914 Stuck Waste Gate Lessons Learned

[DavidOber]

So after this happening to me twice, here is the plan after consulting with my mechanic:

 - Use mogas whenever possible
 - If avgas is used - add decalin
 - Let the engine stay into boost for 5 minutes
 - Allow the engine to cool down for 5 minutes after full stop
 - Apply mouse milk to the waste gate (weep hold and bottom shaft) once a month
 - Switch to Mobil 1 4T synthetic oil

I will let you guys know how this works out.

David

[Flocker]

Sept 5, 2019 15:01:09 GMT DavidOber said:

So after this happening to me twice, here is the plan after consulting with my mechanic:

 - Switch to Mobil 1 4T synthetic oil

Rotax approved this?

[Glenn]

Sept 5, 2019 15:01:09 GMT DavidOber said:

So after this happening to me twice, here is the plan after consulting with my mechanic:

 - Use mogas whenever possible
 - If avgas is used - add decalin
 - Let the engine stay into boost for 5 minutes
 - Allow the engine to cool down for 5 minutes after full stop
 - Apply mouse milk to the waste gate (weep hold and bottom shaft) once a month
 - Switch to Mobil 1 4T synthetic oil

My guess is your mechanic has not gone to an approved Rotax service course.

[DavidOber]

My mechanic is your mechanic..lol. He said he got the direction from Lockwood. I have read many discussions on various forums...seems like both oils are being used in rotax engines.

[Glenn]

Oops, I stand corrected!!  Same mechanic?  LOL  I just maintain my Rotax but Nathan does lots of Rotax work.  Nathan and Scott do good job and you and I don't have to fly for hours to get there.   I was not familiar with Mobil 1 4T so I looked it up.  It's for 4 cycle high performance motorcyle engines and is API SN.  Since Mobil 1 4T is API SN and that exceeds the Rotax requirement of API SG, then it seems using it does not conflict with Rotax guidance.  That must be the reason Lockwood said you're OK to use it. I was trained at Lockwood and they know their stuff.

"Specifications from SA to SH are considered obsolete, meaning that you cannot get any official license from the API. It is meant for 1995 and older engines. As explained earlier, the higher the letter, the more recent and a higher specification would supersede the lower ones. API SN to SJ are for the most recent cars, API SH to SA for the older cars. For example, if we have an oil with specification SN, it can also be used for vehicles which request API SM, SL and SJ; it is backward compatible."


Glenn

[Cluemeister]

I think your main culprit is 100LL.

[DavidOber]

While I agree not much I can do until airports sell mogas. I would say my mix is 70-30 mogas to 100LL. I put mogas in at the home airport...but when traveling no choice.

[MarkGregor]

Ask your service Tech if the wastegate was sticking from the lead or carbon buildup. We usually see carbon buildup causing it even when the plane runs on LL.

[Ed Midgley]

This might seem a little strong but, Shell Sport 4 can’t take the turbo’s heat and cokes up and blocks the scavenge line.
Two months ago I had to make a dead stick landing from 8000’ when my turbo pumped all but 6oz of my oil through the turbo exhaust.
The only oil I’ll ever use again is Mobil 1 4T. If I have to use Avgas I’ll use Decalin and change the oil often.
Ed

[Cluemeister]

YIKES!

[buzz]

Sept 6, 2019 12:32:30 GMT Ed Midgley said:

This might seem a little strong but, Shell Sport 4 can’t take the turbo’s heat and cokes up and blocks the scavenge line.
Two months ago I had to make a dead stick landing from 8000’ when my turbo pumped all but 6oz of my oil through the turbo exhaust.
The only oil I’ll ever use again is Mobil 1 4T. If I have to use Avgas I’ll use Decalin and change the oil often.
Ed

And here we are using Shell Sport 4 thinking we couldn't be treating our planes any better. Starting to think we are nothing more than test pilots. My local pilot supply store had a good deal on the Sport 4 and I was going to get a bunch...glad I didn't. Is the Mobile 1 4T easy to get? Holy crap I am glad you made in down ok. 

[Glenn]

Sept 6, 2019 18:27:16 GMT buzz said:

Sept 6, 2019 12:32:30 GMT Ed Midgley said:

And here we are using Shell Sport 4 thinking we couldn't be treating our planes any better. Starting to think we are nothing more than test pilots. My local pilot supply store had a good deal on the Sport 4 and I was going to get a bunch...glad I didn't. Is the Mobile 1 4T easy to get? Holy crap I am glad you made in down ok. 

Most Walmart should have it available to order. Walmart near me has it.  $55 for 6 qt, $107 for 12 qt.  Free next day delivery.

[buzz]

Thanks Glenn.

[DavidOber]

Some more info to consider from the Lockwood FAQ:

What Oil should I run in my Rotax 4-stroke engine?

The oil that you want to use depends, to some extent, on what fuel you are using. If you are running exclusively automotive fuel, you can use a synthetic oil and go 100 hours between oil and filter changes. If you are running 100LL some or all of the time, you will want to change the oil you run based upon the 100LL use. Synthetic oil does not do a good job of suspending the lead and getting it from the engine to the oil tank.
If you are running automotive fuel most of the time, and go on a cross country, 3 or 4 times a year, that is long enough that you need to top off with 100LL to get home, you needn’t worry about changing the oil you use just for that. If you are running 100LL 30% of the time or more, Service Instruction SI 912-016 stipulates that you drop your oil and filter change interval to 50 hours. It would also be wise to change to an oil that is at least partially petroleum based.
If you are running Avgas 50% of the time or more, the same service instruction recommends that you drop your oil change interval to 25 hours. At that point you may want to go to an entirely petroleum based oil just because of the cost factor.
The oils that we recommend the most for those three categories are Mobil 1 Racing 4T (fully synthetic), AeroShell Sport Plus 4 (semi-synthetic), and Pennzoil Motorcycle Oil (a petroleum based oil).
SI 912-016 lists the requirements for oil quality, and also has some specific recommendations for oil brands and products. In all cases, and in all conditions we recommend that you stick with a motorcycle oil. Motorcycle oils are formulated for use in engines that have an integral gearbox and wet clutch – and that’s exactly what you’ve got in your Rotax. The only exception to that is AeroShell Sport Plus 4.
Sport Plus 4 was developed in an effort by both Rotax and Shell to produce an oil whose formulation was stable and well suited for the Rotax 4-stroke aircraft engines. It is, by the way, the only AeroShell product that is suitable for these engines. Do not use any other AeroShell product in your Rotax. The others are all intended for traditional aircraft engine types and will not treat your Rotax well.


So my summary of this is:

100% mogas - full synthetic (Mobil 1 Racing 4T) is recommended
Mix of mogas and 100LL (>=50%) - semi synthetic (AeroShell Sport Plus 4) is recommended

Since I run a mix...this will be a follow-up question to my mechanic's recommendation at my next visit as I am still running Sport Plus 4.

[buzz]

So I am confused a little Dave. How does this jive with Ed's situation with his dead stick landing. Up to this point I have only used 100LL and Decalin. Sounds like that since I am 100% 100LL and Decalin that I should be using Sport 4. But then how do I keep Ed's situation from happening to me?