Gear Oil

Hi,<br /><br />this about an OMC 3.0 sterndrive from 1988 mounted in a bayliner capri<br />I want to change my lower gear oil but wich fill plug should i use.<br />Normally it is the lowest plug but i have been told that one should use the upper plug when you fill a OMC Cobra drive.<br />Sorry fot my bad english I am Dutch.<br /><br />arnold

Re: Gear Oil

Arnold ,<br /> You want to drain from the bottom plug,pull the middle plug,pull the dipstick. Install bottom plug, fill from middle plug,when you have the 60 oz of fluid in , put the dipstick in then undo your fill tube from the middle plug.

Re: Gear Oil

Welcome to iboats and your English is fine.<br /><br />The way I was told is fill it from the bottom until it comes out the middle. Then plug the bottom and continue filling from the middle until it reads full on the dipstick. With the right light, you can look down the dipstick hole and see a shaft. Once the lube covers the shaft, then start checking the level on the dipstick.<br /><br />Frankly I fill it from the bottom until it comes out the middle and plug the middle. Then I continue filling from the bottom. Haven't lost one that way yet.

Re: Gear Oil

Willys way might work just fine. I took the above method direct from the factory service manual. <br /> What ever you do , make sure you get the required 60 oz of fluid in the unit. If you don't you'll be buying a new set of upper case gears for sure.<br /> And like Willy said welcome to Iboats!

Re: Gear Oil

fill from the bottom. when it comes out the level plug, wait, dont keep filling. after a minute or 2 check your dipstick, you will notice the level rose. the gallery they give for the dipstick is small and the oil viscosity prevents it from getting there quickly. if you overfill you will blow oil out your input shaft seal into your bellows.

Re: Gear Oil

Hi Guy's <br /><br />Thank's all for your quik response.<br /><br />I think i get the point, so do I understand it right that when fou fill up your lower gear case you will also fill up the upper gear case.<br />And where is the dipstick is that perhaps the big " chrome" nut wich you can see when you look at yout sterndrive from the boat (in the middle of the top of the upper drive).<br />I have a simple drawing from the stern drive the upper gear housing, is it the (60) oil indicator screw <br /><br />Greetings,<br />Arnold

Re: Gear Oil

As RedRanger said, the manual specifies that you drain from the bottom plug and fill from the middle plug. But I think he may have put where you pull the dipstick out of order.<br /><br />Place the drive in the down position. <br /><br />Remove the bottom (drain) plug and dipstick to drain (yes, sounds like you're refering to the correct place to access the dipstick). After oil has drained completely, replace oil drain plug and tighten securely.<br /><br />Remove the fill (middle) plug, and fill until the oil level appears at the mark on the dipstick. Check oil level with dipstick cap resting on top of the hole. <br /><br />Securely replace the dipstick before removing the filler from the gearcase. This will create an air lock and will hold the oil in the verticle drive until the oil fill plug can be securely replaced. <br /><br />Don't know that there would be any problem with filling from the bottom until it reaches the fill plug and then switching to the fill plug and filling the rest of the way from there, but it would be an extra step. <br /><br />What I do know is that you shouldn't just fill completely from the bottom drain plug!!! The following statement is from OMC: <br /> <br /> When filling the Cobra with gear lube, use the middle fill plug, as shown in the Owners' Manual. Do not fill through the (bottom) drain plug! If you fill from the wrong port, you will probably trap a big bubble of air inside the vertical drive, and that bubble will eventually rise to the top. When it does, the upper gearcase gears will run dry, and self-destruct. <br /><br /><br />Either way, suggest if it's the first time you're doing this you check the fill level before you drain to make sure it's full, then measure the amount of oil you've drained and compare that to how much it takes to account for any possible air pockets. <br /><br />On my '89 4.3L the specs call for 64 oz.