Rotax 912 water pump housing - angle change for coolant fitting

[Marty_d]

Hi,

 

As I'm using the Rotax ring mount, the coolant fitting for the number 2 cylinder needs to be rotated in order to clear the ring mount.

 

The fittings have a fine thread and are coated with Loctite 243.  The Rotax Heavy Maintenance Manual says to heat the housing up to 80 degrees in order to loosen the fitting.

 

Someone's already told me that they moved theirs by heating with a blowtorch.  My question is - is there a danger of warping the housing by uneven application of heat from a blowtorch?  Is there a better way to do it, for instance bunging it in the oven?  (The housing has of course been removed from the engine!)

 

As always, all advice gratefully received.

 

Cheers, Marty

 

 

[Downunder]

Nah, it's easy and doesn't take much heat.

 

Grip the tube. Put some "weight" on it and warm the tube.

 

Heat will run down the tube and free it up....

 

Make sure it is spotlessly clean on re-assembly. ...

 

 

[skippydiesel]

Nah, it's easy and doesn't take much heat.

 

Grip the tube. Put some "weight" on it and warm the tube.

 

Heat will run down the tube and free it up....

 

Make sure it is spotlessly clean on re-assembly. ...

 

Sounds about right - BUT - as with all things care should be applied in bucket fulls. You might want to try using a heat gun rather than a blowtorch and be carefull with the "grip" device least it leave some nasty score marks, a noarow (than the ID of tube) bar might be  less aggressive..

 

 

[skippydiesel]

Oh!  one other point, the title of this thread is a little misleading - it would seem you want to realign one of the engine coolant pipes - Downunders excellent advice.

 

The "water pump housing" however can simply be rotated, to better accommodate the angle of the radiator hose or to clear an engine mount stay - from memory at least two positions are available.

 

 

[M61A1]

I  made a snug fitting bar that goes in the outlet. ( a solid piece of alloy bar with a 90° bend in it for good access)

 

As the fitting gets hot you will see the Loctite change colour, I really don't think that 80° is adequate (otherwise they would leak when the engine is at operating temp), but care must be exercised.

 

As Downunder said, apply a bit of pressure while heating and you will feel it start to move. Care is required because they are soft to start with and very easy to distort.

 

If you should wreck one, they are one of the few reasonably priced Rotax parts, around $16 from memory.

 

Yes, I wrecked one, because 80° isn't enough.

 

 

[Blueadventures]

Hi Marty

 

Try dropping it into boiling water 100degC  or phone Floods and they will have some advice on what to do. 

 

If you use a flame torch keep it moving to apply the heat increase slowly and you could mount the housing to a piece of timber held in a vice or clamped to a work bench and fasten with bolts or screws so it's firm when undoing using welding glove on the pipe; that way you won't apply too much pressure and bust it.

 

 

[IBob]

Hi Marty, I shifted mine using a piece of dowel up the pipe end. Fortunately, they move pretty easily on the pump housing, and it's not hard to play a butane torch on the pipe, rather than the housing.

 

I have also replaced a pipe on the underside of a cylinder head. This uses a different Loctite, requiring a fair bit more heat, and I made a simple mask out of scrap sheet steel, so that only the pipe was directly exposed to the flame. You could also do this with the pump housing, if you were concerned, though I don't think it is necessary.

 

In the case of the cylinder head I removed and replaced the pipe. I found a 28G shotgun cleaning brush useful for cleaning the thread in the head (in a perfect world you would do this with the appropriate tap). These are fine threads in soft material, and do need to be treated with care. If removing and replacing, take time to carefully clean the threads, and make sure Loctite is applied to both surfaces before fitting.

 

 

[cscotthendry]

Be very careful with the elbow. They are thin and very soft. A good heat source is a heat gun, don't use a blow torch. A close fitting dowel into the tube is a good ide as others have said, but don't put a lot of force on the elbow or you'll be up for a new one. And whatever you do, don't grip it with pliers or a pair of multi grips.

 

Ask me how I know that!

 

 

[facthunter]

IF you are loctiting any fitting  threaded,  or a long pressing be aware of the Loctite starting to set before it's home. Keep everything cold if there's any likelihood of a problem. Some loctite s are higher temp resistant so won't "relax" as easily. Nev

 

 

[onetrack]

Loctite requires 260 deg C to soften and release. I'd be heating the components in an oven to 260 deg, to get an even high temperature.

 

Be very careful with the softness of aluminium once heated to that temperature. It will lose one-third of its strength at that temperature.

 

 

[IBob]

Hi Marty, as Downunder has indicated above, it's really very straightforward.

 

I used a dowel about 90mm long fully inserted in the elbow. Just heat the elbow a bit, then feel with the dowel if the elbow will rotate, heat a bit more if not etc It's sort of gummy but there is no great force required.

 

The cylinder head ones are similar, but require a lot  more heat as they use Loctite 648.

 

 

[Marty_d]

Thanks folks.

 

Good advice there.  I'll clamp it to the bench and try with the heat gun, if that doesn't work it'll be off to Bunnings Aerospace for a torch.