Yanmar 6BY2-260 loss of engine oil

[henningbuus]

A couple of weeks ago while running at max engine RPM, the engine warning light and beeper came on. After slowing down and stopping the engine it indicated low oil pressure. It turned out that the engine had spit out all the oil, and it was now in the bilge mostly on the port side. I managed to pump the oil into a bucket before the bilge pump pumped it overboard. Back at the marina I pumped out the remaining oil from the engine, replaced the oil filter and started refilling the engine. After 12 qts it still did not register on the oil level stick. and again the oil was in the bilge. I have been trying to find out where the leak is. It has to be in the oil pan since it did not show up on the oil stick after adding 12 qts, and it has to be a fairly substantial hole since the cold oil I poured in ran out fairly quickly. I managed to look at the port drain port with an endoscope and the screw was still there, so that was not the cause. It is difficult to get the endoscope under the oil pan and low on the starboard side of the engine. Probably need to lift the engine some to get a good look. I replaced the oil 11 months ago and had no problems until now.
I wonder if anybody has had the same experience or have an idea what failed?

 

[Gin]

Wow - awful! Wish I was writing with a brilliant insight for you. Sorry to say I’m not.

But I did have a knowledgeable and much more experienced friend tell me what to do if I ever see oil in the bilge. To prevent the pumps from pumping it overboard, the advice was to pull the fuse(s) for the bilge(s) ASAP. I’ve never had to use that advice, but I keep it in reserve in case I ever do. It’s a quick and easy way to hold off dealing with the bilge fluid until you have the time or the tools to manually pump out.

Hope you find the source of your problem soon.

Gini

 

[tugnnaweigh]

You’re on the right track thinking you have a big big hole down low low and by low low I mean low low as it’s empted the pan completely and is not allowing it to hold oil in the slightest amount.

I have the same engine and so far have only had to do the manufacturer recall retrofit of two oil lines on the port and these would only leak under pressure is my guess.

Most if not all pans only have a low low hole for the drain plug or in some marine applications this drain plug hole is used for the connection to a permanently in place oil change system typically a hose with a petcock in line. So eyeballing to see if the oil change system needs a shutoff tweak or if the drain plug is securely in place is a good starting point and it sounds like you’ve covered that.

You talk about a “port drain port” and in some marine applications I have seen powerplants with drain plugs on both sides likely for side by side installations which may be what you’re seeing and it’s correct on your part you need to see the other side. A schematic of the engine may reveal all the ports in the oil pan.

Now, here you do have available the “Boatowners Handstand” trunk inverted, fanny in the air, unable to breath, feet waving wildly but it’s usually unsuccessful.

For a somewhat more modern take I would slip clean cardboard underneath all around and have a smartphone running video on each side underneath the back of the engine facing forward while a third person pours in just a liter or less so the stain on the cardboard is localized.

Doing this at night may help you see what’s known in Boating as “way up in there,” I myself often use darkness and a flashlight to help with the initial location of a component or problem and hide my tears.

Also, I would avoid “lifting the engine” any way I could, this will surely cause the aforementioned tears. Think of the engine, transmission, prop shaft, shaft seal, electrical, fuel connections and a bunch of other stuff as a carefully aligned at installation, rusted solid in place bunch a parts that will surely mess with you far far more than you will gain by messing with them.

I did have to repower a Bayliner 2850 that the bottom of the oil pan had just rotted away because the owner had let salt water sit in the bilge and then they bricked the engine so such things can and do happen.

Finally, don’t don’t put the slightest bit of oil into the water especially in a marina, they are rightfully really really on top of any spills and less than a cup makes quite the sheen!

 

[marcham]

Inspection camera are relatively inexpensive nowadays. Probably worth the 100$. I'd start by checking oil lines.

Sent from my SM-T590 using Tapatalk

 

[Brian B]

I would venture to guess that if you can't see a leak of this magnitude it is under the engine. You could have been seconds away from a catastrophic engine failure/seizing. I would have the engine pulled out of the boat and evaluated, time to call in the professionals.

 

[knotflying]

I am more familiar with the 4BY2, but I assume similar configuration. There are several hoses and fittings that feed the oil sensor as well as the turbo. They are low and the suggestion of a scope is a good one.

 

[BB marine]

I believe there are two drain plugs installed in the oil pan of your engine. 1) is located at the bottom of the pan which would drain all the oil. 2) is located at normal oil level on the side of the pan, both port side. When looking for a oil leak in a pan, pan Gasket, front or rear seal in a tight engine compartment. I would clean the bilge the best I could, removing as much water and residual oil as possible. Clean any residue to help false indicators. Then I would use oil absorbent pads. Slide pads under the pan. Start from the front and work toward the back. Sliding pads under the pan from both sides. The pads will show a witness mark of where the oil is dripping. At this point look at a parts schematic and determine if there are any components that could be the culprit, plugs, sensors, gaskets, or seals. Also look for tight clearances between pan and stringer for wear points. Look for evidence of corrosion. The leak you are describing sounds significant and should not be that hard to find.

 

[YukonRon]

We have the Yanmar 4BY2 engine and I was surprised to find that it has a second dipstick on the stbd side of the engine. I'm told it is a leftover from the original BMW block before Yanmar marinized it. It is way down low and forward on the stbd side by the water pump. I wonder if you have one also? It is very low, and I wonder if the tube is attached low enough to drain the pan as you are experiencing if it were to get dislodged? Just it a thought.

 

[henningbuus]

Wow - awful! Wish I was writing with a brilliant insight for you. Sorry to say I’m not.

But I did have a knowledgeable and much more experienced friend tell me what to do if I ever see oil in the bilge. To prevent the pumps from pumping it overboard, the advice was to pull the fuse(s) for the bilge(s) ASAP. I’ve never had to use that advice, but I keep it in reserve in case I ever do. It’s a quick and easy way to hold off dealing with the bilge fluid until you have the time or the tools to manually pump out.

Hope you find the source of your problem soon.

Gini

Thanks for your input Gini. I was lucky to have a handpump and a bucket within reach, so no oil was pumped out by the bilge pump. I agree with you that it is important to know where the bilge pumps fuses are located. I thought the bilge pumps were powered through the circuit breakers, but soon found out the power also bypass the breakers and the only way to really shut them down is to disconnect the fuses. It took some time to locate the fuses One is forward and the other by the Port batteries. I needed to find them so I can wash out the bilge without pumping the soapy/oily water overboard.

 

[Gin]

You're welcome, and I agree completely. The bilge pump fuses on our R27 are inline fuses, near the house fuses in the fuse boxes more generally (in the cockpit seat locker), but separate from them and not necessarily easy to spot. I wouldn't want to have been looking for them for the first time in an emergency. And but for the advice I received, I would not have thought to check them out ahead of time and make sure I knew where to find them quickly.

Gini

 

[henningbuus]

I finally located the source of the oil leak. The engine is made by BMW and Yanmar modified it for marine use. Left over from BMW is an oil pressure sensor located below the oil filter and out of sight. It is not used in the Yanmar application. The bayonet nut that holds the sensor had come lose and since this is right at the output of the oil pump it didn’t take long to pump all the oil out. I got great help from the Yanmar specialist at Harbor Marine in Everett WA. He knew about this deactivated transducer, and he mentioned that it was a known problem with this Yanmar engine. After tightening the nut and refilling with oil I started the engine, and the oil pressure went right up to 61 psi at idle. As the oil heated up the pressure reduced to 21 psi at 122deg F. I didn’t have time to see how low it would go at max temperature. The service information calls for 8.7 to 14.5 psi at 1000 rpm, but does not specify at what temperature. I am crossing my fingers that the bearings are not damaged.