4-Beep Oil(?) Alarm

**David - WI** · 07-27-2025, 04:41 PM

You initially said, "Looked at the engine-mounted reservoir, and it was 2" or so from full, as it's always been."

If the cap/gasket was leaking air, the engine-mounted reservoir would fill to the top (or overfill) every time you ran the motor.

**Basnova** · 07-27-2025, 08:37 PM

OK, well I ordered an OEM gasket anyway, and will put it in when it arrives. In the meantime, I am not scheduled to fish for at least another week, so in the meantime, I will keep the motor tilted just above the trim rams to see what happens, if anything, to the oil level, as well as monitor that cap for any leakage.

On another note, I have always stored the motor in this position because I didn't want to keep pressure on the rams. Is it ok to store the motor in the vertical position, which puts pressure on the rams?

**David - WI** · 07-27-2025, 08:48 PM

I don't think it matters. Running, you have probably 1,000# - 2,000# of thrust (depending on the prop) at the prop... with maybe 2:1 leverage on the rams.

I trailer and store mine trimmed all the way down.

**Basnova** · 07-27-2025, 09:06 PM

Originally Posted by David - WI

You initially said, "Looked at the engine-mounted reservoir, and it was 2" or so from full, as it's always been."

If the cap/gasket was leaking air, the engine-mounted reservoir would fill to the top (or overfill) every time you ran the motor.

I just re-read your post, and thinking I must've mis-interpreted it the first time I read it.

That said, well, if it's not leaking air, and you say it would've filled up the tank even if it was, why was it always 2-3" low? I mean, it filled up pretty quickly when I removed the cap. I do realize that this motor chows the gas and oil like there's no tomorrow, but there's no way it drinks the oil faster than it was filling, so I take it the fill speed is good. So, that, in combination with what you're saying, would indicate that it must always have been low, right? It's not leaking oil in any appreciable amount that would allow the oil tank level to drop into beeping range. One thing I did notice was that the fill tube was not nestled in the clips on the side of the tank. Does that mean anything? I know for a fact that it used to be in the clips, so I put it back upon first inspecting this morning.

Unless something is allowing it to drain back down the fill tube? Skialot2 mentioned a check valve on the starboard side, but I thought if it was bad it wouldn't allow the oil to fill at all. He did mention removing it and try blowing through it, and that it should only allow passage one way. Hmmm, I didn't make note of how low in the tank that filler is, but if it's at 3" below top, maybe that is the culprit. But, If it does allow passage both ways, would it still be able to fill the tank when the engine is running?

On that same vein, what happens if I try to unscrew that fitting (check valve?) at the block that the tank fill hose is connected to. Will oil come rushing out? And, does it have some sealant in those threads?

Thanks again.

**David - WI** · 07-27-2025, 09:34 PM

I'm just guessing that a bad check valve would allow the engine-mounted tank to drain completely... say over the winter; but maybe the oil draining back adds pressure to the boat mounted tank and it stops???

I dunno.

**Basnova** · 07-27-2025, 10:40 PM

Originally Posted by XstreamVking

Most merc dealers will have them. Boats . net is also a good place to look parts up online. Just look by serial number and part type. I think you may need part # 7 off this diagram. https://www.boats.net/catalog/mercur...ck-and-end-cap CHECK VALVE
Part #432783 is what I come up with. 33 bucks or so But do a search with your serial number and double check. Pull yours and try and blow back thru it. It should only go one way.

My serial number goes right to what you linked to above, so thank you for that link. As you can tell, I've not pulled one before, but in case I end up having to test the check valve, I have some questions:

When I disconnect the hose from that connector, I'm thinking of sticking some kind of bolt or something into the hose to prevent oil spillage, but won't oil also come pouring out of the block through the valve? If so, any recommendations on what to do about it? And, what about when I remove the check valve? Will oil continue to come pouring out of the block, too?

As far as inserting it, or a new check valve, back in, do I need to use a thread sealant or something, is there an o-ring in the seat, or does it simply seal when the check valve seats in the block? Also, any idea how tight it should be?

Thanks again.

**Basnova** · 07-28-2025, 08:38 AM

Originally Posted by David - WI

I'm just guessing that a bad check valve would allow the engine-mounted tank to drain completely... say over the winter; but maybe the oil draining back adds pressure to the boat mounted tank and it stops???

I dunno.

The fill point on the engine tank is up high. So, once the oil drops below that point, wouldn't it not be able to continue draining? I wonder if the tank is specifically designed with a high fill point as a safeguard against the exact scenario we are talking about here.

**Basnova** · 07-28-2025, 08:41 AM

Originally Posted by XstreamVking

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...

When the check valves failed, did the engine tank drain all the way down, or to just below the point where oil enters up high on the tank?

**XstreamVking** · 07-28-2025, 01:54 PM

If your engine oil tank filled quickly at idle, the check valve is probably good. The oil should not drain out of the engine tank under normal use. Now that it's full run it and check it next day just to see if the level stays full. If it does, you are good to go.

**Basnova** · 07-28-2025, 10:50 PM

Originally Posted by XstreamVking

If your engine oil tank filled quickly at idle, the check valve is probably good. The oil should not drain out of the engine tank under normal use. Now that it's full run it and check it next day just to see if the level stays full. If it does, you are good to go.

I just checked it, and the level has dropped overnight to right below the point where the oil normally enters the tank. To be clear, I have the motor tilted 30 degrees or so, and the oil level now is right below where it would normally enter via the hose opening near the top of the tank. I'm going to check in the morning, but if the level stays where it is, it must be running back down into the remote tank.

Originally Posted by XstreamVking

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...

I can't tell, but is one of the functions of #3 you mentioned above back-flow prevention? That's the only thing that looks like it would prevent the oil in tank from running back out through that hose filler opening 3" from the top of the tank.

**skialot2** · 07-29-2025, 02:21 AM

I think you need the vent fitting #15. It's really a vent but I think there is a check valve to stop the bleed back to the main tank.

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Amazon.com: PARTSDEPOT Brass Fitting Compatible with SIERRA 22-424254 : Automotive

**XstreamVking** · 07-29-2025, 05:32 AM

Yes, I agree. Looks like the 90 deg fitting is bad. Never had one do that. Usually they leak out of the 3rd nipple when they fail.

**Basnova** · 07-29-2025, 11:51 AM

OK, so it sounds like we don't know exactly how this part works, and it's a reach to think it has two check valves in it - one to let air in when it needs to, and one to prevent oil backflow, so I'm going to assume it doesn't have a backflow preventer in it, and because it's not leaking, it might just be fine.

According to some other replies on this thread, this system is supposed to be airtight, right? So maybe I'm looking for an air leak that's causing a siphon effect to pull the oil back down the engine tank fill tube. Along that vein, I just removed the caps on the remote tank. I don't know how to describe this, but diameter shape of them is fine as they sit in the caps just fine, but their "thickness" shape is far from round. They've taken on the shape of how they've been compressed. They are also not soft and pliable, but rather firm, although not hard, but to remove them from their seats would require sticking a screwdriver under them and prying, so I didn't go that far for fear of ruining them. Are they supposed to be like this?

Here's something interesting. When I removed the cap with the hoses, there was a piece of thick, coarse and stiff thread laying across one part of the lip of the tank. It looks like one of the strands that make up a nylon rope, kind of like what a strand form the twine lanyard on the fill cap might be like. And, it looks like it's been there forever, because it was stuck to the tank lip, and the thread's shape is compressed across the width of the o-ring. The o-ring rubber is definitely not pliable enough to push back out that indentstion, and when I run my fingernail across the indentation of the thread, I can easily feel the edges of that indentation. I can see how that thread laying across the o-ring and lip of the tank prevented that o-ring from having complete, unabated contact with the tank lip, but not sure if that would have caused an air leak, or if the thread would have prevented an air leak by virtue of being compressed in there, if that makes sense.

I wiped off everyhting really well, put the caps back on, manually filled the engine tank, and tilted the motor back up, just for grins. If it is airtight, even if there is now air in the remote tank oil line from me pulling out the pick up tube, would an airtight system prevent oil from going back down the engine tank fill tube? And, would an air leak cause the oil to retreat from the engine tank?

Regardless of what happens, given the shape and condition of the original 27 year old o-rings, I'm thinking I should replace the cap o-rings. Is that a sound thought?

**Basnova** · 07-29-2025, 12:23 PM

What is the best way to check for an air leak? I assume the motor needs to be running, or can you do it when off? There's only a handful of places between remote tank and engine tank, right? Or...?

**XstreamVking** · 07-29-2025, 12:49 PM

Try and blow back into that fitting thru the hose that feeds to the engine tank. (open the boat tank first) That little 90 deg ell has a check ball in it that's set to approx 3 psi. If the system ever gets over pressure it's the "blow off" relief part. That's why I said they usually leak oil from the 3rd nipple if they fail. Good find on the piece of rope in the cap, don't think that's the reason the levels falling in the engine tank though. There's only 2 hoses on the tank on the engine. One feeds in at the top thru that little brass fitting, other feeds the oil pump from the bottom. Oils going out thru one or the other. Never seen an oil pump leak into the VST but could explain the massive smoke show you were indicating at start-up.