gear oil in outflow or residual oil from sloppy service?

ShoalSurvivor

Petty Officer 1st Class
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Aug 1, 2012
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I just swapped my lower shifting cable, and changed the water pump while the lower unit was disassembled. I've performed this service multiple times and have been methodical and careful with assembly, using pins, and proper torque. I'm highly confident that everything was installed correctly. (including shift slide, water ring, gaskets...etc)

However, I forgot to drain the gear oil before servicing and made a huge mess inside the lower unit housing. I wiped everything up with dry towels, best I could, but there was certainly still film inside. I will NOT make that mistake again.

Today, I was warming her up in prep for an oil change. Startup was perfect, warmed up as usual, and water is flowing well from the outflows (using muffs). I have NOT shifted into gear or tested the shifting adjustments.

After a few minutes, I noticed that the outflow is not clear. it has a slight charcoal tint to it (mostly only visible as waves of water roll down the driveway). It also has a slight oil slick on top. I strongly suspend gear oil, but I don't know if its just cleaning out the housing, or if I biffed the service. I had topped off the remote gear oil tank, filled the outdrive to the top portal, and expected some additional fluid would be needed... but the remote is still at the full line.

I'd like to proceed with the oil change, because I already took it out of the garage to start up, and it's warm.. I think that's unrelated to my outflow problem, and I can just proceed and knock that out.


QUESTIONS:
1) any reason not to proceed with oil change, since its warmed up? (because I should NOT run the engine until the outflow is resolved?)
2) When would I expect the gear oil to fill into the lower unit from the remote fill tank? only after the lower unit is put into drive?
3) The plastic/rubber dam inside the lower unit is old (er). I doesn't look worse over last 6 years, but is old. Could that have failed?
4) If I soiled the inside of the housing in the void around the water pump housing, would that residue get burned off though exhaust heat?
5) Is this an obvious sign of the water tube not in place?
6) if I'm not in gear, and there is no other signs of a leak, is it ok to run for a while (how long?) to see if it gets "cleaned out"?

Thanks!!
Michael



original engine SN: L332123 replaced with: 2004 Mercruiser 4.3L 225hp 4bbl Quicksilver repower SN: 90004747 (#807736R11 / 03252004)
Alpha 1 Gen II - Transom: 0L517680 Drive: 0L192679 1.62 R (1.81R scratched on top) original drive may have been SN: L40356
 

harringtondav

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May 26, 2018
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2,438
The lube refill process is to pump lube from the bottom fill port until it dribbles from the upper vent. Close that vent and continue pumping until lube starts showing in the reservoir bottle. Then top it off. So reconnect your lube pump to the bottom fill port and pump more lube until the level raises in the reservoir.
Then:
1) No. Warm it again and proceed.
2) See above
3) This doesn't affect the sealed lube system
4) Eventually it will wash out. If your cooling system is working, it'll never get hot enough to burn anything.
5) No. If you are getting exhaust water from your muffs through the gimbal plate exhaust bypass ports, you're OK. Again, not related to the lube system.
6) You can run it for at least 1/2 hr, maybe more. Some on this forum advise against idling for long periods.

Once you get the lube bottle "burped full" you can engage the drive and monitor the lube level. One frequent 'Oops' in impeller replacement is omitting or displacing the small quad ring seal between the upper and lower hsg that seals the lube transfer passage. This will show with oil dribbling from that joint.
 
Last edited:

ShoalSurvivor

Petty Officer 1st Class
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Aug 1, 2012
Messages
217
Also, I peeked into the upper gear oil vent and found NO water. It dribbled out just like when I fillled it.
 

Bondo

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Messages
70,524
Also, I peeked into the upper gear oil vent and found NO water. It dribbled out just like when I fillled it.

Ayuh,..... Water is heavier than oil,........

I'm guessin' yer just seein' spilt oil,.....
 

Rick Stephens

Admiral
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Aug 13, 2013
Messages
6,118
Only way anyone can answer your real question is by pressure testing the drive. Anything else is just guessing. Proceeding with your service is what I would do if I didn't want to drain and test to make sure the seals were all 100%. If *your* best guess is left over residue, go to it. Keep an eye on your reservoir and go boating.
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,111
2) When would I expect the gear oil to fill into the lower unit from the remote fill tank? only after the lower unit is put into drive?

NEVER, you must fill the drive from the bottom plug until it comes out the top hole, then install the plug and pump slowly until you see it in the res bottle, then pour the gear oil into the bottle
 

ShoalSurvivor

Petty Officer 1st Class
Joined
Aug 1, 2012
Messages
217
2) When would I expect the gear oil to fill into the lower unit from the remote fill tank? only after the lower unit is put into drive?

NEVER, you must fill the drive from the bottom plug until it comes out the top hole, then install the plug and pump slowly until you see it in the res bottle, then pour the gear oil into the bottle

I did that. once that's done, isn't the point of the reservoir to monitor level for leaks?
 

ShoalSurvivor

Petty Officer 1st Class
Joined
Aug 1, 2012
Messages
217
Ayuh,..... Water is heavier than oil,........

I'm guessin' yer just seein' spilt oil,.....

I opened the bottom to fill per instructions above... and saw only gear lube. dunno if that tells me im out of the water, but I think my seals are all good.
 

harringtondav

Commander
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May 26, 2018
Messages
2,438
I did that. once that's done, isn't the point of the reservoir to monitor level for leaks?

Exactly. It may drop slightly after the first few times you use your boat after a refill. After that it's purpose is to indicate lube loss, and to prevent your drive from running out of lube.

A small amount of lube drop during a season is normal. The sealed lube system pressurizes when warm to force lube into the water thru any iffy seals. Then the check valve in the reservoir cap allows air back in when it cools vs. allowing water to suck back in thru the seals.
 
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