Water in oil? Should I be concerned?

[chriswjallen]

Hi everyone. Servicing my 2006 Mercury 15hp 2-stroke. I drained the gearbox oil and looks like this - is this water in the oil? Do I need to take to a specialist?

Appreciate any advice or views

Thanks, Chris

[Fenlander]

Others may differ but with a pragmatic approach I'd base my decision on... do you know when the oil was last replaced... how long ago if known... were the drain and filler seals replaced and if so with the correct material??

If the answer is no idea when last changed and/or not sure about filler/drain seals then I'd let it drain off out in the sun for ages. Fill with marine gear oil and replace seals with correct type. Then after next use drain or draw off a small sample and see how it looks remembering there will be some contamination from residual old oil.

Base your next move on what you find.

[chriswjallen]

Hi David,

Thanks for the swift response

The motor was last serviced in 2018 and the oil was changed then by a local outboard specialist. It’s probably only had circa 10 hours use since then!

I’ve bought a service kit and have today filled up with new oil and sealing washers.

I will do as you suggest David. Just wondered if the milky appearance was an immediate ‘red flag’, or perhaps the oil has deteriorated over the last 4 years?

Thanks again

Chris

[Fenlander]

Were the new sealing washers plastic or a fibre type? And same question re old ones?

[chriswjallen]

The new washers were a blue colour and felt like plastic.

Regarding the old ones, the top vent plug washer looked similar to the new ones, but the lower drain plug washer seemed really broken down and appeared to be black. The drain plug seemed loose and undid really easily too so maybe water had found it’s way in here?

[Fenlander]

My feeling is often towards a poor seal on the washers... in all the dozen or so older outboards I've owned never had to do the shaft seals just make sure these washers are OK. I commented on the type as some generic ones are quite hard plastic which needs a really firm nipping up to seal.

[chriswjallen]

Thanks and noted. I will drain some oil off after I’ve been out and take from there

[TmMorris]

I'd completely agree with Fen. There's water there but you won't at this point know where it has got in or when. On engines that aren't heavily used or abused I generally think that it's more common for ingress to be via a failure to put something back properly after a full strip down or an issue with the bleed screws.

If it was serviced 4 years ago and has been used for 10 hours since then you don't quite know if it's a tiny leak that has been letting in water for 10 hours or a sudden failure that's let it in recently.

Od flush it all out with any old cheap engine oil then refill with the proper oil, replace the seals on the two screws, use it for an hour or two and then just bleed some of the oil off to check and just keep checking it after each use.

I guess you could also pressure test it if you really wanted but that's not the milkiest of oil by the looks of ot so it doesn't look like it's a serious leak.

[jeffstevens763@g]

You could prove the shaft seals by pressurising the gearbox but does sound like drain plug washers

[chriswjallen]

Thanks for the responses.

I decided to strip it down to replace the impeller - glad I did because there was silicone sealant in there which suggests a bodge job from the ‘professional’ who supposedly changed the impeller 4 years ago - or he simply didn’t bother but charged me for the privilege! . Given minimal use, the impeller didn’t look too clever either. See photos.

I’ve cleaned it all up and will buy a service kit to replace the seals, impeller etc and hopefully this will fix the water ingress!!! Found some really good videos on YouTube talking through it all step by step

Chris

[TmMorris]

Silicone sealant or lubricant? If the latter it's meant to be there.

[chriswjallen]

Silicone sealant similar to that used in a bathroom. I had to scrape and peel it off with a flat head screwdriver!