milky gearbox oil

[barrafan]

Is milky gearbox oil a major concern or does it just need replacing?

[Spaniard_King]

No real concern!! just need a new geabox soon if ya don't fix the leak:)

[Roughasguts]

Think you need to pressure test the gearbox, but first flush that gearbox out and replace the oil.

Oh yeah don't flush it with water, Maybe some Diesel /Kero or even light oil.

Replace the drain and filler plug seals then use some thread sealer to keep the water out.

But it maybe your gear box seal thats U/S and letting water in.

[barrafan]

Thanks for your help guys.I plan to get to work on the motor on tuesday.My day off.get some new oil and seals.and ask a few questions while i'm at the mariner.

[RTFM1000]

Hi barrafan,
pressure test it first. If is leaking around the seals dont muck around! If you are going to do it, do it correctly. New drive shaft seals, water pump housing gaskets or o'ring, shift shaft boot or seal (depending on make, model & HP), prop shaft seals and bearing carrier o'rings. Don't forget the drain bung washers. Do it right the first time as a replacement gear box is a very costly item.
If its a Yamaha, PM me.

Regards,
RTFM1000

[Noelm]

first off look for the very easy stuff first, and remember most people will not have anything to pressure test a gearbox at home! remove the prop amd make sure you have not got some fishing line caught behind it (braid is a seal killer) then replace the drain and fill plugs seals/gaskets, drain the gear oil, and flush if possible, refill with the correct type and give it a try, you will probably find line behind the prop, most have some in there, or if it is due for some repairs, then get them to pressure test the gearbox for you.

[Mindi]

Just changed my oil in a Merc 2 stroke (errr...dont ask how long since..!) and it was a bit milky but I had overcompressed an old washer on the bottom plug ...did not replace it last time...slack..! and there was obviously a slight leak....new seals under both screws cost me $2.80 ...woohoo.. dont reuse them they get distorted when tightened.

[Willdoe]

Pressure test tool - make your own.
Cut the head off a1" X 3/8" whitworth bolt. Drill a hole through the full length of the bolt. Get an old car valve stem with Valve intact, and cut some of the rubber off. Connect the unthreaded end of the bolt to the valve stem with a short piece of 3/8" plastic tube. Use Zippy ties to clamp. There you have it. (the thread on the bolt might be metric on some engines but 3/8 works for Mercs and Mariners. Just try a few.)

With gearbox drained screw the bolt into one of the oil holes (it might need some thread tape to seal. It should only take a small pressure to test. Excess pressure may cause leakage from good seals. With the leg off, Soapy water painted on the seal if you can get to them will show bubbles at the leak, otherwise submerge the leg in a drum of water. Some of the guys in the marine trade may have a different test method.

From my experience with Mercs it's generally the drive shaft seals located in the waterpump base. Be advised you will be lucky to find matching seals at your local bearing supplier. I'm convinced they deliberately make them non standard so they can charge an arm and a leg for them.

Willdoe