4-Beep Oil(?) Alarm

**David - WI** · 07-26-2025, 01:04 PM

If it was the check valve, I would think the tank would leak down further when it sat longer?
With the crack in the tank it only leaked down to the crack, regardless of long it sat.

**skialot2** · 07-26-2025, 01:27 PM

Originally Posted by Basnova

I remember at the dealership when I bought it in 1998 that they said not to touch the engine tank cap because it needs to be tight and you don't want to tear the gasket. When you fill oil, fill the remote tank. So, that's what I've done over the years. I had it professionally serving e for many years, but sure if they ever loosened that cap. So, I am very concerned about loosing it if it hasn't been opened in all these years, and that it's so tight I might ruin the gasket. If that happens where do I get a replacement gasket? No one wants to service my engine near me, and parts seem to be far and few between out here. Can I make a gasket out of something, if need be? Of course, all this is moot until I look at it today or tomorrow.

I think it's a rubber gasket. It should be fine. But if not, the gasket part number is 27-42999T It is available just about anywhere. I like the parts catalog at Mercurymarine.com it gives you all the superseded part numbers too.

Amazon.com: Jetunit 27-42999T Oil Tank O-RING for Mercury Mariner Outboard Oil Reservoir Level Cap Gasket 25-11332 Sportjet 105/135/140/150/175/200/225/250/275HP DFI EFI JET : Automotive

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**XstreamVking** · 07-26-2025, 02:03 PM

Could be several things. Got to give it a good check visually for oil leaks. Follow the lines etc.

**Basnova** · 07-27-2025, 09:50 AM

Originally Posted by skialot2

I think it's a rubber gasket. It should be fine. But if not, the gasket part number is 27-42999T It is available just about anywhere. I like the parts catalog at Mercurymarine.com it gives you all the superseded part numbers too.

Amazon.com: Jetunit 27-42999T Oil Tank O-RING for Mercury Mariner Outboard Oil Reservoir Level Cap Gasket 25-11332 Sportjet 105/135/140/150/175/200/225/250/275HP DFI EFI JET : Automotive

This is all excellent information for me. Thank you. Just so I know, looks like there is no screen or filter on the remote tank pickup hose, correct?

**Basnova** · 07-27-2025, 10:01 AM

I'm going to be looking at it right after breakfast, here in California. My thoughts are to:

1) Eyeball everything when cold, to see if I can see anything obvious.
2) Start it and look at the engine tank to see if I see oil going into it.
3) Stop engine and ensure I can loosen the engine tank cap, then snug it back up.
4) Start engine, loosen cap, and watch for oil to fill tank. If it does, tighten cap.
5) Turn off engine and observe oil level to see if it drops.

If tank does not fill in step 4, at that point I should remove check valve to see it I can blow through it one way, correct?

**Basnova** · 07-27-2025, 10:06 AM

Originally Posted by David - WI

If it was the check valve, I would think the tank would leak down further when it sat longer?
With the crack in the tank it only leaked down to the crack, regardless of long it sat.

OK, I will look at level before I do anything, to see if I can determine if it's lower than when I last looked at it.

Do you think it's possible that it's always had a little air in the system since the very beginning, hence why it's randomly thrown beeps since 1998? And, maybe I only need to be bleed, or is that wishful thinking?

I would've thought that one of the service shops would have said something when performing routine maintenance and such, but maybe not.

**NICE PAIR** · 07-27-2025, 10:28 AM

Originally Posted by Basnova

This is all excellent information for me. Thank you. Just so I know, looks like there is no screen or filter on the remote tank pickup hose, correct?

#34 is the remote tank screen, If I remember correctly there is a check valve on the side of the motor that pressurizes the in boat oil tank (air pressure forces oil into the motor oil tank)

It's been a while for me on the 3 litres but your rich condition after sitting could be a leaking check valve in the vapor canister! (I'm assuming the oil pump pressurizes the oil into the canister, and maybe at shut down, the pressurized oil in the boat tank is finding its way into the canister, lowering the oil level and causing the rich mix) My $.02

**skialot2** · 07-27-2025, 10:33 AM

There is a screen at the bottom of the pickup tube in the remote tank. #34. Part# 32-99802

**David - WI** · 07-27-2025, 10:41 AM

Originally Posted by Basnova

OK, I will look at level before I do anything, to see if I can determine if it's lower than when I last looked at it.

Do you think it's possible that it's always had a little air in the system since the very beginning, hence why it's randomly thrown beeps since 1998? And, maybe I only need to be bleed, or is that wishful thinking?

I would've thought that one of the service shops would have said something when performing routine maintenance and such, but maybe not.

I don't think so, and yes any halfway competent mechanic would see the level down and look into it... but they probably just bled the air out and super-tightened the cap for you.

**XstreamVking** · 07-27-2025, 11:04 AM

I have two 3 liter EFI's and four 3 litre opti's that I own. The check valves have always been #1 problem child for me. 2nd thing would be the float in the tank on the engine failing. # 3 is the 90 deg check valve fitting where the oil hose connects to the tank on the port side of the engine leaking. (easy to see leak) Have only had 1 in boat tank crack in 20 yrs. jm 2cts...

**KIRCHNER** · 07-27-2025, 11:26 AM

i had the beeping thing going on, i was cleaning the remote tank[soap/water] where the lanyard attaches, invisible cracks showed bubbles, new cap problem solved..

**Basnova** · 07-27-2025, 02:01 PM

Originally Posted by skialot2

Amazon.com: Jetunit 27-42999T Oil Tank O-RING for Mercury Mariner Outboard Oil Reservoir Level Cap Gasket 25-11332 Sportjet 105/135/140/150/175/200/225/250/275HP DFI EFI JET : Automotive

Ok, checked it all out.

The only possible place it could have been leaking was at the barb connection at the bottom of the engine tank, where the clear hose is zip-tied. Not enough to even drip, but i could feel wet residue. I was able to move the hose up and down ever so slightly on the barb, but not enough to easily have the zip-tie slip down over the barb. Nevertheless, I replaced the zip-tie with the the type that has the curve on the connector, designed for hoses. The hose no longer moves up and down that teensy bit.

I measured how low the oil really was and it was 3" from the top of the engine tank. I, then, removed the cap on the engine tank. I remember the original dealer being pretty adamant that I don't ever remove that cap because the gasket could tear easily, so instead of just loosening it enough to bleed it, I decided to take it all the way off to inspect the gasket. Lo and behold, the gasket was torn right where the gasket goes under the lip on the cap. I removed the gasket from the cap and placed it on the tank to see where exactly that tear would be, and it was right on the outer edge of the neck. I took the gasket off the tank, and placed it back in the cap.

Leaving the cap off the engine tank, I started the motor and looked inside the tank. I could see oil being pushed up into the tank. I assume this means there is no air getting into via any other place in the system, otherwise it wouldn't be filling. I watched until it started filling up the neck. Don't know if this is correct or not, but while it was rising in the neck, but before it overflowed, I replaced the cap. With the cap on, I could not see any air in the neck. Please tell me if I did this wrong and should let it overflow, or if I should drain some.

Turned off the motor at the switch, then started it again. Let it run for several minutes, no beeping. Apparently, the sensor works. Rev'd it slightly, let it sit a few more minutes and shut it off. Tilted the motor up enough to get the oil level "leaning" on the cap, waited 10 minutes, checked tank and cap. Still full and no leakage. While I give it more time to see if it leaks at the cap or drops level, I came inside to post this.

Here's what I think:

I kind of wonder if the original dealer tore the gasket but didn't replace it because of where the tear was, and it wasn't leaking. That might explain why they were so sure to tell me specifically not to remove that cap. I know it's been 27 years, but I distinctly remember them telling me that the gasket tears easily, and "you don't want to do that!" They scared me, which is why I never removed it over all these years. Of course, this is just conjecture, but I think it's possible that the tear allows a tiny bit of air to bypass the seal. Over time, based on how long it sits, how much jostling while tilted depending upon far I tow the next time, pressure based on temps, etc., the air would take up space while the oil dropped and I would get the beeping until it ran long enough to fill the tank up enough to stop beeping. Because, after all, this has been going on over 27 years!

Now, me not touching that cap for 27 years, not even to snug it, perhaps after being compressed over all these years the gasket began to allow more air in through that tear, to the point where even though oil is being pushed into the tank, it's now competing with the air that's being sucked in. Just a theory, so, anyone, feel free to comment, even if to tell me I'm wrong. I don't mind. At this point, I'm just happy things seem to be working the way they are supposed be.

Based on my theory, I think I should replace that gasket. After all, even if it's not leaking oil, as I said, I think that a gasket that contiguously goes under a lip in the cap is designed that way for a reason. All this said, would you use this Jetunit gasket previously linked to above, or should I hunt down an OEM Mercury branded one?

Thanks again!

**Basnova** · 07-27-2025, 02:10 PM

Originally Posted by KIRCHNER

i had the beeping thing going on, i was cleaning the remote tank[soap/water] where the lanyard attaches, invisible cracks showed bubbles, new cap problem solved..

Was your engine tank still filling with the cracked cap? I would think not, correct?

**David - WI** · 07-27-2025, 02:37 PM

If the motor tank cap/gasket leak, the tank will overfill and leak when the engine is running... just like if the cap is off. He was talking (I think) about the cap on the "remote" tank in the boat.

**Basnova** · 07-27-2025, 04:08 PM

Originally Posted by David - WI

If the motor tank cap/gasket leak, the tank will overfill and leak when the engine is running... just like if the cap is off. He was talking (I think) about the cap on the "remote" tank in the boat.

I'm talking about a leak so small that oil won't pass but air will given enough time. That's why I should replace the compromised gasket. Or, are you suggesting that if oil isn't leaking out, leave the torn gasket as is?