Jabiru oil leak resolved

[fastj22]

For years, I've chased a small oil leak on my Jabiru3300. The symptom was a misting oil somewhere near the prop hub and would mess up the cowl and all things past it. Not much, just a mess. I suspected the oil pump cover and removed, cleaned and resealed with the indicated goo. Still no joy. After the B-model conversion and the engine sitting for a year, the leak got worse. now I was blowing an ounce per hour into the cowl. Removed the oil pump cover, resealed with PermaTex. well that worked, not in that it sealed the cover, but blew out and made it very apparent where the leak was coming from. Again remove, clean and apply the correct anaerobic sealant (Loctite 515 and 7649 primer) called out in the manual. This time it worked. Not a drop or a mist. Persistence paid off.

[Sonex1517]

Thanks for posting this John. I’m suspicious I have a very similar leak. Based on what I see this could be the cause.

[fastj22]

There are actually two seals on the cover. The cover itself has an o-ring. The pump plate that the gears orbit in is a metal to metal seal against the case. This is the one that was leaking. If you don't get right amount of goo or the surfaces are not prepped properly or for pete's sake you use the wrong goo, the pressure will blow past this. I suspect the sealant cracks over time and allows a small seep of oil to escape at fairly high pressure thus misting it. Note: read the maintenance manual prior to taking this apart. Things go back together in a specific orientation and there's a woodruff key that will surely try to escape.

[Sonex1517]

John

I didn’t find the reference in the maintenance manual. Which section or page should I be looking for?

Thanks

[sonex892.]

I didn’t find the reference in the maintenance manual. Which section or page should I be looking for?

Robbie. Look in the overhaul manual. https://jabiru.net.au/wp-content/upload ... Manual.pdf Pages 49,73 and 158.

Its a new manual hot off the press.

Steve
Sonex 892

[Sonex1517]

Thanks! That is definitely fresh material!

[Sonex1517]

In case anyone else needs to do this, I thought I’d expand on the explanation of how.

I used ENGINE OVERHAUL, ASSEMBLY AND PARTS BOOK FOR JABIRU GENERATION 4 2200 AND 3300 AIRCRAFT ENGINES
DOCUMENT No. JEM0004-6 Dated – 30/05/2020 (thanks Steve!)

Found here - https://jabiru.net.au/service/manuals/

There are multiple variations of the pump and plates now. The pump has a four lobe version and a six lobe version. My generation 4 engine has a six lobe pump but the back plate does not have the groove and gasket that the latest version apparently has.

I had purchased Loctite 515 and 7649 primer as John mentioned. (It appears Loctite 518 is a suitable replacement) I found removing the prop was the easiest method to get the pump off. Pulled the 4 cap screws and worked the cover off, then carefully removed the oil pump inner and outer gears off. John is quite accurate in his description that the woodruff key is an escape artist. I then worked the pump back plate off.

All of this took less than 30 minutes.

I thoroughly cleaned everything, dried it and removed any residual sealant. Cleaned it again, dried it again, then applied the Loctite primer all over the faces. I put oil on the gears and in the cover per the manual.

Getting the woodruff key and inner gear back on was a bit trying, but I just took my time and it worked.

I smeared a layer of Loctite 515 on and then carefully reassembled things. One important note is the need to only tighten the cap screws finger tight at first, then put the prop back on and rotate it a few turns to ensure the gears and housing are not bound up. Then it’s safe to tighten and torque the cap screws.

After a test flight today, no more seepage. I hope it stays that way.

[fastj22]

Excellent work Robbie.
Like old men, excitable women and Harley Davidsons, they tend to leak.

Mine is high and dry until the sealant cracks again.

[Sonex1517]

Hopeful mine stays the same. Thanks John!