PDQ OWNERS FORUM

Does anyone know what normal oil consumption is for the 100 hp Yanmar engines? I would like to hear from other owners as to their experience. I am looking at one engine that burns a quart approximately every 25 hrs and the other a quart every 40 hours.

I have polled a number of owners and heard numbers from one quart every 100 hours to one every 15. Obviously, the latter one has a yet-undiagnosed problem. If an engine was otherwise running well, I would not get too excited about anything over 50 hours, but that's just my opinion.

When you say "burn" you are saying it is not leaking out anywhere that you can see. If you see a sheen of oil on startup, it could mean oil is leaking past the seals in the oil cooler and dumping out with the raw water exhaust. Another possibility are the oil seals in the turbos. You can check for a leak on the intake air side by removing the cowl ducting air from the turbo to the intake manifold. There should not be any oil in there. A leak on the hot side of the turbo would be harder to find, I think.

There are no visible sign of a leak. The engines have 2000 hours on them. I was told it could be the valve seals. There was a discussion I read about overfilling causing excessive oil use. The engine manual says to check the oil level when the engine is level. In a boat this is not possible. Go figure.

I was told by several reliable folks that when they first got the boat, they were topping off to the upper mark on the dipstick and were dismayed at the high oil loss rate. They claim that by filling beyond halfway on the stick, the "excess" oil is rather quickly lost, but the consumption goes way down if they only fill to the halfway point.

That seemed to be true for me as well, so I never fill beyond halfway. Several others, however, say that is not at all how their engines "behave," so I cannot explain it.

Depending upon where the dipstick is located fore/aft in the engine oil pan, the manufacturer-specified quantity of oil could read as lower or higher (respectively) on the stick when the engine is inclined.

BTW, it seems a lot of folks, like me, have one "good" engine where very little ever goes awry, and one "bad" engine where most of the problems occur.

A previous posting discussed this - due to the engine angle & ??, others (& now myself) have found that if you only fill to the mid-full mark on the dipstick, you may only rarely need to add oil. If I fill to the max, they seem to fairly quickly “burn” down to mid-full, then only a pint or so every 50 hours.

3 years ago when we bought our 2006 PDQ, we had what I considered a serious oil consumption issue on our port engine - at high RPM's, it would consume 1 qt of oil in about every 8-10 hours! It took awhile to diagnose it. Our local Yanmar esperts finally found a gasket that had been compromised inside the oil heat exchanger. It was leaking oil underway. They repaired it and both engines consume roughly the same amount of oil now. I don't know the quantity, but it is quite low on both. I don't worry about it any more like I did back then.

I do not see excess oil consumed when the oil is between 1/2 and Full on the dipstick.

Ortolan wrote: ↑Fri Apr 19, 2019 11:34 am A previous posting discussed this - due to the engine angle & ??, others (& now myself) have found that if you only fill to the mid-full mark on the dipstick, you may only rarely need to add oil. If I fill to the max, they seem to fairly quickly “burn” down to mid-full, then only a pint or so every 50 hours.

This is the same for me. Now I fill it up to about 1/2, like Russ, and I hardly burn any oil.