Water and Tiny Filings in lower unit of 1991 4.3 Cobra

[Ski Bob]

Thank you for reading. I have a 1991 Four Winns 4.3 Cobra and just changed the lower unit grease mid-season to be safe. It is a 64 Ounce fill. When I had filled it before, I put in 64 ounces as well. I noticed after filling I DID NOT use the synthetic I usually use so after one hour on muffs and TWO HOURS on the lake I drained it out.

After draining the lower unit I noticed a SMALL amount of water when it first started draining, you know, the milky look for about 1/2 cup and then the rest looked like the new stuff it was. So, I've owned the boat since new and have NEVER replaced any seals in the lower unit. Is it just a seal behind the prop? Easy to replace? Do I need the shop manual to do it or is straight forward?

Secondly, I noticed a SMALL amount of metal filings on the drain plug magnet. And I mean a SMALL amount. Is this normal for this age of boat or is something going to let go?

Lastly, I was always using Johnson/Evinrude synthetic 80-90 gear oil until I bought the wrong stuff. So, drained it out but they did not have my usual. So, because of the potential water, I purchased AmsOil Synthetic and it says exactly on bottle- 75W/80W-90 gear oil synthetic and exceptional for water contamination up to 10%. So, due to the potential water issue, I bought that because I want to lake test this thing again in the morning. So, I will be on the lake by 10 AM Central time hoping all runs well.

So, oil recommendation, metal filings on drain plug magnet and water in oil so I need to replace WHAT seal and is it a nightmare?

Thanks folks, you are a dandy bunch. Bob

 

[Boomyal]

Re: Water and Tiny Filings in lower unit of 1991 4.3 Cobra

I use the Amsoil in all three chambers of my stringer outdrive. The rear end in my E150 1/2 ton requires synthetic so I use it there as well. Great stuff.

A tiny amount of metal filings are not necessarily unusual. That is why they put the magnet on the plug. Just keep on eye on it, even if you don't do a full drain.

You need to pressure test your drive. Not sure on the cobra but probably about 14 psi should hold for quite a spell. Have a spray bottle with a soapy solution in it to test around the prop shaft and the propshaft carrier. If you see no bubbles there, listen carefully between the drives. It could be leaking there. You may have to remove the lower and test all around the top of the lower drive. Then take it from there. Not sure on any reseal procedure for your drive.

 

[Ski Bob]

Re: Water and Tiny Filings in lower unit of 1991 4.3 Cobra

Thank you for your reply. I took it out today and ran half tank of gas through it, about 20 gallons and was on the water for about four hours. Ran great. Came home and slowly opened the top dip stick cap and heard it hiss so there was pressure in the drive. I opened the bottom drain slowly and drained a small amount of grease. It appears that it may have a tiny bit of water. I am going to wait a day because I believe water is heavier than the grease so if I begin to drain the drive two days from now, the water should drain first? Then I will have an idea as to how much water I am taking on? Thanks for your reply.

 

[bonzoscott]

Re: Water and Tiny Filings in lower unit of 1991 4.3 Cobra

So, I've owned the boat since new and have NEVER replaced any seals in the lower unit.

Quite possibly your drain/fill/vent plug seals (plastic washers on the plugs). I wouldn't sweat 1/2 cup of water at this point. I think you're drain seal is leaking. The entire contents / lube would be thoroughly mixed from top to bottom if it were a bad leak. And it would take weeks to separate. I always use OMC premium blend and I always have the hiss from dip stick. Odd design - pressures in the case cavities, I don't know. If it were me, I would make sure I change lube along with plug seals, including dip stick seal for the winter and take a look next year.

 

[Ski Bob]

Re: Water and Tiny Filings in lower unit of 1991 4.3 Cobra

Thank you sir. I appreciate your advice and will take it. Have a nice evening. Bob

 

[jerryjerry05]

Re: Water and Tiny Filings in lower unit of 1991 4.3 Cobra

You need to change the drain plug seals on the unit everytime if they are the plastic ones.
I change the OMC's to the Merc drain seals,they are felt and can be use again and again.
I always replace them anyway on every change.
If the water was the first thing that came out??
I'd bet it's from the seal around the screw.
A tiny bit of shavings, ok.
Amsol is the best!!

 

[Ski Bob]

Re: Water and Tiny Filings in lower unit of 1991 4.3 Cobra

Ok, I appreciate your response too! Man, you guys are sharp. Anyway, the drain plug and vent plug are metal and are identical and both have a maganet and a rubber O ring on them. And, no, I have NEVER replaced them. They are original from 1991. Anyway, regarding the FIRST thing that came out, yes the milky water was first for about 1/2 to 1 cup worth and the rest of the grease was, well, looked straight out of the new bottle. As said earlier, when I opened the top dip stick cap I heard a hiss so obviously there is pressure in the drive and it must not LEAK a bunch. Thanks. Bob

 

[bonzoscott]

Re: Water and Tiny Filings in lower unit of 1991 4.3 Cobra

I'm not aware of any kind of "Metal Seals". Maybe someone else here can verify but that seems to me the problem. I have a '90 cobra and they are plastic washers. They last many seasons with 1/8 turn past seat. Has anyone or shop ever serviced the drive? I don't think that's right. Unless maybe OMC switched at some point.

 

[Ski Bob]

Re: Water and Tiny Filings in lower unit of 1991 4.3 Cobra

I apologize! I am NOT the wizard of these things. I meant that the drain plugs themselves are metal. So, I need schooling on what SEALS we are referring to. I was thinking that the actual drain and vent plug with the rubber O-ring on them is what we are referring to that are removed tro drain the drive. sorry. Keep me out of the woods. Get lost quickly! Snipe hunting anyone?

 

[bonzoscott]

Re: Water and Tiny Filings in lower unit of 1991 4.3 Cobra

No apology necessary. I went to the BRP site: http://shop2.evinrude.com/Index.aspx?s1=a3pnhs66lvvub9kan6lt3du724&catalog_id=0&siteid=1
Find your motor - look at parts 53 & 54 on lower gear case. Part 54 reads washer (#0333572). Then when I google that number, all the aftermarket places reads "O-ring". So I think either one will work but I think the plastic washer is best. BRP is where I got mine and they are the same on my outboards too.