OMC Lower Unit grease

JTD · Jun 12, 2006

Hello, I have a 1984 Marlin with a 3.8 litere V-6 GM motor, V-6 OMC stern drive. Someone told me when I fill the lower unit grease that I am supposed to fill from the bottom, then from the middle to the top, if I don't then there will be an air bubble and the drive will burn up. I have always filled from the bottom up to the top plug of the lower unit just until the grease starts coming out the top. I fill the upper unit from the bottom plug hole and check the level with the dip stick. Is this correct? I am leaving on vacation in 5 days and now the=is person has me worried I am going to blow my stren drive up. Thanks for the help in advance.

KaGee · Jun 12, 2006

Re: OMC Lower Unit grease

Welcome to Iboats! You fill the lower unit of a Stringer drive from the bottom drain plug hole, until the oil comes out of the the vent plug hole(on the lower unit). To fill the upper unit, make sure the top plug with the dipstick is out. Fill from the bottom drain plug hole, until the oil reaches the "fill" mark on the dipstick. Do slowly, allowing time for air bubbles to work their way out. What I do is, when oil starts to overflow, I replace the bottom plug, let the unit sit for an hour or two and recheck the oil level with the dipstick. If more is needed I add from the dipstick hole. If it is overfilled I suck out the excess.

whywhyzed · Jun 12, 2006

Re: OMC Lower Unit grease

You have THREE seperate compartments to fill: The Lower Unit. The Upper Housing. The Intermediate housing. They are all sealed from each other, the advice you are getting is from someone not familiar with your 800 series srive. Yes, you fill each from the bottom just like an outboard's l/u

Purduebarry · Jun 12, 2006

Re: OMC Lower Unit grease

I've read that it's best to run the engine for a few minutes, engauge for a few seconds while still in the dock. Shut it down, wait a few minutes and check the dipstick. If it is improperly filled the air should make it's way to the dipstick, otherwise it appears full until you fry the drive. Search around on other threads, several have made this mistake. If you are unsure, double check. Hystat, do you agree this will reveal the problem if there is one?

JTD · Jun 12, 2006

Re: OMC Lower Unit grease

Thank you all for the quick reply, I also spoke to another mechanic and he said I was correct fill from the bottom up until it comes out the vent hole in the lower unit. Thanks again JTD

Boatin Bob · Jun 12, 2006

Re: OMC Lower Unit grease

The process you describe at the top is for an OMC Cobra not the stringer

Boatin Bob · Jun 12, 2006

Re: OMC Lower Unit grease

The process you describe at the top is for an OMC Cobra not the stringer

whywhyzed · Jun 12, 2006

Re: OMC Lower Unit grease

My fill plug is under water when the boat's in, so I dunno Barry. I usually am reassured by how many pumps it takes on my lube pump.

Purduebarry · Jun 13, 2006

Re: OMC Lower Unit grease

Okay, good point, should have said with muffs. Point is to run it and then recheck. Yes I have the OMC Cobra and JT probably has the stringer. Can you check them both using this method?

Purduebarry · Jun 13, 2006

Re: OMC Lower Unit grease

Just re-thinking this, others said to top off from the dipstick, that's not underwater? So if there is an air pocket and it migrates up then you'd be okay to top it off using this method. Bottom line is to not fry the gears, this is the worst situation, you think it's full and find out the hard way it's not. I know if you fill it right there should not be a problem, however until your sure of your methods isn't it better double check?

KaGee · Jun 13, 2006

Re: OMC Lower Unit grease

Stringer's and Cobra's are not to be confused. The advise above is for STRINGERS only. One assumes when you are changing the oil, you are doing so on dry ground.

OMC Lower Unit grease

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