350 Mpi Losing Oil

[SEA SALT]

Have a 2005 Sea Ray 320 SD with twin Mercruiser MPI engines and V-drives..currently with 142 hours on the engines. Recently took a trip from Brownsville, TX to Veracruz, Mexico...about a 700 mile trip which took us 38 hours, only stopping to re-fuel and we ran the engines at between 3600 and 4200 RPMs, most of the time at 3800. We started out with a fresh oil change but at the end of the trip the smartcraft guardian system came on, indicating low oil pressure. First on the starboard engine and later on the port engine, to the point where it would not let us rev the engines past 1500 RPMs. Checked on the oil and the dipsticks showed completely dry. There were no oil spills in the engine compartment and after a mechanic checked the engines there appeared to be no engine damage. Replaced filters, filled up the oil reservoir and the engines run fine but I am told there should not have been any oil loss and I am baffled as to where the oil went...any ideas out there?

 

[QC]

Re: 350 Mpi Losing Oil

We started out with a fresh oil change

Are you absolutely, 100% positive that they were full?

I am told there should not have been any oil loss

Well that's incorrect. All engines burn some oil. Some new ones burn more than some older ones and visa versa, and it is not fixed by, serial number (individual engine), model, year, age, hours, load etc. etc. this is in fact an imperfect science . . .

I am baffled as to where the oil went...any ideas out there?

Well I think you burnt it, either past the rings or the valve guides . . . the fact that both ran dry at a similar time, (equal to a whole season on many boats) tells me that they were probably not full. Also, I use oil in my 6.2 MPI, and I run similar loads and RPM at cruise I bet I add a quart or two a season, but that's 100 hours. Maybe somebody here has a "acceptable" oil consumption chart from Merc. . . .

How long have you had the boat? Has she used any oil before?

 

[JustJason]

Re: 350 Mpi Losing Oil

what brand and weight oil are you filling these engines with?

 

[SEA SALT]

Re: 350 Mpi Losing Oil

Thanks QC. I bought the boat and that was my first trip. I am reasonably sure the oil was full when we started as I had a surveyor do a boat survey before I purchased it. I am not sure if it was old oil though. The previous owner was an older gentleman who did not use the boat much and I have not gotten the maintenance records on the engines.

 

[SEA SALT]

Re: 350 Mpi Losing Oil

Hi JustJason.
The new oil added was Mercruiser 25W40 but since it was my fisrt trip I am not sure what the previous owner put in it but i would assume it was the same. i will ask though.
Thanks

 

[Bondo]

Re: 350 Mpi Losing Oil

I am reasonably sure the oil was full when we started

Ayuh,....

I'd say a Lack of Preventive Maintance on Your part is pretty much to Blame.....

Anybody who's about to Go Boating, should have enough Sense to Check the Fluid Levels, Before Each trip....
That means Every Day....
Especially before embarking on a 700 Mile trip...

Did you do this 38hr. trip in only 1 non-stop Run,..??
Did it ever dawn on you the Check the Oil, when Refueling,..??

'ell,... I've Fired many a Truckdriver for Not checking the fluid levels,.. Every Morning....

I suggest you file a "Cruise Plan", with Somebody, every time you go out....
With your lack of Thinking,+ Planning,...
It would be nice to narrow down the Search area for the Coasties when the day comes that you Don't Make It.....

 

[SEA SALT]

Re: 350 Mpi Losing Oil

Hi Bond-o...you are 100% spot on. Hard lesson for me and fortunatelly nothing really bad (at least not right now anyway) happened from it. I have learned and now check things every time before I leave. However, even though your criticism is correct, I still have no real good explanation as to where the oil went other than maybe it just burnt away.

 

[SEA SALT]

Re: 350 Mpi Losing Oil

Thanks Bubba.
I agree but just don't know if they should have used that much oil under these loads. Guess my concern is that there might be something wrong and I am looking for advice on what to watch for.

 

[Bondo]

Re: 350 Mpi Losing Oil

However, even though your criticism is correct, I still have no real good explanation as to where the oil went other than maybe it just burnt away.

Ayuh,...

A Full Service,+ Tune-up, starting with Compression,+ Leak-down Tests will probably give More insight into that question,...
Than is possible from Us, sitting 1000s of miles away....

 

[HT32BSX115]

Re: 350 Mpi Losing Oil

Howdy,


I hate to jump on the this bash wagon but a 38 hr run at near WOT should have resulted in a more than 40 gallon per hour burn rate.

With a 200 gallon fuel tank I would assume you would have filled it up about every 4 hrs or so of run time?...........maybe 8-10 times?

For most of us that would be 8-10 oil and other engine component checks along with maybe other checks like maybe the generator etc. (My boat has a 44 gallon tank. I check the oil every time I fill it or every time I put it in the water....The engine has about 140hrs on it since new))


There have been many threads on various boating sites asking if it's "OK" to run at WOT or near WOT for short periods of time or longer.

Any time you run an engine at (or near) WOT you put a pretty high load on everything and possibly increase oil consumption.

I would never run an engine at that high a power setting continuously. And if I did I would be checking the gages and oil level etc pretty closely........especially if the boat was new (to me) because you never know how much oil any engine will use until you've run it a while. Every one of them are different.

If you did not run your engines with zero oil pressure (at all) you have really lucked out and probably caused no damage.

Any number of things could cause excessive oil consumption, but you now need to check these engines very closely to determine if they really have excessive consumption by starting with a known oil level in each engine.........then check and record hours/oil levels to determine the actual oil consumption (or leak rate)

Once you have some real numbers you can start looking for the reasons.

It's (possible, but) unlikely that both engines use exactly the same amount of oil per hour....


Good luck,


Rick

 

[QC]

Re: 350 Mpi Losing Oil

These might be rated as high as 5200 RPM WOT, so a cruise at 3800 is not that severe . . .

 

[JustJason]

Re: 350 Mpi Losing Oil

Damm Bill you were harsh!!!!

SeaSalt. A boat your size + with the time and length of the trips you take you should really try to keep a log on everything. Fuel consumption, oil consumption, hours, etc.
Being a new boat to you as well, you should probably have a compression test done on both motors and keep a log of that. Then every 2 to 3 years have one done again, and compare them to the ##'s in the log.
You should also come up with a checklist, just like airplane pilots do, for every time you go out. Especially on those long trips.
Remember.... when you break down in a car it's a PITA.... but you can always walk home. When you break down in a boat..... you aren't always going to get home.

Had 2 fisherman die last week of the coast of Gloucester. Boat fire. Wonder if working extinguishers was on their checklist.... or if they even had one.

 

[HT32BSX115]

Re: 350 Mpi Losing Oil

These might be rated as high as 5200 RPM WOT, so a cruise at 3800 is not that severe . . .

He did say 3800-4200.......I guess I was thinking more of my 454 that is rated at 4200-4600.

I suppose a lot of those SBC engines do have WOT ranges up to 5200..... 4200 would probably be around 80% power then?

 

[Bondo]

Re: 350 Mpi Losing Oil

Ayuh,....

Regardless What the WOT rpms are,...

Most Any boat I've ever been in, had it's Sweet Spot somewhere between 3000,+ 3500rpms.....

 

[HT32BSX115]

Re: 350 Mpi Losing Oil

My 21' 454 powered boat runs REALLY nice at 3000 rpm (30 mph, 10 g/hr)

 

[QC]

Re: 350 Mpi Losing Oil

Most Any boat I've ever been in, had it's Sweet Spot somewhere between 3000,+ 3500rpms.....

I agree, and I think I burn more oil when I spend a long time at 4000+, but mine's a wannabe go fast, so I'm supposed to act like an idiot . . . I would just not call that cruise RPM necessairly abusive, and yup, around 80% . . . depending on the existing rating which I don't think we know . . .

FWIW, Merc says you can leave at 100% all day long . . . but, they also mention oil consumpiton and longevity issues . . .

When I get all worried about this stuff I always think about prime power gensets, and then I feel better . . .

 

[Silvertip]

Re: 350 Mpi Losing Oil

You've had this explained to you several times in this thread. THE ENGINE BURNED THE OIL. The only way out of the motor is to leak out in which case the bilge would be full of oil (and I will assume you actually looked in there). And just because you had a surveyor go over the boat does not mean the engines were full at the time of departure. The other way for oil to get out of the engine is to have it pass through the combustion chamber and out the exhaust -- as in IT BURNED IT and the latter is likely the case. A marine engine at those heavy load levels creates very low manifold vacuum levels and oil consumption can and will increase under those conditions. Look at it this way -- the 24 hours of Daytona has sports cars running at high rpm for 24 hours and the engines are basically toast at the end of that period. NASCAR cars run WOT for 500 miles at between 7000 and 9500 RPM and are toast after 4 hours. You ran at nearly WOT for 38 hours and are wondering where the oil went. And you should be flogged for not checking the engine bays, including the oil level at every fill. And a check of the gauges every few minutes would have also shown fluctuation which would have been a clue that there was an issue. Ever wonder where the term "idiot lights" came from and why they installed them in cars? But then you likely didn't have oil along anyway so it is all a moot point. Taxpayers continue to have to rescue the careless (or should I say thoughtless) which could have been your situation. Sorry to be critical but you dodged a huge bullet and risked the safety of anyone you had with you on that trip.

 

[DJ]

Re: 350 Mpi Losing Oil

Settle down everyone. The guy admits he learned his lesson and will spend more time in his engine room.

I think he understands that the oil was CONSUMED.

Let's all hope his engines survived this lapse prudent care.

I'm glad he didn't blow up the engines in Mexico. What a catastrophe that would have been.

 

[Bondo]

Re: 350 Mpi Losing Oil

Damm Bill you were harsh!!!!

Ayuh,..... Sorry Capt'n,....
I prefer to think of it as Brutally Honest.....

Sea Salt,.....

I apologize for coming off so Harshly,....

You've been up front,+ extremely Honest,...
I'm Glad you found Us, so We can help you learn what it takes to make Boating a truely Enjoyable experince,...
Rather than a Life Threatening 1.....

Welcome Aboard to the forums here at iboats.com....
I can only speak for Myself,.. But,...
I think you've been Flogged enough,..... Good Luck,+ Let Us know how the diagnosis works out......

 

[chiefalen]

Re: 350 Mpi Losing Oil

Welcome aboard !

My 2 cents glad your home safe and sound.

A lot of great info just given you, use it wisely.

I hope you keep coming back, learning more, and one day give back to someone else in need of info you gleamed here.

Keep a log of the compression check, you have performed at your earliest appointment you can make.

Check the oil every time you board the boat to leave the dock. And before you leave the boat after returning to the dock.

Also when in the engine bay touch the alternator belts see if tight and double check the bilge for any fluids.

Keep a box on board with spare belts, tools and such, so next time out and a belt goes you have it and the tools and knowledge to change it out.

After all you want to have fun on the water, not a nightmare like breaking down and facing a life threating situation.

Good luck !