Mercruiser Alpha One Gear Oil Milky and Pressurized.

[Smokey988]

Hello all,

I just recently purchased a 2007 Four Winns H183 Fish and Ski with 214 hours on it and have been checking all the fluids before every trip out and all fluids had good color and levels.
Today I noticed a small oil slick when loading the boat back on the trailer so I decided to check all the fluids again. When I removed the fill vent on the sterndrive I was shocked to see white oil (watery oil) come out. I went to check the Gear Lube Monitor mounted on the Merc 4.3 and it was full and bulging with pressure. When I released the cap fluid came out and spilled over into the bilge.

I immediately drained the gear oil from the lower unit as well as the Gear lube Monitor and did a quick pressure test. I only went to about 8lbs but it did not drop at all after 10 minutes.

What am I missing? Would a leak not have to be present for that amount of water to get into the sterndrive? And I am 100% sure the gear oil was in good condition prior to today's trip out.

I appreciate any input.

Thanks

 

[achris]

Hello and :welcome: to iboats.

A pressure test only tests the drive seals ability to keep oil in, not keep water out. To check the water seals, you need to do a vacuum test... Also be aware that some seals may hold static, but can open up dynamically. And I've also see seals leak at very low pressure (1 or 2 psi) then seal up again under more pressure...

Being 12 years old, I'd 'shotgun' the drive. Pull it completely apart and re-seal the whole thing. Look at the seal surfaces too...

Chris.......

 

[Smokey988]

Hello and :welcome: to iboats.

A pressure test only tests the drive seals ability to keep oil in, not keep water out. To check the water seals, you need to do a vacuum test... Also be aware that some seals may hold static, but can open up dynamically. And I've also see seals leak at very low pressure (1 or 2 psi) then seal up again under more pressure...

Being 12 years old, I'd 'shotgun' the drive. Pull it completely apart and re-seal the whole thing. Look at the seal surfaces too...

Chris.......

In 2018 it had the upper redone with U-Joints, Socket, Yoke, seal kit along with the impeller. I guess I am just baffled by how much pressure the Gear Lube monitor was under, for that mater the vent to when I unscrewed that.

 

[Rick Stephens]

Possible to have a seal issue under the water pump that allowed pump to force water in? Seems a likely possibility.

 

[Smokey988]

Possible to have a seal issue under the water pump that allowed pump to force water in? Seems a likely possibility.

That is kind of what I was thinking. I was not sure if this was possible or not. Is it possible? May be a good idea to just drop lower unit and change impeller, housing and gaskets, fill with new oil and see what happens.

 

[achris]

In 2018 it had the upper redone with U-Joints, Socket, Yoke, seal kit along with the impeller. ....

With this new information.... You have 4 seals left. Shift shaft seal, drive shaft seal (under the water pump) and the bearing carrier seals (2 on the prop shaft) and 'O' ring. Given that the shift shaft seal and the drive shaft seal are known to leak, I'd hit those immediately.

The oil bottle cap has a one way vent (that little rubber flap in the cap). It lets air in, but not out, that's why you got a pressure build up.

Chris.......

 

[Smokey988]

With this new information.... You have 4 seals left. Shift shaft seal, drive shaft seal (under the water pump) and the bearing carrier seals (2 on the prop shaft) and 'O' ring. Given that the shift shaft seal and the drive shaft seal are known to leak, I'd hit those immediately.

The oil bottle cap has a one way vent (that little rubber flap in the cap). It lets air in, but not out, that's why you got a pressure build up.

Chris.......

So I did a little more testing today and here are the results. I did a pressure test at 2psi and it held 5 minutes no problem, 7psi and it held 5 minutes, 12 psi and it held for 30 min, . I moved to a vacuum test and and it would go up to 5 in hg and drop down to 3 in hg quick and slowly down to 1 or 2 in hg and finally 0 after a few minutes.

I also received further service records and the prop shaft seals were changed last fall due to fish line damaging the seal.

I have read mixed information on the forum here as the whether a vacuum test will actually work on the Alpha 1 Gen 2. Any insight into this?

 

[achris]

I service quite a few gen 2s, vacuum test works fine. Why wouldn't it? Still have to stop water getting in....

 

[Smokey988]

I service quite a few gen 2s, vacuum test works fine. Why wouldn't it? Still have to stop water getting in....

Thanks Chris. I guess off comes the lower unit.

 

[Smokey988]

I removed the lower unit and held a finger over the oil passage and both pressure and vacuum test were good. Does this mean I should be looking at the upper unit?

 

[Smokey988]

Also milky oil in speedometer hose, is it normal to have any oil in speedo tubing?

 

[achris]

The only place the speedo pickup comes close to the gear oil is at the front of the drive, right next to the shift shaft seal....

Chris.........

Exploded diagram of the shift shaft seal carrier. The top of #39 is the speedo feed. O rings #37 are very close together...