Yanmar 2GM20 Shoots Oil Out Dipstick Hole

[Chief Engineer]

Valve guide seals

[Maine Sail]

Originally Posted by boden36

I may have missed it above, but have you checked your engine breather? A buildup of crankcase pressure through inevitable small amounts of blowby will exit through the dipstick tube if there is nowhere else to go.
Regards,
Richard.

Amen, check the simple stuff first.... Crank case pressure and a weak o-ring seal on the dip stick can cause this..

[sailorchic34]

+1 on the crank case vent.

[delmarrey]

I believe the crank case vent (Diaphragm Assembly) is on the maintenance list for replacement every so often. On the 3JH it is every 1000 hours.

[Sonosailor]

Well, I can add that, after replacing the bad lift pump with the tested original, and after cleaning up the mess, we have not had the problem again. Sooner or later, as nothing else is changed, the problem will repeat, with the stick jumping out and the oil shooting into the bilge. For now, the oil in the crankcase is not growing. The engine has run at least 10 hours since the last fiasco.

[gjordan]

Another of life,s messy little mysteries! Keep us posted if you get a solution. Good Luck .____Grant.

[Sonosailor]

Update at end of season:
Never again did I grow crankcase oil - That only happened with the bad lift pump from FredMarine in Pte-A-Pitre. Also note that the breather on the 2GM20 is just 3 empty chambers - too simple to clog.

I told the whole story to a mechanic here in Chaguaramas, Trinidad; who said that it was probably my rings getting stuck, but he doesn't know why it "healed itself". I told him the rest of the story, including how I installed a lift pump with an obviously bad diaphragm, and had tightened the dipstick with a tiny bit of tape - and how the fuel filled the crankcase, ran through the breather to the air intake, and the engine "ran away". He said "That's It!"

He says the diesel in the crankcase cleaned the rings and many other potential causes, and that is why the problem stopped. The use of PB Blaster probably would have done the trick, as would have adding kerosene to the oil, but diesel works rather well.

He went on to ask if I am loyal to one brand of oil, and I said no - he said that caused the problem - Some brands use silicone-based lubrication while others use teflon-based lubricants; and the two, when combined, create a gum that can stick up the rings.

I'd love some input on this business of mixing oils. I've always heard people recommend sticking to one brand, but nobody ever gave a reason. Is this it?

[delmarrey]

I'm no expert on oils but I do know mixing can be a problem, but which I ones, I'd have to research.
As for sticky rings, several things can contribute to that. One, being in storage for a long time (relative), and old oil that has been dirty for a long while. Another would be too much blow-by.

But yeah, diesel makes a good lubricant/rust braker. When I was a wrecking yard engineman (1968) we use to take the seized up motors that the rain had gotten into and rusted the cylinders and pull the plugs and fill the cylinders with diesel and let'm soak a couple days. Then start working the motor back and forth. Sometimes it would take a couple days but eventually they would finally rotate.

Then cranke'm over, with the starter & the plugs out, for a couple minutes. Put the plugs back in and start'm up and brake them in. One of those motors my Boss put in his race car and won that race (a 348 cu. in. Chevy). The rings would always seem to reseat themselves in a short time.

[Irish rambler]

If anyone has a Ford with a similar problem it is usually the diaphram on the lift pump, or, the injector leak off pipes which run between the injectors inside the rocker cover, they are a brased joint and sometimes crack at the brasing, letting the excess injector fuel run via the rocker lubrication drain holes back down to the sump..
Hopefully this will help someone..

[Sonosailor]

I've had some discussions with oil experts, including an email exchange from an engineer at "Total Lubricants", and he told me that my mechanic who talked about silicon and teflon additives and their mixing, is pretty much misinformed.

The most common advice was to get the oil recommended by the manufacturer of the engine, or an oil with an even higher API number, and change it at reasonable intervals so that it is as clean as practical. Also, run the diesel at reasonably high rpms as often as practical to minimize carbon in the cylinder.

I apologize for mentioning his name here, as he is being as helpful as he can be, and can definitely do the work and get the parts for those of us here. I'll ask a moderator to go in and remove his name.

[Irish rambler]

If I may respectfully add a little to the blog, if you run a compression ignition engine(Diesel) at low revs on a light load it will not reach it's proper operating temperature and the unburnt fuel will wash the oil off the cylinder walls causing premature wear, the exhaust will be smokey, this will leave oily sooty deposits around the exhaust valve gear and will clog up the vanes on turbo's. Secure the boat fore and aft when charging batteries and run the engine under load in gear, diesels really thrive on hard work. Only use the recommended oils (that's why they are recommended by the engine builder) and change according to the service manual.
Keep it simple RTTFM refer to the ? manual.
Many marine diesels have to be rebuilt prematurely because of poor operation and 35 years plus is not uncommon for a well maintained engine.
I hope this helps someone.

[Cheechako]

I agree with that.... what confuses me though is all these old sea water cooled volvos and yanmars that just seem to keep running up here. 30 years isnt uncommon. the damn things never warm up in our 50 degree water..... not even that hot to the touch when running....

[westwinds]

Diesel is really thin oil and I wonder if there is any chance of bearing and/or cam lobe failure from inadequate lubrication from lack of adequate film strength. If you still have some of the diesel and engine oil mixture, send it in for an oil analysis for metal particles. If no mixture is left, run the engine with new oil and then do an analysis. I hope I am just being a pessimist here, but bearing failure can result in catastrophic failure of crankshaft and/or connecting rod journals with a spun main bearing and thrown rods. Better to catch the problem early.

[Irish rambler]

Yes Cheechako you're perfectly right those old engines will definitely run, but indefinitely. As you know leisure marine diesels never really get used to their full potential in the majority of boats. I'm a great believer in keeping everything in the boat ship shape and Bristol fashion, not to be a pain in the ass but as it's not only my home my life has depended on my Perkins performing faultlessly more than once one in the past, I love this old world and plan on being around a good bit longer to crack a few beers with some of you guys.

[wanderer1]

Hi,just went though the same problem with my 2qm20 .The crankcase ventilation was plugged solid.Took off the ventilation door,cleaned it up with break cleaner and put a new hose on that goes up to your air intake and it fixed the problem,hopefully also fix yours.