sea of knowledge, thanks again for your replies. 

Thom.. no sign of oil anywhere on the underside of the engine or the cement floor. I have been watching a 'shine' of oil on the cooler, but it doesn't seem to be an issue, and was probably a drip or two from a filter change. I also dug out the manual to see how oil was pumped back. I thought it was pressure, but couldn't remember how. Has your Katana always been like this, or has it changed?



Kevin.. just changed the oil, which for me is removing the oil tank and dismantling and cleaning.



Roger, what is of concern for me is that something has changed. It used to gurgle after about 3 complete revolutions ( Barry; is that one flop or three with a three bladed prop?). Now it takes a sore arm number of turns to bring the oil up and no gurgle! I fly less frequently than a year ago if that is a factor, but I don't see why. And the oil level pre flops is way below minimum mark, say half again of the min max range.



Thanks Roger for gearbox tip, it has been serviced twice in its life chasing a vibration . A new prop took away the vibration, ( and inserting  bolts that didn't run out of thread!) however, there seems to be a bit of vibration again  I think when the crank shaft 'floats' between bearings at about 3000 revs, on final. Still working on that one. But it also may be a factor.



Thanks again for replies.



cheers

Geoff Bell

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Sun Oct 07, 2012 3:01 pm Post subject: Re: Oil tank

Hi Guys,



Again I agree with Thom.



Oil back in the crankcase can be different between engines because of different oil tank heights compared to the engine. It may be a little too high, right in the middle or mounted a little too low. The oil filter will play a part depending on how much it may leak back oil because of the anti drain back membrane not doing a good job and again the height of the oil tank plays a big part. You may have an old style filter verses new. There are many things that will affect this. Over filling can happen even at an oil change and you only add three quarts. If you fail to turn the prop over and gurgle it first before draining some planes keep back enough oil in the crankcase to end up over filled after you change the oil and then it spits or drains out the oil vent tube on the neck of the oil tank. Never turn a prop when the oil tank is empty or the filter is off or you will inject air and trash a lifter. If air is introduced you need to do an oil purge as described by Rotax. The oil is returned back to the oil tank by crankcase pressure which is only 4-5 psi. Rotating the prop builds this pressure and causes the oil to be pushed back to the oil tank. The return line is the one on the bottom of your engine.



Hi Geoff,



I hope when you remove the tank you plug up the oil lines and don't let them drain. If you let them drain and install a dry oil filter then you are pumping air into the system unless you do an oil purge each time. Even if you don't kill it in one start it may slowly kill it and then you may see changes or end up doing a full overhaul early. 



Felt vibration in the 3000-4500 range can be one of four things. Poor carb sync, low slipper clutch friction torque, prop blades not all equal or you need to do a dynamic prop balance.

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

Gtblu

Joined: 18 Jul 2006
Posts: 37
Location: Australia

Posted: Sun Oct 07, 2012 3:56 pm Post subject: Re: Oil tank

Hi Roger,



Yes , very cautious about air in the lines! One thing I do is take all the spark plugs off so there is no compression when I change the oil and a half filled filter,  and repurge the lines by cranking with the starter motor until oil pressure comes up, then replace new plugs. I have done that every 25 to 30 hours divided by 1000 hours so 30 times. Do you think that is foolhardy? 



I think that I have the new style filter on this time, ordered direct from Rotax importer



And I hadn't thought of slipper clutch, will test today.



I also see the oil cooler may have a slight leak this morning, as there is a oil shine on the outside again today after cleaning yesterday. 



Thanks for feedback.



regards



Geoff

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Sun Oct 07, 2012 5:00 pm Post subject: Re: Oil tank

Geoff,

Perhaps I misunderstood you and you already know this. In case you don't... You must have the spark plugs installed to get compression to get oil to return to the tank. Without the spark plugs installed you can spin the prop until the cows come home and the oil in the crankcase will not return to the tank.

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

Gtblu

Joined: 18 Jul 2006
Posts: 37
Location: Australia

Posted: Sun Oct 07, 2012 5:19 pm Post subject: Re: Oil tank

aha.. good point Thom. I only do this to purge lines up to crankcase. Good point for checking oil level however!



cheers



Geoff

Gtblu

Joined: 18 Jul 2006
Posts: 37
Location: Australia

Posted: Mon Oct 08, 2012 2:27 am Post subject: Re: Oil tank

Hi All, 

I was hand turning the prop to try and get a gurgle, and was up to 120 revolutions of the prop when it struck me that the line back to the tank must be blocked. Well it was, but by the obscure method of the overflow pipe being kinked, thus causing a build up of pressure I imagine in the scavenger tank and thus stopping oil coming back into it. Continuous flying in that configuration may have become interesting!



Thanks for all the suggestions, number 1 lesson again is to follow a hunch or a change in character till your satisfied its OK.



Still haven't followed up the vibration.. That's next.



cheers

Geoff.

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