Oil sheen in water after start up

[Monterey296Twin5.0Gi]

We have twin 5.0 Gi motors (PBYCCE) and SX-M outdrives, 1998 vintage. We just had a major 'haul out' overhaul on both SX-M outdrives, fully cleaned and serviced, new bellows and gimbal bearings, and U-joints, and seals, gaskets, and lower seals. Then we had them painted with Interlux antifoul paint. They pressure tested both drives.

We have only driven it once at full speed since it went back in the water. They performed great and we didn't notice anything obviously wrong or any oil or sheen on the water. We went to take the boat out for the second time and on start-up we saw that both outdrives were casting this oil sheen onto the water surface seemingly from the exhaust. It seems to bubble up from underwater at or near the prop, but also seemed to billow out of the gimbal housing closer to the transom as some exhaust bubbles up there too (now that things are all clean of marine growth). I assumed the worst that it could be gear oil, but many posts seem to point to it being fuel. Both engines seemed to start and idle normally, so it didn't seem to be a rich fuel problem if that would cause a rough idle. Engines were cold and it was coldish for California. We took the boat out and we didn't see the problem again after idling in neutral and shutting down and starting back up.

Any input is appreciated. We do not think it is the trim cylinders since we don't operate those in the slip.

Here is a movie showing it bubble up and then it continuing to billow out even after we shut the engines off.

New video by Tim Noble

photos.app.goo.gl

 

[alldodge]

That's a pretty good leak. Check the motor oil level and power steering. If their good, then need to get the drives checked

 

[Lou C]

A leak like that would get you cited by the Coast Guard here! Check all fluids and see what's low, could be power steering (cooler) or internal oil leaks in one of the engines (you'd probably see milky motor oil then). Do the engines have engine oil coolers?
You say that the oil seems to be coming from the prop and the transom mount, that's where the exhaust water exits in both cases, so I'd be checking engine oil and p/s fluid for low levels and milkyness.

 

[harringtondav]

I'm just learning VP drives. My new SX's trim motor/reservoir is mounted outside of the transom, in the water, on the starboard side tucked up between the drive and gimbal ring.
....another source of oil in water.

 

[Lou C]

The SX-M drives that the OP has, have the trim pumps inside like the Merc drives and OMC Cobra. The first couple of years of the SX-A drives they did have trouble with the external trim pump

 

[Monterey296Twin5.0Gi]

Thank you for the replies. I am hesitant to think it is any oil from the engines since we only had the outdrives serviced, but I did check the dip sticks and they were not milky. I will recheck the oil level when I return to the boat. It did look a little low on both, but I assumed it hadn't drained back to the pan yet after our run.

One thing we did notice is that when the engines were off I put the Port engine in the on position, so fuel pump was energized, and it seemed to billow out a cloud of sheen before even cranking it over. It could have been a coincidence that it just burped out a bubble in the exhaust bellow.

When I stuck my finger in the water surface it smelled a bit like older gear oil, even though our gear lube was just changed I assume it smells similarly after being in the outdrive. What seems odd to me is that both I/O's had the problem and the common thread in both was our mechanic or the parts he used. What is also odd is that the problem seemed to go away, as if there was a break-in period or the seals were cold and didn't seal well. The main difference this time between when we first tested the boat after repairs was the film of bio-slime on the drive from sitting a couple weeks.

When I go back out I will test the trim cylinders before I start the engines and run both up/down to see if we see any oil. Then one at a time I will turn the key on and look for any sign of oil and start each and look again. I may try and get a camera down there to see if there is obvious leakage at the lower unit. Out trim cylinder pumps are just inside the transom on boths sides as seen in pic below:

 

[bruceb58]

I had that problem on the boat I just sold. Was a leaking engine oil cooler. Look at your engine oil level carefully. I almost ran my engine out of oil.

Not sure if your engine even has one.

 

[cptbill]

We have twin 5.0 Gi motors (PBYCCE) and SX-M outdrives, 1998 vintage. We just had a major 'haul out' overhaul on both SX-M outdrives, fully cleaned and serviced, new bellows and gimbal bearings, and U-joints, and seals, gaskets, and lower seals. Then we had them painted with Interlux antifoul paint. They pressure tested both drives.

We have only driven it once at full speed since it went back in the water. They performed great and we didn't notice anything obviously wrong or any oil or sheen on the water. We went to take the boat out for the second time and on start-up we saw that both outdrives were casting this oil sheen onto the water surface seemingly from the exhaust. It seems to bubble up from underwater at or near the prop, but also seemed to billow out of the gimbal housing closer to the transom as some exhaust bubbles up there too (now that things are all clean of marine growth). I assumed the worst that it could be gear oil, but many posts seem to point to it being fuel. Both engines seemed to start and idle normally, so it didn't seem to be a rich fuel problem if that would cause a rough idle. Engines were cold and it was coldish for California. We took the boat out and we didn't see the problem again after idling in neutral and shutting down and starting back up.

Any input is appreciated. We do not think it is the trim cylinders since we don't operate those in the slip.

Here is a movie showing it bubble up and then it continuing to billow out even after we shut the engines off.

New video by Tim Noble

photos.app.goo.gl

View attachment 352550

You don't have to operate the trim units for them to leak

 

[Lou C]

I did have a similar issue with trim lines leaking because of cuts by barnacles but it wasn’t nearly that much oil in the water.

 

[Nheels]

Could be fuel from a stuck injector. Change the plugs recently?

 

[Monterey296Twin5.0Gi]

Could be fuel from a stuck injector. Change the plugs recently?

We haven't checked the plugs, we just had both outdrives serviced. It seemed to come from both outdrives/engines, so that leads me to believe it may not be a stuck injector on both engines. Also both engines started and idled very smoothly. We have the mechanic coming to look.