Author Topic: Loss of Engine Oil (Read 7405 times)

1simon · « **on:** July 24 2018, 23:13 »

Hi All,

I have an Ocean CC 38 with a VP MD22l 50hp.
Recently, in a crossing, due to lack of wind, I ended up motoring all the way (13hrs each way).
I set out with the oil level at the Max mark on the dipstick and having checked when back I have noticed that the level is now down to the MIn mark.

There is no visible sign of any leak anywhere in the engine bay.

How worried should I be?

Thanks

Simon

Salty · « **Reply #1 on:** July 25 2018, 08:00 »

Concerned enough to check your oil level more frequently. Your post indicates that the engine ran for 26 hours in total between setting out and return to your home port, but you didn’t mention whether the oil level was checked prior to starting the return leg. So without that information it’s not clear whether something may have happened on the way out, or just on the return passage to result in the loss of oil. Assuming you have not experienced such oil losses in the past, it would indicate that tolerances in some part of the engine are now sufficient to allow oil to escape or be burned within the engine. Does your boat leave an oil sheen on the water as you progress under power, or is the exhaust a bit more smoky than before?
A point to also consider when running the engine and “motor sailing” is that there is a heel angle limit, beyond which use of the engine is not recommended and previous use of it under such situation may have initiated the wear leading to your present problem.

geoff · « **Reply #2 on:** July 25 2018, 08:32 »

My md 22l has always used a fair bit of oil right from new, so much so that after 2 years the engine was removed under warranty and checked . No faults were found and the engine continues to use oil , but starts and runs well. After 26hrs 1/2ltr of oil is not too bad. Geoff

1simon · « **Reply #3 on:** July 25 2018, 08:50 »

Thanks for your comments.

Yes, I did check the oil level prior to start of return journey and noticed loss of oil, so I can conclude that the oil loss was gradual throughout the entire journey.

I did notice loss of oil last year after a 10hr journey, so the problem has not started now.

No visible smoke except when I push the engine revs up to near 3000rpm ( max rpm)

I do not motor sail so I am not aware of extreme heeling while engine is running. But I cannot vouch for previous owner/s.

Am not aware of oil sheen behind the boat, but will check next time out to be sure.
It would appear that oil burning is the issue.

So what are the potential problems associated with such loss of oil, apart of course from checking and topping regularly?

Will of course discuss this with my mechanic , but thought i would post here to check feedback from forum.

Simon

Noelio Abrunhosa · « **Reply #4 on:** July 25 2018, 14:02 »

hi
when last did you change the engine oil. its common for very little used engines to burn oil during long runs. there is always some moisture content that gets evaporated once oil warms up. also if engine not used regularly there is always oi that bypasses piston rings and valve stem seals.
usually nothing to worry about. change oil and filter with good quality oil. cheaper oils tend to breakdown earlier.

good luck and happy sailing

regards

Abby

Yngmar · « **Reply #5 on:** July 25 2018, 14:23 »

Our MD22L is eating a bit of oil too when the oil is getting a bit older. We're mid season now, motored maybe 60 hours, the oil has turned black some time ago and needs topping up occasionally. When the oil was fresh, it didn't use any. Same last year.

The engine starts and runs very well and we have recently used it for around 5 hours at wide open throttle fighting upwind in a gale (doing a measly 3-3.5 knots SOG) and it handled that fine. It only smokes when increasing RPM after a while of low RPM motoring/motorsailing, and only for 30 seconds or so - I assume that's carbon deposits being burnt off. We do turn up the throttle full to clear that out every few hours.

I'm not worried about it in the least - good engine. Rated for running at 30° heel by the way. It'll get fresh oil in winter. If you're worried, you could do a mid-season oil change and it would probably stop oil consumption again.

1simon · « **Reply #6 on:** July 25 2018, 15:52 »

Thanks for the comments.

Last engine oil change was done in 30th May, and I have not used the engine that much - prior to the oil change the boat was hardly used since last October.
Since the oil change in end May, I would say the engine has been used for 6 hrs, prior to the long voyage mentioned, so it does not fit into the theory that it burns oil when the oil is old.

I normally motor at 2000 to 2500rpm.

JEN-et-ROSS · « **Reply #7 on:** July 26 2018, 08:51 »

Hi, 1simon.
Are you using a suitable grade? We have a BETA 30 so I can't comment on Volvo Penta,
but we also have a couple of motorbikes, one being a venerable 1980 GS1000G. Several years ago I accepted the advice of an 'expert' and changed from the old mineral oil to a 'modern' synthetic equivalent.
Normally the bike used very little oil but after changing to the new oil it required topping-up after every trip.
So I changed back to the old mineral oil and, hey presto! back to the way it was before, very little topping-up required.
Could the grade that's been used been accidentally changed?......just a thought.....

IslandAlchemy · « **Reply #8 on:** July 26 2018, 11:33 »

It's an old BL block from the 1970s. They have lways drunk a bit of oil, as did all car engine back then.

The most common reason for oil use is the bores getting polished due to the engine not being worked hard enough or oil getting past the valve guide seals.

Use a mineral 20/50 oil and give it an Italian tune-up every so often.

Don't use a synthetic or semi-synthetic oil (it will start to leak), and 10/30 is too thin and will find its way past the rings too easily.

1simon · « **Reply #9 on:** July 26 2018, 16:21 »

I am sure that the mechanic advised that he had used an oil with suitable viscosity as I had already advised him that I had noticed some loss of oil ( athough not on the scale I have describedon the 26hr trip).
But I will check the grade, to be sure.

What is an Italian tune up please?
And what do you mean by "bores getting polished due to the engine not being worked hard enough"?

IslandAlchemy · « **Reply #10 on:** July 27 2018, 09:43 »

An Italian tune-up is basically giving the engine an hour at high revs to get it really hot and burn all the sludge out.

Bore "polishing" happens when you have an engine running under no load for hours on end (for instand if you leave your engine running at anchor to charge the batteries). The cylinder bores have tiny helical scratches in them which the oil sticks in, to provide lubrication between the piston rings and bores. Polishing is when those sratches literally get "polished out". Without the scores in the cylinders, the oil just pushes past the rings and burns, as it has nothing to grip to in the bores. Hence you get high oil usage.

If the bores get polished, you can replace the scoring by removing the cylinder head and using a special tool.

1simon · « **Reply #11 on:** July 27 2018, 14:58 »

Thanks everyone for all your comments, which have been extremely helpful in understanding the problem better.

geoff · « **Reply #12 on:** July 27 2018, 15:58 »

Hi Simon as a matter of interest what speed do you get at 2500 rpm?. Geoff

1simon · « **Reply #13 on:** July 30 2018, 15:42 »

Geoff, in response to your question hull speed at 2500rpm will depend on sea conditions , but if sea is calm should be around 7.2knts

dawntreader · « **Reply #14 on:** August 01 2018, 08:35 »

That's interesting! At 2500 revs in calm seas I get about 5 - 5.5 knts in my B37 with a D1-30. That's a big difference to your boat's performance

geoff · « **Reply #15 on:** August 01 2018, 08:41 »

Simon , With the same engine and Kiwi prop I get 7kts at 2100rpm . I find if I use any more revs the stern just digs in and I get hardly any increase in speed [but lots more fuel!] Geoff

JEN-et-ROSS · « **Reply #16 on:** August 01 2018, 08:50 »

That is interesting dawntreader.
Our older and heavier B38 with 30hp BETA and VP 3 blade folding prop will, at 2500rpm, like 1simon, do about 7.0kts in calm sea.
Having said that the fuel consumption is rather high at 2500rpm, so we motor at 2000-2200rpm giving 5.9-6.1kts.
The variations are interesting, I wonder if anybody can explain why?

Salty · « **Reply #17 on:** August 01 2018, 10:18 »

Quote from: JEN-et-ROSS on August 01 2018, 08:50

.
.
.
The variations are interesting, I wonder if anybody can explain why?

1. Actual prop diameter x pitch,
2. Degree of fouling on the hull and keel,
3. Smoothness of the hull and keel,
4. Shape of the hull,
5. Trim,
6. Draft (this being due to weight, (are your tanks always full compared with others kept less full, number of persons normally onboard, ancillary equipment such as liferaft, dinghy, outboard motor, spare sails, spare ropes, number of fenders, etc., etc.,).
7. Waterline length,
8. Current. (One of the marinas where I kept a boat would open the gate from three hours before high water and shut it again three hours after high water and in consequence we were always batting the tide.
9. Are your speed indications “through the water,” and if so are you sure your speed log is reading correctly,
10. if your speed indication is “over the ground” have you allowed accurately for any current.

Well there’s a few things to consider !!

tckearney · « **Reply #18 on:** August 01 2018, 10:19 »

I have a B42 2000 model with the same engine MD22 50HP. I have a Brunton Auto prop filled. I can not get up to 2000 revs without the boat digginig in so much that the scoop is under water. At 2000 RPM I am doing 8 knots on GPs 9.2knts on the sea log. I have just completed almost 50 hours of motoring in the last ten days and have averaged 2 ltrs an hour 105 ltrs in 51 hours running to be exact. It is very surprising to me when I hear comments about 3000 RPM. I cant imagine what would happen If I pushed the Revs up to that. I would normally run at 1600RPM giving me 6 to 6.3 knts on GPS

1simon · « **Reply #19 on:** August 07 2018, 23:05 »

Geoff, i have a standard 3 blade prop on my Ocean 38. And yes, the stern does dig at revs above 2300rm.

IslandAlchemy · « **Reply #20 on:** August 08 2018, 07:41 »

tckearney - your boat is over-propped. The MD22 is a short stroke engine and is supposed to rev a bit. It is not healthy to put that amount of load through the gearbox. Go and look at the torque and power curves for that engine and you will see that cruisng revs are about 2500 which should give you about 6.5-7kts. 9kts and snking the transom should require 3500rpm. To revs for this engine is 4300rpm.