Engine alarm on Mercury Bluewater 350, seeking help, advice

[Raymond14]

Hello, I am posting for the first time and I looked but did not find my subject. If I missed it sorry. Here are the facts. 1997 Bayliner 3388, twin 350 s . End of last season ( start of last season replaced both impellers as well as gen set) started getting an alarm sound (like when you first start engines ) it would come and go. We had just lost our life long friend and marine mechanic do an unexpected death ) . First ran a manual check of oil pressure, engines fine. Then checked oil pressure sending unit. Disconnected and alarm stopped. Winterized boat and decided to have at it this year. This year, my son's friend a certified GM (auto) mechanic and electronics whiz) ran another oil pressure check, OK. Tested the oil pressure switch, said it was working. Played with connections, alarm disappeared. Came back a couple of weeks later. It is intermittent . When it comes on, the oil gauge (on bridge ) drops, sometimes(it seems) if you tap gauge, alarm quits. At any rate when ever it quits, oil pressure gauge goes back to normal range. Other than this, engines run fines. Son drives the boat, Last time he was out he said it sounded like "maybe" more than one alarm, was not sure, but again intermittent . Without our dear friend, seeking guidance on where to look and what to check. Any help would be great. The engines have been well maintained and have about 400 hours on them.

 

[Bt Doctur]

the oil pressure sending unit has nothing to do with the no oil pressure alarm switch. It should alarm for high engine temp, high transmission temp or no oil pressure

 

[alldodge]

Howdy

Just to make sure were talking the same motor, post the serial number of one of the motors, and are they EFI or MPI?

Being a 3388 I'm assuming they are inboards and use velvet drives. The top 2 things that can give a solid alarm are, over heat and low oil pressure. The gauge does not set off the alarm. The alarm will sound off IF the oil pressure switch is bad and closes to soon, or when pressure is low. Looking at the gauge drop is not good but does tell you there is a problem with the oil pressure. The switch is set around 5 psi, and you should have more then that.

When the oil pressure was checked, was it done with a mechanical gauge?
Have you checked the oil level?
What weight of oil are you using?
When the alarm sounds, how low is the oil pressure?

 

[Raymond14]

Finally figured out how to respond. First, my son's friend said he tested the sending unit. Serial number on engine OK189O44/ OK189O45 . Carbs. When the oil pressure was checked it was with a manual gauge. I was told it was very good. They advised they checked the oil level and I am not sure what the oil weight is, it was put in by the marina. The port engine, 2000rpms showed about 25 on the cabin gauge and nearly 30 on the bridge. This was observed after warming the engines. During this time the alarm sounded twice. Both times the gauge read about 10. This occurred at idle or low, rev up the engine the alarm stopped. I hope this helps.

 

[alldodge]

It does sound like you have a real low oil pressure issue. If the marina is using 10W30 then the oil is not heavy enough, should be at least 10W40, 15W40, 25W40 or if in warm climates straight 40W.

The reason I wanted to check the oil is to see if it is over filled, or to low. Being an inboard you have a block mounted fuel pump. If the diaphragm has a leak, it will start putting gas into the motor. the gas will dilute the oil and cause low oil pressure. Left long enough and you will have bearing failure

Your motor break down
http://www.mercruiserparts.com/5-7l-mie-gm-350-v-8-1997-0k040307-thru

 

[Raymond14]

Will check oil and ask what they use. Thank you.

 

[Raymond14]

Talked to marina, they use straight weigh 30 Wolfshead. Check port engine, full to top mark. Ran at idle 10 min . no alarm , stayed around 15 lbs at idle 800 rpm and 2000rpm went to around 25lbs. Starboard engine oil mark half way between full and low. Idle same amount of time at idle 800 lbs. ran bit closer to 20lbs, at 2000 rpm, went to about 30lbs. Could not get alarm to go off. One guy said the engines seemed to idle too low.

 

[alldodge]

Does show Wolf's Head (AOC Oil Inc, Tamps FL) has API certification, but the 30W is to thin and only recommended for temps of 32 to 50 degrees F. Not bad mouthing the oil, but the only reason there using it is because its cheap cost. Charge 100 for an oil change, and pay 2.50 a QT for oil, not bad profit. In any case you need 40W.

The rule of thumb for pressure is 10 pounds for ever 1000 rpm's. The worst part about using lower then specified viscosity oil is you can have more wear. Once the wear has happened you cannot get it back

Also if your marina is using low quality oil filters, I would go out and supply my own to them, stay clear of Fram and others like them

 

[Raymond14]

Sorry this took so long, being summer and all, took a while to get it going. My son is a directional driller and is very busy, I have bad knees , couldn't get in there. At any rate The oil was in need of a change and low. Did as you suggested , Quicksilver 25W40. Runs great and no alarms. Thank you so much. Greatly appreciated.

 

[alldodge]

Many thanks for coming back with the closure statement. Happy boating

 

[Raymond14]

All alarms have quit. My son took the boat out today and checked the oil levels. Shows too much oil on the dip sticks. This is crazy. When putting new oil in, it was carefully measured . 5 quarts and n a half with filter . Which is what the owners manual calls for. Still no alarms but no idea why it would show too much oil. Once again, any ideas or direction would be greatly appreciated.

 

[alldodge]

Being a 1997 you should have an engine mounted fuel pump, and if so your pump is leaking fuel into the oil. So your mixing gas with the oil

 

[Raymond14]

Thanks , will look into it

 

[Raymond14]

Sorry s long in responding back. Turned out to be an oil issue, a bit too much. Removed, everything ran well. Then ,,,,, next outing, starboard engine oil pressure gauge stared bouncing like crazy. then according to my son, it quit, went to normal. Engine ran strong and no alarms. Dock neighbor said that it is most likely a loose wire or the like , because of all the screwing around.