You can temporarily use a 3/8 in adjustable bait well plug made by MOELLER.

Interesting. It appears the threads are bad in the tank(of course!) and not on the cap. Cap threads & o-ring appear perfect. Today I leveled the motor and filled the tank completely full(still see a small air bubble on top but thinking that’s not a problem) and put the cap back on w/Teflon plumbers tape on threads. Hoping that’s going to hold. Plan on fishing Thurs or Friday and then I’ll be able to see if it leaks. I’ll give it a try if my “fix” didn’t work. Thanks for the info! Neil

THIS little trick has saved me before…and lasted few months until my new tank came in

Yes, that is what I was talking about using on the tank to fix a leak BUT DON’T use that on the cap. 5200 is permanent and you would not get the cap off without destroying it.

This is great news as a backup to my “repair” if it didn’t work but one more question: the threaded cap screws inside(or into) the threaded neck of the oil reservoir. How does the Moeller 3/8 adjustable bait well plug completely seal and not leak because of the inside threads of filler? Thank You, Neil.

Along with fitting tight against the top of the tank, the rubber conforms to the threads and seals.

Interesting, never heard of this. The sender went out in my tank and I jumped it until I can replace. I was going to post on the aftermarket versus Merc tanks until I saw this thread. After reading the whole thread I never saw an answer to the ?. Looks like I will be taking it to a shop which I was planning to do anyway because I need some diagnostic work on my warning horn.

Take a paper clip and cut it off and push it in the connector for the warning horn wire….no more horn

A fuse works too

The tank is leaking? Or its coming from where you screw the cap on?

If its the cap use some thread sealer tape on the cap and then tighten in back.

Good info. I need help with a different issue. I have already replaced the little tank a few months ago.
The alarm went off today and I discovered the tank was about an inch low. I removed the cap cranked the engine and it did not fill. I filled the tank by hand and placed cap back on and it ran fine with no alarm...HOWEVER, I checked the tank and it is down a little.

How long did you run the motor? It usually will fill up fairly quickly but it can sometimes take a while if there is any air in the line in the tank located in the battery compartment. The engine mounted tank will drop some if you do not bleed 100% of the air out. That’s why it’s best to tilt your motor AND turn the steering wheel until the “air pocket” is directly below the cap. Once you crank the motor and oil starts coming out the hole, then you can replace the cap & there should be no air in the tank. Hopefully you didn’t get any air In the line when you changed the tank. Just a small amount of air means no oil will be mixing with gas for a period which in turn means no lubrication in the cylinder. This is one reason powerheads will blow. This is why it is recommended for a shop to perform an Oil Pump Prime Sequence while it’s hooked up to their computer. That forces oil through the lines so there are no air pockets.

Thanks Mike, I will take it in. Do you think since my engine mounted tank level dropped I have an “air “ problem or maybe a pump issue.

Couple things you can check. Make sure the remote (boat) tank is not filled over 75% and the cap is on tight. You need air space in the tank so it can build pressure and force oil to the reserve (engine) tank. You can spray soapy water around the connections to on the remote tank with the engine running to see if there's an air leak anywhere.

I don’t think you have a pump issue since your engine tank level is dropping even though it shouldn’t drop at all. Since it’s dropping you can the pump is actually working. The only time the engine tank should go down is if the remote tank is empty or you get air in the line from the remote tank.

Definitely do what Bryanmc57 suggests. It’s a very good suggestion which should help you isolate where any air may be coming from. Also check your engine tank just in case it may have an issue.

Another thing that can cause air in the line is when the level gets really low in the remote tank. If your in rough water when it’s low, the oil will slosh around a lot and the pickup tube may catch air pockets multiple times which will allow air to get in the line. Once that air pocket hits your engine tank, that tank will go done some. Like I mentioned previously, if you do NOT get the engine mounted tank 100% bled, the level will drop some too.

Those engine mounted caps are notorious for stripping the tank if you over tighten them. I took a dremel and etched a small mark on the cap and the tank. I always tighten the cap until the marks line up so I always know it’s just right.