Overfilled MD2B caused oil leak

[Scubaseas]

OP states: "When we checked the dipstick again we saw we were just a little over the top marking," This is not going to cause runaway or blow out the seals. You can run a MD2 with more than an extra quart in it and not have it over pressure the crank case or vent back into the engine causing catastrophic failure by runaway. This is not a runaway engine scenario so let's not run around with our hair on fire about it.



From all sounds of it he's either got a dipstick leak (really common on this motor) or a leaking oil pressure switch. As the dipstick is closest to the flywheel and any oil leaking there will get pulled toward the crank pulley and then spray oil all over the place I would look here first as it meets all his symptoms stated. The oil dipstick sits on top of the oil pressure relief valve and while not under direct line pressure it will leak like a sieve if loose or without a rubber sealing washer on it. Ditto it will leak badly if the relief valve that holds the dipstick is loose in the block you will have line pressure oil leaking straight towards the flywheel.

[newhaul]

Originally Posted by EZ Breezy

Hi everyone,


I'm new here, but I hope this community might be able to give me some useful tips along my journey to the crusing life.

During the delivery of our new (but old) cruising yacht, we noticed the oil level of included Volvo Penta MD2B was a little low, so we decided to fill her up. When we checked the dipstick again we saw we were just a little over the top marking, but as we had no way of getting it out en route and not knowing that much about engines, we decided there were worse problems than a little to much oil...

When we continued along our journey home, at one point the engine wouldn't start, but I could hear the belt from the starter engine slipping, so I check the engine compartment and it was almost completely covered in oil. I quickly cleaned the belt and started the engine again, as we were entering the final leg of our route which is a high shipping traffic area. We got to our home port safe and sound, but upon further inspection today, we had to clean out almost 3L of oil out of the bilge, and the dipstick showed literally no oil remaining, so I assume everything has leaked out somehow.

I poured in a little oil today to check tomorrow wether it has leaked while not running, and if that turns out to be the case I was hoping to get some tips on which parts to check, since they would be the first to fail when oil pressure is too high as a result of overfilling.

I've read in the service manual that there should be a valve in on of the engine components which protects against high oil pressure by letting out excess oil, but it seems to me that should have only let the excess oil out, instead of dumping everything.

Any suggestions are welcome, and if you think we just ruined our engine, please be gentle.

A few things are you sure its an md2b? You said the belt on the starter was slipping which leads me to believe its an md2 with a dynastarter. There is an oil over pressure safety but that takes well over 60psi to trigger. There is no crankcase vent on this unit. ( md2 or 2b now with oil on the dynastarter belt i would say its most likely the front main seal that is leaking . Not difficult to replace but does require some non standard tools .
There is no drain plug in these engines. So thats not the issue. Most likely not over pressured but just a real bad front seal .

This should help you some its for the md series
https://www.google.com/url?sa=t&sour...zP2gdkFTc-80Kv

[Scubaseas]

An MD2, 2B, 2C, 2D engine vents through the oil fill cap (#21). The op SWITCH or monitor switch is normally open and closes at about 8psi. I would advise checking o-rings #11 and #8 and tightness of #10





Al
Retired Certified Master Mechanic, former ABYC member, Owns a boat with an MD2B

[Cadence]

I would hazard a guess you over filled to the point of the crank vent was blocked and enough pressure built up to blow out a significant amount of oil.

[EZ Breezy]

Originally Posted by Scubaseas

From all sounds of it he's either got a dipstick leak (really common on this motor) or a leaking oil pressure switch. As the dipstick is closest to the flywheel and any oil leaking there will get pulled toward the crank pulley and then spray oil all over the place I would look here first as it meets all his symptoms stated. The oil dipstick sits on top of the oil pressure relief valve and while not under direct line pressure it will leak like a sieve if loose or without a rubber sealing washer on it. Ditto it will leak badly if the relief valve that holds the dipstick is loose in the block you will have line pressure oil leaking straight towards the flywheel.

Thanks, I think this is indeed the most plausible scenario, as we didn't have any problems before the refill, and my gf isn't sure she screwed the dipstick on super tight. We filled it up to the appropriate level today and had it running for a few minutes to check wether there was a clear leak but to no avail, so I guess this might have been it! We did manage to get a friendly mechanic to swing by tomorrow before we have to move, so he'll be able to tell for sure probably and explain some things for us.

[Scubaseas]

Originally Posted by Cadence

I would hazard a guess you over filled to the point of the crank vent was blocked and enough pressure built up to blow out a significant amount of oil.

Good point. On the MD2 you need to go over two quarts before this is an issue. Depends on the angle the engine is at but it is also possible that either the lift pump diaphragm leaked into the sump or the injection pump is leaking into the sump causing the engine to be over filled and then "threw up". You should see a lot of oil around the oil filler cap and the air filter that has the hose attached if this happened. The engine vent is 2/3 the way to the top of the engine and well baffled. If the above leak diesel into the crankcase scenario is correct you should smell diesel in the oil and it will "feel" thinner as the viscosity of the oil is reduced by dilution with the diesel fuel.

[Scubaseas]

Originally Posted by EZ Breezy

Thanks, I think this is indeed the most plausible scenario, as we didn't have any problems before the refill, and my gf isn't sure she screwed the dipstick on super tight. We filled it up to the appropriate level today and had it running for a few minutes to check wether there was a clear leak but to no avail, so I guess this might have been it! We did manage to get a friendly mechanic to swing by tomorrow before we have to move, so he'll be able to tell for sure probably and explain some things for us.

Just needs to be tight enough. Not super tight, not 1/2 turn before it breaks tight. About as tight as a soda bottle screw cap is fine, Hand tight, no tools.



You might want to check the oil level every 15 to 20 minutes when motoring until you find out if you have a problem or not. I'd also do a sniff test on the oil now and after you have run it to make sure it's not getting thinner or rising in level and smelling more and more like diesel.



Make your job easier for the mechanic and clean the motor off. Your dime is based on his time. Get some brake and parts cleaner or carb cleaner/gum cutter and spray down the engine especially around the dip stick, the thing with the four little holes in it that the dipstick screws into, the oil filter and that hexagonal thing with the blue wire going to it. Take the air filters off as it makes it a LOT easier to get access, especially to the dip stick. Don't huff the fumes, ventilate well. Don't do the cleaning while it's running or spray into where the air filters attach to the engine. Both of these cleaners will evaporate and are not going into the water/environment like Gunk engine cleaner and a water wash. You can't find oil leaks if there's oil every where. Simple Green is pretty effective on cleaning up the oil that's everywhere. As are baby diapers and oil leak pads. Dawn dish wash detergent works in a pinch.



Once the engine is clean use a finger or paper towel to look for fresh oil. Remember gravity makes oil fall. So look above where you see any oil. If it only leaks when it's running that narrows down the possibilities. Another method is sprinkle talcum or baby powder on the engine and below it as it will make finding drips a lot easier. Another and very effective method is introduce a fluorescent tracer dye into the oil and then use a back light/UV source to see where your leaks are. Down side to this is if you don't carefully watch the engine for where the leak starts you may get so much leaked out that you need to re-clean and start over.



If you don't see a leak at idle tie up to a dock or back down on the anchor and run the engine under load in gear. Your oil pressure at idle is less than when running at 3/4 to full throttle. From the sounds of it you have a leak only when it's running. Some oil leaks will not leak at idle but will at full throttle.



Good luck.

[newhaul]

Originally Posted by Scubaseas

An MD2, 2B, 2C, 2D engine vents through the oil fill cap (#21). The op SWITCH or monitor switch is normally open and closes at about 8psi. I would advise checking o-rings #11 and #8 and tightness of #10





Al
Retired Certified Master Mechanic, former ABYC member, Owns a boat with an MD2B

Sorry but disagree with how they fill and vent .
The first picture shows the dipstick and pressure sensor .
The second shows the oil fill plug on top of the md2 rocker cover.

[Jono as 2234]

Just slightly off topic, but I have always worried about the accuracy of the dip stick. Shaft drive boats have the diesel at an angle, so unless the dip stick is exactly central to the sump, it must be inaccurate???

[newhaul]

Originally Posted by Jono as 2234

Just slightly off topic, but I have always worried about the accuracy of the dip stick. Shaft drive boats have the diesel at an angle, so unless the dip stick is exactly central to the sump, it must be inaccurate???

The manufacturer actually takes the angle of install into account

[Scubaseas]

Originally Posted by newhaul

A few things are you sure its an md2b? You said the belt on the starter was slipping which leads me to believe its an md2 with a dynastarter. There is an oil over pressure safety but that takes well over 60psi to trigger. There is no crankcase vent on this unit. ( md2 or 2b now with oil on the dynastarter belt i would say its most likely the front main seal that is leaking . Not difficult to replace but does require some non standard tools .
There is no drain plug in these engines. So thats not the issue. Most likely not over pressured but just a real bad front seal .

This should help you some its for the md series
https://www.google.com/url?sa=t&sour...zP2gdkFTc-80Kv

The engine has to vent somehow no matter if its a MD2 or later. The MD2B,C,D vents through the oil fill cap which itself is mounted on a housing bolted to the timing cover. In your picture that has the air filters, pull back the tarp to the right and what's under there? There is a bracket/housing next to the injection pump that's bolted to the gear housing/timing cover. What's on top of that housing? I repeat you have to vent the engine somehow. If memory serves there is a pipe that runs from the timing cover/gear cover or there's a hose coming out of the oil filler cap. On MD2B or later it's a hose out of the oil cap. The MD2 maybe a vent pipe out of the timing cover.



If the OP has a picture of his oil filler that would solve the question of what engine he has.

[Scubaseas]

Newhaul,

This is off the MD17 parts catalog but it's the same set up on the MD2B,C, D. #31 and #35. #35 bolts onto the timing cover/camshaft gear cover next to where the Injection pump is mounted. I am not arguing with you other than a motor MD2 or not has to be vented. I would guess also off the timing cover going somewhere after that. You simply can not have an engine that is unvented. You'd blow out the seals or any gasket exposed to the crankcase pressure areas. Vent should be abut 13mm or more.

[roverhi]

Assume you have the dynamotor starter/generator which explains the belt slipping after the oil bath. A little extra oil wouldn't cause your problem. Since you got the engine started and it ran fine except for the oil leak, the fix shouldn't be expensive. Sounds like you have a leak in the pressure oil system. Been a long time since I had to deal with an MD2 but would check any external lines as they can rust out. Restart the engine after refilling the oil while carefully looking for a source of the leak. Don't run it for long if the source of the leak isn't readily apparent. To be super safe might even just turn the engine over with the compression releases actuated and see if you can find the leak.

[Scubaseas]

Newhaul,


Here's a diagram of the MD1 early style, Same as the early MD2 style, Note please that both oil fill caps vent the engine. The later oil fill caps simply pipe the vent gas to the air filter or out a engine vent or PCV pipe. Note #31 is a "breather cap". On the later motors they lost the hand crank and put a oil filler tower on it and ran the crankcase vent/ PCV system through the cap and into the air filter. You can fill the early style engine through the #31 breather cap or oil filler cap.

[newhaul]

Originally Posted by Scubaseas

The engine has to vent somehow no matter if its a MD2 or later. The MD2B,C,D vents through the oil fill cap which itself is mounted on a housing bolted to the timing cover. In your picture that has the air filters, pull back the tarp to the right and what's under there? There is a bracket/housing next to the injection pump that's bolted to the gear housing/timing cover. What's on top of that housing? I repeat you have to vent the engine somehow. If memory serves there is a pipe that runs from the timing cover/gear cover or there's a hose coming out of the oil filler cap. On MD2B or later it's a hose out of the oil cap. The MD2 maybe a vent pipe out of the timing cover.



If the OP has a picture of his oil filler that would solve the question of what engine he has.

no vent pipes on the md2 it vents the crank case back up via the gallery oil return the only other thing under the tarp is the westerbeke10-two that is going in my boat instead of the md2 . half the weight and fwc so no brainer there.

as to the op's md a picture of the top of the engine will solve the what model question . the md2b will have head bolts visible on the air intake side the old md2 only has 4 dead bolts and 2 are under the rocker cover.