Water in lower unit ?

[HighlandR]

Hi guys, just got our engine out to give it a service before using.
We bought it 2nd hand and have not yet used it.

So began by draining the lower unit oil, there was some white in the oil which I believe indicates water, so let the oil sit over night to see if the water would seperate and float on top.

Have added a photo, is this oil normal colour for being old, or is there water in, meaning a seal or seals need replaced ?


I'm just wondering if a small amount of white is normal after being in there a while ( at least 2 years ) caused by condensation etc ? or is there definately a seal leak ?

What would be the next most logical step ?

I also wish to change the impellor, is this easily done by yourself or is it specialist job ?

I have a reasonable set of basic tools, mostly repair our own cars etc..

Would like to take it to the local marine workshop but the prices are pretty high so would rather attempt it myself first if it is do-able, or do i bite the bullet and shed out the hard earned cash !??

[A1an]

I wouldn't worry about that oil, looks ok in the picture. It's certainly not badly contaminated. Like you say, it may just be a little bit of condensation water.

Fill with fresh oil and replace the washers behind the drain/fill plugs. Next time you drop the oil dry and do it into a tray, I find it easier to spot the water when the oil is spread over a wide area than in a full jug.

If you are confident at all with spanners then the water pump is easy enough.

When I get an engine with an unknown history I usually give it the works. Plugs, stat, water and fuel pumps and oil change with new washers. When replacing the water pump I usually replace the cup too, not just the impeller then whip prop off to check for fishing line/debris around shaft and grease the splines.

[HughN]

Unbeknownst to me the lower unit on my engine was running with only water in it. It ran well and no damage was apparent when it was taken apart to be repaired.

It also drained a lot quicker than oil does!

[HighlandR]

Hi Alan, thanks for the quick reply. I drained it into a flat tub but then just poured into the bottle to see any water seperation better.

Here is a photo of the remains in the flat tub, and also the base of the bottle, white milky sludge.

Does this still look ok ?

[HighlandR]

Hugh, was the engine run in fresh water or salt ? You seem very lucky !!

[jyasaki]

Checking the LU for leaks generally involves slightly pressurizing it and seeing if it holds the pressure. Not rocket science, but takes some specialized fittings (generally a threaded adaptor into the fill port, with a gauge and a handpump sitting off of it.)

If I remember right, I think Yamaha specified about 3psi (definitely verify that before trying.)

jky

[A1an]

Yep you have some water contamination in there alright, could be down to dodgy seals or something simple like bad washers if they weren't replaced after last oil change.

If it was mine I'd fill it back up with fresh oil, put new washers on, put a few hours on it and check the oil again, if you leave the oil to settle overnight in the gearbox and check the next day any water should be at the bottom of the box and be the first to appear when you open drain plug.

If water was present I'd be digging a little further in to the problem.

[Searider]

Guys,

Surely the water will be emulsified into the oil and won't settle out?

[A1an]

It does to an extent, with light contamination itl settle to the bottom as a milky yellow fluid, heavy contamination you find ALL the oil is a milky yellow fluid.

[Landlockedpirate]

Originally Posted by Searider

Guys,

Surely the water will be emulsified into the oil and won't settle out?

Yep, spot on. The gear oil is designed to combine with the water, so even if water gets in, the oil will still do its job. It wont settle back out.

I wouldnt start worrying about yet, lots of engines never have a gear oil change. I recently serviced a friends early 80's Yamaha that still had original oil in it

But its a really important job, Dad trashed the lower end of a nearly new Yamaha 90hp when I was a kid, when a oil seal failed and the contents of the gearbox became more water than oil

[A1an]

Originally Posted by Landlockedpirate

Yep, spot on. The gear oil is designed to combine with the water, so even if water gets in, the oil will still do its job. It wont settle back out.:

If the previous owner used the correct oil.

Whenever I've dropped oil out the LU the milky bit is always first out the drain hole.

[Landlockedpirate]

Originally Posted by A1an

If the previous owner used the correct oil.
.

Fair point

[HighlandR]

Just double checked and found there was no seal or washer on the drain plug, only a rubber O-ring on the vent screw so hopefully that was the source of water.
I will do as you say Alan and run it an hour or 2 then re-check the oil.

Which oil SHOULD i be using ? I have some EP80 w90 gear oil here ( automotive type ) is that fine to use for the time being while i check the engine and this water issue, or should i get marine grade stuff ?

i will grease all the nipples and bushings before starting it for the first time.

What would be a basic step by step starting procedure for the engine since we don't know its history ?


It is a merc 15hp ( not sure of exact year but id say late 80's early 90's )

Fresh fuel / oil mix ( 50:1 ) ?

Just a basic starting routine with regards to the choke setting, priming etc.. or anything else that i should be doing so as not to cause any damage

[Landlockedpirate]

Marine gear oil is designed to emulsify on contact with water and still give protection to the gearbox, automotive oil isnt.

Is your gearbox and your choice.

[spartacus]

Originally Posted by HighlandR

Which oil SHOULD i be using ? I have some EP80 w90 gear oil here ( automotive type ) is that fine to use for the time being while i check the engine and this water issue, or should i get marine grade stuff?

Automotive gear oil is okay temporarily, but I'd switch to Yamlube or Quicksilver for ultimate protection. Use new fibre washers for proper seal on drain and fill plugs.

Originally Posted by HighlandR

I will grease all the nipples and bushings before starting it for the first time

Grease nipple points until you see the old grease forced out. Wipe off excess.

Originally Posted by HighlandR

What would be a basic step by step starting procedure for the engine since we don't know its history?

Killcord in, fuel tank vented, choke out, fuel primer bulb hard, and tiller set to start. Ensure spark-plugs are in good condition, replace if unsure. Take up slack on pull cord, then pull. Might start first time. If it does, allow it to run briefly, then push in choke and reduce revs on tiller handle to idle.

Originally Posted by HighlandR

It is a merc 15hp (not sure of exact year but id say late 80's early 90's). Fresh fuel / oil mix (50:1)?

Use TWC3 2-stroke oil. 50:1 is fine.

Originally Posted by HighlandR

Just a basic starting routine with regards to the choke setting, priming etc.. or anything else that i should be doing so as not to cause any damage

Because you don't know history, look to replace water pump impeller, check condition of sacrificial anodes and renew starter rope. I'd also look at thermostat (renew gasket) if removing to clean.

[A1an]

^^^^^^

What he says

[Pikey Dave]

Remove the prop & check for fishing line around the prop shaft, re-grease the propshaft & re-fit the prop, repeat annually.

[eyespy999]

Hi. I had a 1989 variant of this engine that I bought second hand. Excellent engine. It has already been said but I dropped my gearbox oil refilled with quicksilver gearbox oil, new plugs and dropped the lower unit and replaced the impeller. It was my first outboard service and disconnecting the gear rod was the most difficult part of the process. Best of luck.

[HighlandR]

Thanks very much for the detailed replies guys!
It's amazing how much you can pick up and learn from just small bits of info from different people that helps to give a better overall view of things.

Spartacus thanks too for that reply
I followed each step by step ( other than replace spark plugs ) and tried to start but it wouldn't fire. Took the plugs out ( NGK BUHW ) they were pretty gummed up and black, so gave them a wet clean with some fine emery paper, put them back and it fired up on 2nd pull WOOHOO !!

Got it down to lowest idle soon as possible and left it like that, at first the tell tale was spouting water but then stopped after around 30 seconds. I believe these engines have a thermostat and the tell tale stops and starts as and when needed ?

I let the engine idle for around 2-3 mins but the tell tale never spouted anymore water - is this normal ?
Was starting to get worried incase the thermostat had maybe stuck and overheat the thing so i switched off, what duration roughly should there be between spouts ?

I wired the battery up to the starter motor to see if all was well but the starter will not power up.

Checked the switch with the multi-meter, traced the wiring back and the switch is working, there is also 12+ volt on the main supply cables and on the motor casing itself.

What should i check next ? anyone familiar with starter motor issues like this?

[Peter_C]

The tell tail should always be working. Mostly likely something is plugging it. You could try sucking on it, but blowing with an air gun gently is probably the best bet to clear it out. The tell tail is your way of knowing that the motor has water flow. If it stops flowing the motor needs to be shut down as soon as it is safe. Otherwise you risk damage to the motor.

Engage the ignition switch to the starter and gently rap on it with a hammer. Did it turn over? If you have 12 volts going to the starter, and it still doesn't work, other than a bad ground wire, you need to disassemble the starter and figure out why it is not working. Could just be corrosion, or the brushes may have failed. I doubt it needs replacement.