B

bajabill

I'm New Here
Hello to all.
We are preparing for the first run on the 912 and I have a question for those of you who have gone before us.
We have read and understand the Purging the oil system info called out in the Installation Manual sec 13.10 but are not clear about the first run.
The 912 Install Manual page 133 Section 22 refers us to the Operators Manual sec 10.3 for details but our Operators Manual and the disc that came with the engine and all that I can find on the Rotax web sites have no sec 10.3. They all end @ sec 9.8?
We are very close to that first run and want to be sure we cover all that is required to protect the engine and warrante.
Thank you for any help and advise you can provide.
Bill & Dave,
120605
 
Welcome to VAF!!!!

Bill, welcome to VAF:D

Sorry, cant help you with the first run question, but I expect someone will jump in with the answer pretty soon.

Good to have you aboard.
 
To be sure - -

If you haven't done so, and you have done the oil procedure, as a sure way to know all is working well, take out the top set of plugs, turn on the main and av switch, and turn it over with the mag switches OFF. You should see oil pressure, say 60 PSI. If it is solid and good, put the plugs back in, burp it, and you should be ready for testing.

John Bender
396.9 hours as of this morning
 
First Run

There are some great videos on rotax-owners.com that walk you through some of the initial setup. It is $30/year to be a member but there is some great resources there.

As for the first run there are two things that Rotax says to do.
First is to pressurize the system. This is done by taking off the "in" hose on the oil tank and plugging the hole in the tank and pressurizing the breather tube on the oil tank with 10-15psi. Take out the top plugs and turn the engine over by hand until you see an indication of oil pressure. Reconnect everything and you will be ready for your first run. By the way, when you check your oil it will not "burp" unless the spark plugs are in.
If you have a helper it is very easy to do this. I had my brother hold his finger over the "in" hole on the oil tank and pressurize the tank with about 10 psi. Someone else watched the oil pressure and I turned the engine over. Took maybe 5-10 minutes.

On the first run Van's and the manual have a guideline for this. Start the engine, check that you get oil pressure in the first 10 seconds and maintain 2500 RPM until the oil temp reaches 120. Then you can run the engine up to 4000 RPM to check each ignition system.

After shutdown Rotax says you must remove each valve cover to verify the lifters have properly filled with oil. This is done by removing the top plugs, find top dead center of the compression stroke and use a soft hammer to put pressure on the lifters. If you see a gap larger than 0.020" between the valve and the lifter it has not properly pressurized. When I did this I had three lifters that were "soft". Trust me, you will know the difference between one that is solid and soft. If this is the case you can run the engine again for 5 minutes at 3500 RPM. You can do this 2 or 3 times.
After I ran the engine a second time for 5 minutes at 3500 RPM's all the lifters were solid.
Many on this forum say you don't have to do this and I don't quite understand why or how you would know if you had a soft lifter. If you have a soft lifter it says it will do permanent damage to your engine. The odds are very low but if you have a soft lifter it might be catastrophic and it took me 25 minutes to do the whole procedure.
 
Hi Scott,

This is good information.

The Rotax manual says:
- Disconnect oil line (2) at the oil tank connection.
- Place the free end (3) of the return oil line into a suitable container (4) below the engine.
- Plug open connection (5) at the oil tank with suitable air tight cap.

Was it necessary to take the oil line (free end) out in order to put it in a "suitable container below the engine"? I'm trying to think of a way to avoid taking this hose out as it would be a real pain to reinstall. Any information is appreciated.

Slane
 
Oil line

Hello, we did not pull the oil line out. I think we used a funnel with a Hose on the end of the funnel then into a bucket.
 
Routing the oil drain line to below the engine

Because during the oil purge procedure the plugs are out and there is no compression the engine cannot scavenge the crankcase of oil in the usual way. So, in order to be sure that the crankcase does not fill up with oil during the purge procedure the instructions say to keep the oil drain line below the engine.

It is unlikely that you would purge for so long a time that the crankcase would fill with oil, but the instructions must include that provision to cover all the bases.

It should not take very long to get the specified oil pressure indication. I have seen a Rotax trained professional do the oil purge a couple of times without keeping the drain line below the engine. Your call whether you do or don't.

Tony
 
Thanks Tony,
Appreciate the information and will proceed without taking the oil line out. If I don't get adequate pressure readings in short order, I'll stop and reconsider.

Slane
 
Tony, the rotax purging directions say:

Turn the engine in direction of normal rotation until the first pressure indication on the oil pressure gauge. Normally this will take approx. 20 turns. Depending on installation it may take up to 60 turns.

I turned the prop 20 turns and got a "2" for pressure. Then I turned the prop an additional 40 times and got a '3'. Does this qualify as "first pressure indication" or am I looking for 60psi?

Slane
 
Its a function of how fast you can turn it. The engine only pumps 60 psi when it's running. But, I have been able to see at least 10 to 15 psi when doing the purge and turning it as fast as I can by hand.

Tony
 
My first run experience

This is for what it's worth. I had my first run yesterday, assisted by a Rotax expert (he is managing the Remos of the local flight school and is Rotax certified):
- Pressuring the oil tank and rotating the prop, we brought the pressure up to 10 psi on the Skyview indicator. The unplugged return oil line cannot be brought down below the engine because of its tight routing. We just let it at the oil tank level.
- Engine start with choke and some throttle - Engine started immediately
- Idling was too high, about 2,400 rpm required repositioning of the stop tabs on the carb throttle cables. The Rotax man recommended 2000 rpm, a little higher than VANs PAP. His contention is that engine runs smoother at 2000 which will spare the clutch of the gear box (based on their flight school experience).
- We did not do carb balancing because the engine was running smoothly. He also pointed to the fact that the adjustments screws/nuts were marked as torqued by the factory which probably means that they performed carb balancing at the factory (he had the device needed for balancing with him if needed)
- Rotax man did not deem necessary to do the inspection of the valve tappets described in the Rotax SI. From experience a valve tappet not properly lubricated would make the engine running rough.
If you have no experience with Rotax I think it advisable to get help from a Rotax certified and experienced mechanics for the first run. Had I not done that, I would have had lots of questions unanswered and more work than really needed.
As a bonus, the first entry in my engine logbook will be signed by a Rotax certified technician which could be helpful in case of warranty issues.
If. like me, you don't even know what a smooth running Rotax sounds like, get professional help for your first run!
 
WingedFrog said:
If you have no experience with Rotax I think it advisable to get help from a Rotax certified and experienced mechanics for the first run. Had I not done that, I would have had lots of questions unanswered and more work than really needed.
Click to expand...

Not bad advice for other builders, but some of the advice the Rotax tech. gave you is not good.

An idle speed of 2000 RPM is going to make for loooong landings (if you can get it down at all).

He is correct that idling too low is hard on the gear box.
Just because the idle is set lower, doesn't mean the operator has to let it operate that slow during ground operations. Our airplanes have the idle set at about 1500. Our pilots are trained to always keep it in the green range during ground operations (above 1800).

The low idle speed allows the engine to idle slower during glide flight when landing. In this condition there is no risk of harm to the gear box because the prop is being driven by the relative wind.

I am also very suspicious about him not checking the carb. balance. That does not align with what any good Rotax tech would do with any new engine installation.

Good luck
 
Last edited:
rvbuilder2002 said:
Not bad advice for other builders, but some of the advice the Rotax tech. gave you is not good.
Good luck
Click to expand...

Thanks Scott, your advice makes sense to me and I will review this with my Rotax man. It is quite possible that the high rpm idle has less impact on the Remos, a high wing LSA than on the RV-12.
 
Y'all are confusing the carb balance with the mixture screws or something else. Carb balance depends on the installation of the 2-headed throttle cable. That has to be even. The carb balance adjustment is a fine adjustment of the nuts holding those 2 cable ends so that they are equally positioned and loading the 2 carbs equally when the throttle is advanced. That cannot be done at the factory, it is part of the builder installation. It is not a big deal to do.

Yes the factory does an engine test and adjusts several things. This isn't one of them.

You do NOT need to increase the throttle in the flare!!! At some point in the rollout you may get the low-engine-speed audible warning. There is your reminder. Follow the plans.
 
Spend the money and go to the ROTAX courses Lockwood and California Power Systems host. The service course is a must, and the maintenance course is a very nice to have. I attended both in March and feel much more confident doing my annual.
 
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