Mercury Black Max 150 issues

[newbie123]

I've just bought a boat with an older engine and have been having a few issues
can anyone help?

It's a Mercury Black Max 150 V6, not quite sure on age

1: Oil
While the engine is running, an intermittant beep is constantly sounding which began when the oil ran low, which i presumed was the low oil sensor.
refilled the oil and the beeping has not stopped. Is this likely to be the sensor itself?

After an hours run, all fine, we trimmed the engine up to go over a shallow patch and oil began dripping out of the engine cowelling, so we killed it and took the cover off. It seemed to be coming out from the cap in the tank inside the engine and from the seal around the pipe feeding in.
If the seals need replacing, could this be the problem with beeping? would lack of oil pressure in the tank inside the engine cause the beeping even though the exterior oil tank was pressurised?

2: Batteries
Having had the first run,we turned off the isolator on both batteries (one dual switch) and left the boat on the trailer
when we came to use it a week later, both batteries were dead.
It has a small 100AH battery (presumed starting battery)
and a larger 80AH battery (presumed leisure battery)
we took the smaller one home and charged it overnight and it had enough juice to start the engine.
we ran it for an hour with the isolator turned to the larger battery to try and charge it.
We then left it on a pontoon for 2 hours, arrived back and put the isolator onto both batteries to start and nothing, then tried on the smaller battery and nothing again.
So ended up jump starting it.
The batteries are fairly new.
Would running it for an hour give it enough charge to start the engine or have i got an alternator problem?

Thanks

[spartacus]

Welcome to the forum.

Regards batteries - are they wet cell or maintenance free? I would leave on a trickle charge with battery charger for a couple of days, rather than running the engine. You will need to test the strength to determine if they are servicible. On a full 100% charge (leave for 12 hours before testing) - a 12v lead/acid battery you should achieve output 12.6-13.9v. I would test this first to eliminate this as source of problem. Definately seems to be a drain somewhere? Useful link here: http://www.batterystuff.com/tutorial_battery.html#6

[newbie123]

thanks

I have a funny feeling the isolator may be faulty. there is nothing running outside the isolator because the boat is kept on a trailer so the bilge doesnt need to be outside. they are maintenance free batteries.

We've got them trickle charging now so hopefully will be ok, but I thought it was a bit odd that they would run flat with nothing outside the circuit.

But I will post findings when we have tested it again.

I will also test the output when ther are charged

Thanks

[BumbleAbout]

Disconnect the postive lead from one battery and put an ammeter between the battery positive terminal and the floating lead - if there is current flow with the isolator off then:
- there might be a short between the battery and isolator switch (I don't know how long a cable run it is)
- the isolator switch might not be isolating everything (is anything wired in before that in the circuit - perhaps on the wrong (i.e. battery) side of the switch contacts by mistake ?

[newbie123]

It's only about 50cm of cable between the batteries and the switch and i cant see a short. there also isnt anything between the isolator and the switch, everything runs off after the isolator.

I will try testing the connections later

thanks

[jwalker]

Your oil problem... the beeping indicates no lubricant it reaching the engine. Fill the remote oil tank, fill the engine reservoir tank. Check the condition of the seals in the cap and check for splits in the tank and hoses. The oil level sensor is part of the cap and is magnetic so can be checked by removing the cap and moving the float.

Disconnect the rod which connects the throttle levers to the oil injection pump lever and move the lever on the pump to the maximum open position. Adjacent to the connection for the oil outlet on the oil injection pump you will find a bleed screw, slacken this screw a number of turns and allow the oil to purge the tubes and oil pump by flowing from the engine reservoir. The reservoir cap may need to be slackened. Any air in the outlet tube from the oil pump should purge itself when the engine is running.

There is a rotation sensor inside the oil pump which is triggered by a small magnet which is in the oil pump drive. If the pump drive fails, which they do, the sensor will not be energised by the magnet and the warning buzzer will beep. When the warning sounder is beeping, do not run the engine unless you are using 50:1 oil/fuel mix.

There is also a 2psi pressure release valve on the feed tube from the main oil tank, it has an open ended tube attached to it. It shouldn't be leaking oil out or air in. Its purpose is to leak air in if there is a fault in the oil system to prevent petrol being drawn into the main oil tank via the oil pump.

Be sure to tighten everything and reconnect the throttle to oil pump levers when finished.

Oil flow can be checked and also oil flow quantity can be checked via the oil bleed screw while the engine is running but 50:1 mix should be used while doing this. Data is available re the quantity of oil which should be expelled during this test.

[jwalker]

If there is nothing connected to the batteries and the switch is sound one or both batteries must have a fault if they discharge quickly.

[jwalker]

There is also a 2psi pressure release valve on the feed tube from the main oil tank, it has an open ended tube attached to it. It shouldn't be leaking oil out or air in. Its purpose is to leak air in if there is a fault in the oil system to prevent petrol being drawn into the main oil tank via the oil pump.

Sorry, that italic bit is wrong, I misremembered it. There are two 2psi. valves, the one mentioned above and another one at the junction of the oil and petrol pipes. It's the later that is used to prevent petrol entering the oil system. Also, the oil pump rotation sensor is right adjacent to the oil pump but not part of it, it has three leads. I hope that's clarified the setup for you.

[Bigmuz7]

Originally Posted by jwalker

If there is nothing connected to the batteries and the switch is sound one or both batteries must have a fault if they discharge quickly.

Before the JW dude posted that .. I was gonna say the same .. if you can get access to a heavy discharge tester, you can easily find this out by charging your batteries fully and connecteing them to this type of tester, it will show up any 'dud' cells by dropping battery output very quickly as it mimics a heavy load. Good batteries should be able to hold up for a specified term, but you would see a dud one drop off very quickly .. this is similar to the type I use and its very reliable