Gearbox Seal Oil Seepage

[Bulldog]

Hi everyone - It looks like I have oil seeping out of the bottom part of the gearbox seal. It's enough that it's making a mess of cylinders 2/4. Has anyone had success in attempting to seal this type of leak without removing the gearbox? 

Thanks,

Nick V

N663CT

[Bulldog]

Thanks @Roger Lee! I’ll let you know - I’m going to try to make the decision soon as to whether I’m going to try to tackle it myself. 

[Tom Baker]

Like Roger said it is not hard, but I think his 30-40 minutes is a little light. You will need to remove the propeller and fuel pump. You should probably replace the fuel pump isolating flange. You will need a puller. It is $554.65 from Rotax, but one can be fabricated using some angle iron, bolts, and a slide hammer.

One thing I do when applying sealant is to cut some 1.5" wide strips of paper and roll them up and insert into the bolt holes. This will help keep the holes clean when applying the sealant. Also, make sure the sealing surfaces are really clean.

 

[Bulldog]

Thanks guys! After reviewing the maintenance manuals and watching one of Jeremy Macgregor's videos, it doesn't seem too bad.

Aircraft Spruce has a puller in stock for $108 here:  https://www.aircraftspruce.com/catalog/rtxpages/15-05923.php

How does this look for a checklist:

1.       Warm engine

2.       Burp oil

3.       Install crankshaft lock

4.       Remove spinner and prop

5.       Remove fuel pump

6.       Remove 2 M8 bolts on bottom of the gearbox

7.       Remove 8 M6 bolts around gearbox

8.       Attach the gearbox puller slide tool using 2 M8 bolts on the side of the gearbox

9.       Hold bottom of gearbox with one hand and be ready to catch

10.   Use several quick taps on the slide tool

11.   Remove slide tool from gearbox

12.   Cover/mask gearbox rear half

  a.       Use Loctite 7063 (or equivalent) to clean mating surface

13.   Cover/mask gearbox front half

  a.       Use Loctite 7063 (or equivalent) to clean mating surface

14.   Dab Loctite 598 on the front half mating surface

15.   Line up and install gearbox

  a.       Move the propeller shaft a little to allow the drive gear to engage

  b.       Tap gently on the gearbox housing with a soft-faced hammer to position the gearbox on the crankcase

  c.       If there is a large amount of resistance at a gap of approximately 10 mm, the bearing rollers of the roller bearing may not be in position

16.   Lightly seat all bolts, then

  a.       Start by torquing the M6 bolts at the 3 o’clock and 9 o’clock positions

    i.      Torque the 8 M6 bolts to 10 Nm (89 inch lbs)

  b.       Work in a star pattern (diagonal), ending with the M-8 bolts

    i.      Torque the 2 M8 bolts to 24 Nm (18 foot lbs)

  c.       Final torque on all bolts

17.   Install fuel pump

  a.       Secure hex nut M8 with lock washer A8 with LOCTITE 243 and tighten evenly

  b.       Tightening torque 15 Nm (133 in.lb)

18.   Install spinner and prop

  a.       Prop bolts torqued to 175 inch lbs

19.   Remove crankshaft lock

[Tom Baker]

I'll see if I can post the Neuform manual tomorrow. When removing the propeller loosen the three smaller bolts first, then just tighten them until the touch. Then loosen the six that hold the propeller on. If you don't do this it is possible to pop the heads off the small bolts.

Also slide something in between the engine and the radiator to direct oil away from the engine, because there will be oil that pours out of the gearbox.

[Tom Baker]

When the propeller goes back on tighten the nuts on the six M8 screws in a crosswise pattern to 27nm or 19.91 (20) ft/lb. Then tighten the three M6 screws to 10nm or 88.5 in/lb. My preferred way of torqueing the prop nuts is with a torque adapter turned 90° to the torque wrench. These also work well for torqueing the nuts on the fuel pump. I have used a universal impact socket for the nuts before, but the adapter works better. 

Neuform Propeller.pdf

[Tom Baker]

Warming the engine and burping are probably not necessary.

Unless you are planning to removed the crankshaft gear, locking the crankshaft is also probably not necessary. 

Make a chute like in the picture to keep oil away from the radiator and oil cooler, and have a drip pan or bucket for the oil.

Before installing use some grease to hold the rollers on the bearing in place for installing the gearbox. I have some white grease mixed with STP that I use for engine assembly that I use. Also put a dab of grease on the plunger for the fuel pump as it goes back on.

New lock washers 945-832 for the fuel pump would be a good idea, and as I mentioned above a new isolating flange 950-228 should be used.

Six new DIN 985 M8 locknuts for the propeller. 

[Bulldog]

Thank you guys! Now to plan when exactly I want to tackle it.

[Tom Baker]

21 minutes ago, Roger Lee said:

I just use a CrowsFoot wrench. Works well. When I pull the gearbox off I just place rags under it and on the floor. Pull the box off and tilt it upward quickly. Less oil spill. Plus there is a little less oil when the engine is cold vs hot.

When I pull a pull a prop I only remove ther 6 through the flange bolts and never loosen the center hub ones. The center prop hub bolts should not be affected. In 23 years and hundreds of props I've never had an issue. When I re-install the long bolts I torque them in three stages and in a cross pattern. I just did two gearboxes and no issues.

Rotax (from the factory) uses Copper anti-seize for things like the fuel pump plunger and when assembling the gearbox. I put Copper anti-seize on metal moving contact parts in there gearbox. You don't need to use a bunch. I learned this in the many Rotax classes I took. Just enough to lube the dry metal parts until the oil starts flinging around inside. Don't use just any grease or lube. Some are not compatible with the oil and system. usually the White Lithium Grease is used for the engine "O" rings. It is compatible with oil and fuel. When it gets hot it turns back into an oil vs staying solid and clogging things.

The torque adapter works better than a crows foot because it fully captures the nut, and you can't get to the bottom fuel pump nut with a crows foot. I have used a wrench and a scale for the bottom nut before I purchased the torque adapters. 

Regarding removal of the propeller. The popped heads on the M6 bolts I think came from Arian. It is something I have always done. While the propeller maintenance manual doesn't say that the bolts will be damaged it does say to loosen them before loosening the six M8 bolts. I try to follow the maintenance manual to the best of my ability, especially since it is required by regulation.  

I don't find any reference to lubricating the plunger in the Rotax manual or the SB on fuel pump replacement, but it is something I picked up in my Rotax training along the way. The lubrication I use is an engine assembly lube. It will fully dissolve in the oil. 

[Tom Baker]

I have a home made puller that I use, but when you posted that link to the one from Aircraft Spruce I added it to my shopping cart. They showed 3 in stock at that time. By the time I got around to finishing my order they were out of stock. I figure you created a run on them by posting here.