Oops - Engine run with very little gear oil

[CUSAC]

A bit of a watch it/cautionary tale for anyone putting a used engine on their boat.

It was time to service the new to us 2015 Mariner 150hp 4 stroke. Bought it with 1200 hours on. It was previously on an MOD boat and had been removed and put on engine pallet. It had a 300 hour service about 5 running hours before it was removed. Engine oil was drained to avoid leaks. We then paid someone to rig it on the boat. They added new engine oil and prepped it ready to go and test ran it on muffs.

110 hours of perfect running later it was time to service the engine. Engine oil replaced. It looked a little black but nothing serious. Then went to do the lower unit oil. Removed fill plug and just a little dribble. Fine I thought, still the vent plug to go. Vent plug removed and barely any more oil came out. Probably 100ml max compared to the 780ml expected.

The oil that came out was black but no sign of any metal shards in it. No milky oil and no water, which suggests the seals aren't leaking. Also I haven't noticed any oil leaking onto the floor where the boat is stored.

The only conclusion I can come to is that the gear oil was also drained when it was removed from the last boat and was never checked or topped up when it was rigged. I can understand why they would drain engine oil to lay it down but wouldn't have thought it was standard practice to also drain gearbox. I should have checked all the fluid levels in hindsight to double check the mechanic had sorted engine oil, gear oil and trim fluid.

I haven't had any issues shifting or with the performance. Should I buy a lottery ticket as I have been unbelievably lucky, or is it likely permanent damage has been done? It would have had a little oil splashing around, but nowhere near the specification. My current plan is to run it for another 10 hours with the fresh oil and then do another change and hope for the best.

[Matt]

Outboard engine gearboxes are fairly simple beasts, unlike, for example, a bravo drive which can blow a top end quite easily without enough oil (it uses the oil to cool the top end bearings & gears)

Certainly won't have done it any favours, but I'd do as you suggest and short change the oil - if there's no glitter in it and the seals survived, personally I'd just carry on as normal. The propshaft gears will have picked up what was there up and splattered it around, so you might have got away with it. The bearings are likely OK, but could have worn the thrust washers.

[Voodoo]

As above.....and don't bother with a lottery ticket, you have already won once.... :-)

[Matt]

One of my friends did actually blow up a bravo drive once. He drained the oil out, but then didn't refill it correctly (ie from the bottom up).

First indication we had of this was when the engine hit the rev limiter and we lost all drive. At first we thought the propshaft had sheared, but nope, prop still there & spinning. He sold it on as spares, so I never saw the innerds, but apparently it was the sleeve that joins the upper and lower driveshafts together that failed. A surprise - I was expecting the casing to just be full of grinding paste and nothing else, but by all accounts it was repairable. And that boat had been running all day at WOT with no oil when it let go.

He also forgot to tighten the 1 1/16" raw water inlet hose when he changed the impeller, so that had blown off earlier in the day. Quite a bit of urgency to reattach that - the water was coming in quickly. While he was under the hatch (and suspiciously knew where to look for the leak immediately!!!) I was lining us up to the nearest shoreline ready to do a rapid approach onto the mud bank before we got too much water on board.

I don't let him touch my stuff. You can see why. But because he's a mate, he can remain anonymous.