Alpha 1 Gen 2 - gear oil reservoir purge question

[KHE]

I recently changed the water pump impeller in my lower unit and re-filled the gearcase with the Mercruiser High Performance gear oil from the bottom plug until the oil came out the upper vent plug hole.

I am ready to install the drive on the boat. A couple of days ago, I drained the reservoir and wiped it out, then cleaned it. The Mercruiser shop manual states that after filling the drive from the bottom, to open the vent plug, then fill the reservoir until the oil comes out the vent hole, then fill the reservoir to the full line, then monitor the level.

Since the drive is currently off, what about placing the drive on its side, filling the cavity through the vent plug, installing the drive, then fill the reservoir to the full line? Seems like that would minimize any air in the system.

 

[KHE]

A couple of days ago, I installed the drive (oil level at the vent plug from when I did the water pump impeller), then followed the Mercruiser procedure - filled the oil reservoir to the full line, then removed the vent plug. The gear oil was already flowing out the hole so I reinstalled the plug and filled the reservoir to the full mark. I started the engine on hose muffs, shifting into forward and reverse a couple of times to test everything and then shut it down. The gear oil level was still at the full mark on the reservoir.

Yesterday, I launched the boat and cruised around for an hour and checked the gear oil, expecting it to have dropped but it was about 1/4" above the full line. There was not any water in it. I'll check it again the next time I use the boat and if it has stabilized, I'll remove some of the oil to bring it back to the full line. It just seems odd that the level would have increased.

 

[Scott06]

I think the oil expands as it warms up, if you let it cool off I bet it will come back to its original level.

 

[SCORPIO]

+1 on what Scott06 said. Also, it may take several outings for the fluid level to stabilize as the air in the line and drive purges. Keep an eye on the bottle.

 

[KHE]

Thanks for the suggestions. I'll keep an eye on the reservoir.

 

[Strecker25]

regarding your initial question about filling on its side..that's what I do. It usually makes it so I never get a drop at the reservoir. Prior to doing that I would usually have to top it off a couple times in the beginning of the season

 

[Bt Doctur]

The reason you fill from the bottom is to displace the air. failure to do so will result in drive failure.Once it comes out the top vent , install the vent.put in 2 or 3 more gentle p[umps and it enters the bottle, now fill from the bottle.

 

[KHE]

I filled it from the bottom - I replaced the water pump impeller over the winter when the boat was in storage and the drive was on the stand in the basement. I checked the reservoir this evening and it was about 3/16" below the full line so I added some oil to bring it back to the full mark. I followed the Mercruiser procedure to the letter - it sounds like I'll need to monitor it for a few runs.