Purging 912ULS oil system with oil thermostat installed, heat oil and oil thermostat to 200F.
The attached document is for a 912S, but should be the same as my 914 with Mocal oil thermostat.
January 2nd, 2011 3.0 hours - Purge oil system
I had filled the oil tank with Aeroshell Oilsport Plus 4 oil two weeks ago and ran through the oil purge procedure described in Rotax Service Instruction SI-912-018 & SI-914-020. I used VDO oil pressure calibration data and measured the resistance of the oil pressure sender during the procedure to confirm that I was getting oil pressure in the 40-50 psi range. This satisfied the criteria described in the procedure.
I had asked California Power Systems about purging the oil circuit with an oil thermostat installed. They said that the thermostat will always pass some oil through the cooler, even when the oil is cold, so nothing special would have to be done, other than to keep turning the propeller until the oil cooler is filled with oil.
So, I disconnected the oil return line at the oil tank, capped the tank opening, hooked up my air compressor, removed the top spark plugs and tried the purge. I wasn't able to achieve the specified 10-15 psi of pressure due to the rate of leakage at the oil tank cap, but the oil seemed to be getting through the system, because I was getting good oil pressure and there was oil coming out of the return line from the engine.
I wasn't sure the oil cooler was getting oil, so I disconnected the oil line at the top of the oil cooler and found some presence of oil there, but the line and the oil cooler both appeared to be empty.
The Rotax Service Instruction ways nothing about what to do with regard to the oil thermostat, and the oil purge video on the Rotax Owners web site merely says "If there is an optional oil thermostat installed, it will bypass the oil cooler when cold and feed through the oil cooler when warm. Extra attention should be given to ensure this circuit is properly purged of air." But I couldn't find any specific instructions about what that "extra attention" should be.
I reasoned that I could heat up the thermostat with my hot air gun and get it to open. So I tried heating up the thermostat until it was hot to the touch and tried the oil purge again. Then I checked the oil line at the oil cooler, finding that it was still empty.
After further research, assisted with input from the Rotax web forum, I concluded that I needed to heat both the oil and the thermostat in order to get oil throughout the oil circulation circuit, including the thermostat and the lines to and from the oil cooler. I also concluded that I needed to do something to get the pressure in the oil tank up to 10 PSI.
I drained the oil tank into a pan and heated the oil to 200 degrees F on the kitchen stove, and I used my heat gun to get the thermostat fully heated to about 200 degrees F as well. I used an IR thermometer to check these temperatures, although I found that the IR thermometer has trouble measuring temperature consistently on a shiny metal surface such as the oil thermostat.
I also found that if I pressed down on the oil tank cap while applying air pressure, the air compressor was able to keep up with the leakage and achieve the 5-10 PSI required to move oil through the system.
So, I put the hot oil in the oil tank, got some help to turn the propeller while I maintained pressure on the oil tank cap and used the heat gun to maintain the temperature of the thermostat. This time a check showed that the oil tank and return line were full of oil, so I secure the oil line and repeated the purge one more time to remove any air introduced when I checked the line.
Then I reconnected the lines to the oil tank, safety wired the drain plug and secured the fittings and hose clamps.
Another post:
--> RotaxEngines-List message posted by: "Roger Lee" <ssadiver1@yahoo.com>
You can use a heat gun on the thermostat to open it up for a good purge and as
suggested look at the video on the ROAN website. It is very good in showing you what
to do.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Here is the original post to the Rotax group:
Subject: Re: RotaxEngines-List: Purging 912ULS oil system with oil thermostat installed
From: "Paul Kuntz" <paul.r.kuntz@gmail.com>
Date: Tue, March 15, 2011 11:38 pm
To: rotaxengines-list@matronics.com
Priority: Normal
Options: View Full Header | View Printable Version | Download this as a file | View Message details | View as HTML
LS,
I discuss this on my Pipistrel project web site. Here's a link to the Firewall
Forward page <http://www.pipistrelbuilders.com/firewall_forward.html>.
Scroll down the page to the entries for
Dec 5, 2010, Dec 18th, 2010 and Jan 2nd, 2011. I found that the partially
open position of the thermostat when cold wasn't enough to get all the lines
full of oil, and you definitely want to get all the air out of them.
I would check the lifters as well, although they may remain full of oil.
The problem is that you will be turning the prop through a number of
revolutions before the system is full of oil again, so the oil may be
squeezed out of the lifters, at least to some degree. Follow the procedure
described in the Rotax 912 Installation Manual, section 31.11 (available in
the Documentation
area<http://www.rotax-aircraft-engines.com/desktopdefault.aspx/tabid-49>of
the Rotax web site). It will be easy to see of the lifters need to be
re-primed. There is also a video of the priming procedure available
on the Rotax
Owners site <http://joomla.rotax-owner.com/>. If you don't already have a
subscription to this site, I recommend it for an excellent information
resource (in addition to this forum).
Regards,
Paul Kuntz
Pipistrel Sinus 912 kit serial 196 <http://www.pipistrelbuilders.com/>
On Tue, Mar 15, 2011 at 3:48 PM, lucien <lstavenhagen@hotmail.com> wrote:
> --> RotaxEngines-List message posted by: "lucien" <
> lstavenhagen@hotmail.com>
>
> Hi all,
>
> I'm going to be replacing my oil lines soon but I've never done a full
> purge and reprime of a 912 oil system before. So have a couple questions
> about it:
>
> - I have an oil thermostat installed like this one:
> http://www.rotaxparts.net/scripts/prodView.asp?idproduct=1302
> Is there anything in particular I have to pay attention to to make sure the
> oil cooler gets properly filled up with this inline? The documentation for
> it says it's partially open even when cold so I assume it fills up by
> itself. But not sure. Anyone know?
>
> - the manual says to pull the valve covers off and physically check for
> play in the lifters afterwards (i.e. for the presence of air in them). Is
> that necessarily still after just breaking the oil circuit open to change
> the lines? Don't know if that's only for new engines or ?
>
> Thanks,
> LS
>
> --------
> LS
> Titan II SS
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=334002#334002
FYI: MoCal is the name of the Manufacturer. I purchased my FWF from Europa
and the oil cooler is made by MoCal as well.
Anyway here is the
place I bought it from:
http://www.batinc.net/mocal.htm
It's the one on the right:
http://www.batinc.net/thermos.htm
This one opens the bypass at lower oil temps, so there is still
some oil flow through cooler.
Subject: SV: Europa-List: Purging a Rotax with an oil thermostat.
From: "Sidsel & Svein Johnsen" <sidsel.svein@oslo.online.no>
Date: Wed, March 16, 2011 3:57 am
To: europa-list@matronics.com
Priority: Normal
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--> Europa-List message posted by: "Sidsel & Svein Johnsen"
<sidsel.svein@oslo.online.no>
Alternative to heating the oil to open the thermostat for purging the system
after installing the thermostat:
My thermostat is mounted on top of the right side footwell. I simply filled
the "U" comprising cooler and both tubes with oil before connecting the
tubes to the thermostat. Fill slowly through one tube until the oil comes
up through the other, wait some minutes to see if topping up is needed
before connecting. Hold both tube openings at same level, of course.
The thermostat was not mounted in place when connecting the cooler side
tubes to it. By holding the tubes vertically and pushing the thermostat pipe
ends down into the tubes, air pockets inside the thermostat on the "cooler
side" will be avoided or being very small.
Best done with oil temperature as on a mild spring day, to assure easy flow
through the cooler when filling the "U".
Purge as normal after connecting the other tubes and fixing the thermostat
in place.
This worked fine for me, and was not a messy operation.
Regards
Svein
LN-SKJ
Y11-03-16
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