fbpx

 

Hello,

We are building a Zenith CH750 CruZer with a Rotax 912 ULS. The motor came with a "80 degree bent socket" for the water pump, what however causes some clearance issues with the engine mount bracket.

As per the service part catalog, a 45 degree fitting #922-232 would be available as well, what would help with clearance.

Has somebody ever replaced this fitting? I understand that the water pump housing needs to be heated to get it out and that there is the risk of leaks down the road.

It also appears as whether the fitting has been discontinued, I am therefore also open for alternative ideas.

Oliver

8644_1_IMG_0946.jpeg (You do not have access to download this file.)
8644_1_IMG_0945.jpeg (You do not have access to download this file.)
  • Re: 912S water pump 45 degree bent socket?

    by » 3 years ago


    After reading the Loctite 243 SDS, according to which it is only a "medium" thread locker, that "normally" doesn't require heating, I gave it carefully (really!) a try and (of course) immediately stripped the thread. ?

    I'll now have to heat the housing up to clean out the remaining thread locker. Time for a new water pump gasket and 45 degree fitting!

    Leading Edge Air Foils has the 45 degree socket in stock, seem like the alternative part number is 922-238


  • Re: 912S water pump 45 degree bent socket?

    by » 3 years ago


    It really didn't matter.
    As you found out, They are so thin-walled, you were going to destroy it no matter how careful you were.
    If I recall the thread is M18x1.25, and you will need to clean up the threads in the pumps.  Measure what came out.
    They need to be perfect.
    The Hose Sockets are a very soft alloy and will bind and cross-thread for the slightest excuse.  
    Whisper nice words to them and play soothing music while trying to thread in the new one.  

    Whatever you do, do NOT try to DRY-Fit one.
    It will spall and jamb in a heartbeat.
    I found that a good flood of lacquer thinner will act as a temporary lubricant and allow you to get it in.
    If it hits bottom before aligning, back it out.
    Do not try to thread it in firmly.
    STOP turning at the slightest resistance.

    My method was to thread it in with the solvent.
    Blow-dry the connection with compressed air.
    And when you are double sure it is pointed in the correct direction, Flood the threads with #290 Green Wicking Loctite.

    #243 Blue may also work if it a brand new fresh sample that has not started to thicken.
    Twist the joint slightly to assist in getting the Loctite to migrate

    I also believe that just using the #243 as the installation lube will work just fine but remember that you will only get one shot at getting it right.
    I was too chicken to try the Go For Broke method because the fittings are not cheap.

    I changed 4 of them in a thermostat housing.  I used 6 in the process.
    If you only need to replace one, I would order 2 for insurance.

    The factory guys probably have the technique down pat, but we don't do enough of them to perfect the process.

     


    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated by Everyone.


    Thank you said by: RotaxOwner Admin

  • Re: 912S water pump 45 degree bent socket?

    by » 3 years ago


    I have found these quite easy to deal with. I always heat  them at the base real good. When heated enough the will just turn out by hand. By doing so have never ruined one. You can use a heat gun or a small butane torch. Once heated well they all just unscrew fairly easy. If it won't turn by hand you haven't heated it enough to loosen the old Loctite. To prevent them from leaking ever again I use Loctite 648 (green) to secure them back in place. I let them sit overnight before putting fluid back in.

    p.s.

    Before I loosen them I take a black magic marker and mark the flange and tube so I know exactly where to clock it in its fitting again.

    And as Bill stated never wrench down past the point it starts to have resistance at the bottom of the threading process. Back it out a turn. The Loctite will hold it in place.


    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell


    Thank you said by: RotaxOwner Admin

  • Re: 912S water pump 45 degree bent socket?

    by » 3 years ago


    877570 .TAPPING DRILL M18X1

     

    OK for starters that is the Rotax part number for the tap to clean up the threaded body of the water pump housing.  It is the exact same thread size as the flange on the coolant inlet in the heads and the return.  18 X 1.  Note that if you want to source your own tap please get a bottoming tap and not regular one.  A bottoming tap is less tapered at the end.  Additionally note that it is a straight thread, not a pipe thread, this is why we use Loctite and do not want to overtighten the tube on placement. 

    Here is what I do and yes I can save most of the fittings this way.  First be sure of the clocking of the pipe to your desired position.  If it is the water pump housing the best is to remove it and do this work on the bench and not in the aircraft.  (my opinion) 

    1 clamp the  housing with some soft jaws to not damage your gasket surfaces.  When you do that I will put a small line on the housing to the fitting to clock it back into the same position.  You will find that with the 80 degree fitting it is better to remove the lower 45 degree first then the 80.  Normally I take both off one side to have more room. 

    2  make a small piece of dowling from wood to give yourself a handle.  It should fit into the tube at least 25mm (1 inch) and be the correct size.  Avoid using metal tools that are too small as they will put too much pressure in one spot when we twist the pipe.  Allow a handle say double your hand width to stick out.  

    3  heat the housing not the nipple.  Git it up to about 80C (176F) and the Loctite will soften.  Now gently remove the tube.  (remove the 45 first, then the 80 degree) 

    4  Let it cool then use a small soft brush remove the Loctite powder from the threads on the nipple you need.  Use your bottoming tap (18X1MM) and run it into the casting to clean up the residual Loctite powder.  

    5  When all clean put your Loctite on the thread of the niipple and insert it to the casting.  Be sure to have at least 3 full turns engagement.  Get your alignment and then simply allow it to cure for at least 1 hour.  (24 hour is full cure)  Some people will say to add heat to speed the cure but I prefer not to do that.  Loctite says fixture time is about 5 to 10 mins, I allow an hour as museling on the hoses might cause it to break away otherwise.  If you really want to be sure then wait till morning to finish it up. 

    Note to all:  If your not confident on the 243 holding in your application you can switch to a stronger seal/locker for the tubes.  Many use Loctite 648 green in this application.  It is far stronger and more of a cylindrical bonding compound but was used by Rotax in the past for this part.  it will be more difficult to remove however should you need to do a repair in the future.

    Cheers


    Thank you said by: RotaxOwner Admin

  • Re: 912S water pump 45 degree bent socket?

    by » 3 years ago


    Hello everybody,

    Thank you for all your responses, this is extremely helpful.

    I guess I should have waited for answers, before I gave it a try.... ? ?

    Oliver


You do not have permissions to reply to this topic.