Engine Exhaust

[brian.webb]

Hello PDQ'ers. I have 100hp engines on a 2006, about 2400 hours total.

I seem to be having what I think is an abnormal amount of blue exhaust coming from my engines, starboard slightly more, but I never noticed it before so I'm not sure. I had a 1000 mile service completed about 200 hours ago, which included rebuilding all of the valves, turbos, heat exchangers, etc.

I check the oil and add any as needed each time I get underway. The first 50 hours or so were great and hardly required any oil, but now it seems like I can take a few hour trip and the engines require 1/4 to 1/2 a quart of oil. And yes, I'm only filling them to half the dipstick level. I also have oil absorbent pads under the engines and there's no leaks.

Is this normal? If not, I was guessing that valves would be the first thing to check.

Thank you!

[duetto]

based on your observation, i'd say it' not normal. you say that it seems both engines are behaving the same way. that complicates things because there is no oil connection between the 2 engines.

you don't mention what the oil consumption was before the service.

imho that's a lot of oil consumption. this may or may not apply. years ago i did a valve job on a car that had quite a few miles on it. at first it ran perfectly but soon the oil consumption went thru the roof. i could never be positive but it appeared that the better valves hurt the oil rings.

i would be talking to the shop which did the work to see what they think could have happened (i.e. oil seal failure).

good luck.

[dstrecker1]

It is possible that the oil is leaking thru the valve guides and into the cylinders. Check to see if the valve guides were replaced. I have been told that the valve guides are the main source of oil leaks on the Yanmars 100s. I have written Yanmar on this when I bought my boat and they were pretty liberal with the oil use. Can’t recall the exact amount but my engine were within specs. What you are seeing may also be leaky injectors. I replaced 4 on one engine and had the ones removed rebuilt and put them on the other engine. It eliminate any smoking I had coming from the engine. Replacing the injectors made a huge difference.

Dennis Strecker
Hull 95

[brian.webb]

Thanks everyone. It's a new boat for me and the very first thing I had done was a 1000 hour service, so I'm not sure what it was like before.

And... I feel like a novice now I was adding too much oil, meaning above the halfway mark. Two issues I've found with my engines when checking oil. What I thought was the halfway mark on the dipstick wasn't. I've also found that when I'm checking the oil I need to check it 2-3 times, and leave the dipstick in for about 5s before taking it out to check. It seems that when I fill it over the halfway mark the extra oil burns off pretty fast, which would explain the extra exhaust. Now that I have the correct level there seems to be a very minimal amount of exhaust.

Thanks for the advice, I'll remember this if I truly do start using a lot of oil.

Brian

[MikeH]

Hi Bryan !

I've got the 75 hp's, so this may not apply to you. I've found that the trim of the boat has an out-sized effect on what shows on the dipstick. When I'm bow down with full tanks, the oil slides forward, showing a low level on the stick. On checking the oil, I leave the dipstick in for a goo 20 count before pulling.

[duetto]

the other thing that is sometimes necessary, always on our boat, is to pull out dipstick (break vacuum?), clean, re-insert, re-check.