Oil Leak Around Top Overflow Screw

[trb1607ze]

Bought one of your 90-206-B20 units on June 2 as the old one on my '89 Mariner was toast. Got the unit installed and for the first time got to use it this past 4th of July weekend. I'm up to ~4 hours on the 5 hour initial break-in time. Every time I ran the engine, when I got back to the dock, I would get in the water, go to the back of the boat and raise the unit out and visually inspect. Each time, there was pretty much nothing to see and the lower unit worked great - no shifting problems, etc.

When I finally trailored the boat simply easing over from the dock to the boat ramp, after I got to the top of the ramp to put on the boat straps, I noticed foot oil running out of the top oil overflow screw. I took a screwdriver and the screw was tight, but it continued to leak oil for several minutes.

My question here is can you send me a replacement top oil screw, or give me some info/a recommendation on what I should do? I assume the O-ring is not sealing properly as the screw is tight.

Also, now that I've seen leaking around this screw, would you also now recommend changing the foot oil? I suppose a leak could go the other way and get water in gear case - not good. I can say that raising the unit out of the water after each run for visual inspection, I did not notice any oil leaks - it would been apparent and not sure what would have caused to all of a sudden start

[admin]

I am sorry you are having an issue with the drive. I would guess that when the oil was heated up from running, it would create enough pressure to leak. I suggest removing the plug and inspecting the sealing surface in the case. It is possible that there is a small chunk of paint or some foreign material which is not allowing it to seal properly. If so, you can scrape it out with a small flat blade screwdriver or other suitable tool. You can also inspect the gasket to see if there are any imperfections in it, and if necessary you may call us to send you one, or you can also pick one up at any marine dealer.

I would definately recommend changing the oil as well.

Tech Support

[trb1607ze]

Will Mercury/Mariner oil fill/vent screws fit?

I've still got bad Mariner lower unit and it still has the oil fill/vent screws. Will they fit this unit. I know these never leaked.....Just a thought.

[admin]

Yes they will fit, but I think there is something causing the plug and gasket not to seal, so inspect is as I mentioned before.

Tech Support

[trb1607ze]

Checked it this past weekend....

This past Sunday, I checked the overflow as mentioned. There really wasn't any trash or foreign debris that I could see. Being a mechanical engineer, what I did see were the threads are not very good. It's like whoever tapped the hole used a dull tap - threads are sort of rounded and not sharp, although the screw will tighten okay. The overflow screw was not put in cross-threaded by me - that's a fact. So, I took a 3/8-16 tap and turned by hand only (no wrenches) to try and clean them up - it seemed to help. Here's my plan to seal.

I'm going to take a Mercury screw, which I believe is slightly longer than the supplied screw. To that I am going to add an O-ring to the already compacted cork type seal already there. On top of that, I am going to add some plumbing teflon tape to the threads. And put the screw in. Hopefully this will work.

Next time I run it, I'll check for outwards leaks. No way tell on inward leaks (water getting in) unless you change the foot oil, which I will do subsequent to next time out. I will keep you notified if the leak persists and see where we need to go....

[trb1607ze]

Any additional thoughts about my post above?

Will be taking boat out next weekend. Any additional tips to try or thoughts regarding my last post above?

[admin]

I am not sure the extra steps would be necessary. It may actually cause more of an issue. I know if you use two of the OE style gaskets it will usually leak. One gasket with clean surfaces on the case and plug should do the trick.

Tech support