912 oil pump

[Pat Oden]

Is the 912 oil pump a gerotor(sp?) type of pump. Also would that make it self priming? I'm slowly but surely coming to the conclusion that I can put a resevour(sp) behind the water radiator with oil lines going to the pump suction and out of engine at the banjo fitting on the sump.

Thanks in advance for any information on the pump.

[Av8r3400]

Why?

The Rotax oil sump is of a design to flow, cool, reduce foaming and several other things specifically for the 912. Why are you needing to replace it?

[Pat Oden]

Why?

The Rotax oil sump is of a design to flow, cool, reduce foaming and several other things specifically for the 912. Why are you needing to replace it?

I don't want to replace the oil sump, just lessen the amount of oil that stays in it by making additional resevour(sp) down low behind the water radiator. The tank I have designed will hold approx. 262 cubic inches of oil not including the hose volume. This location will allow additional cooling.

The whole idea is to lessen the amount of oil that lays in the engine sump so a "hydraulic lock" situation won't occur hopefully.

My only concern was wheather the oil pump is self priming, I think it is but I was asking the fourm about that.

I'm not trying to reinvent the wheel just help make the system better.

Pat

[jiott]

Like most any positive displacement oil pump, it is usually self-priming. However, this is not 100% reliable. It depends on the clearances (new or worn) in the unit, the presence of oil to wet and seal the clearances, air pockets, etc. That is one of the reasons Rotax tells you to purge the system with air pressure after breaking into the system.

If you need more oil cooling why not just install a larger oil cooler; much easier, simpler, and doesn't mess with the well proven design of the system. If you burp the system before startup as you are supposed to do anyway, there is no problem with hydraulic lock.

[Av8r3400]

As to the oil hydro-locking is concerned, the newer Rotax oil filters have solved this problem with an anti drain back valve. I have never had an issue with this on my motor. I believe the cases to be very rare, or no existent since the introduction and use of the updated filters.

You always need to pull the motor through to check the oil, so should a failure happen in the check valve you would know right away.

Another point would be if you are using a new motor, any modification like what you propose will likely void any warranty.

[Pat Oden]

I have installed a rotax oil filter and it doesn't seem to keep the oil out of the back two cylinders.

Again I ask, is the rotax 912 oil pump a "gerotor" style pump. If so it should be self-priming. Can anyone confirm that this oil pump is self priming?

I really would appreciate the help.

Pat

[Av8r3400]

LEAF's online catalog, page 97 shows the pump. It is a gerotor style pump.

http://onlinecatalog.leadingedgeairf...?RelId=5.3.6.2

I would counter that you are masking another problem, perhaps something serious. As I said before if you are using the new style filter, you should not be getting oil flow back into the crankcase.

I would suggest contacting Brett Lauton at LEAF. 1-800-532-3462, ext.154.

[Paul Z]

I would check the compression, and then valves. It sounds like you may have a problem with leakage around the valve stems, or the rings.

[henrysamson]

My model 4 with a 912 sat for 5 months while I was away recently. I had a hydraulic lock due to oil in the left rear cylinder. New type oil filter and about 10 hours since an oil change. I just assume enough oil siphoned back into the engine to reach the level of the cylinder.

Henry

[SkySteve]

the newer Rotax oil filters have solved this problem with an anti drain back valve

I was told (a long time ago) that with the manifold reversed on the older 912's, the Rotax oil filter would not fit. As a result, I've never used one. I'm willing to try now that they have apparently solved the drain back issue. But, will it fit or is it too long and will it therefore hit the exhaust header? There's not much space there.