Yanmar YSE8 blowing oil from breather tube

[okawbow]

Hi All,I bought a 1976 Bristol 24 this year that had set on the stands for an unknown time. (probably 2-3 years) It has a Yanmar 1 cyl. diesel that starts and runs well. However; on 2 occaisions, it has blown some oil from the crankcase breather tube. Once at start up, when it over-reved for a few seconds. Once at full throttle against a 30 knot wind. Last week, I motored several miles at 3/4 throttle, cruising speed, and didn't lose any oil. Any ideas on the cause? Is it time for a major overhaul?Thanks

 

[KorculaChris]

It would seem

as though you either have excessive blow-by which means new rings or a rebore, or possibly the oil level is too high and splash at high RPM is getting to the breather.

 

[Landsend]

test for blow-by...

run motor remove oil fill cap and place hand over oil fill hole...if there is solid pressure against your hand you have blow-by and either have a ring job or a clogged breather system. Good luck.

 

[Bill Roosa]

Check inside the oil filler cap

Not to much to worry about. High RPMs means lots of oil getting pumped. If it can't drain back into the crankcase and begins to accumulate on the head then the normal blow by gases (max blow by at max RPM right) will tend to pick then up and blow them out the breatherCheck inside the oil filler cap to see if there is "engine crud" built up on the head. It should look clean and shiny with lots of bare metal showing. Not all covered with goo and crud.If there is goo and crud then you need to change your oil more frequently than you have been or it is left over from PO.There are several fairly dangerous ways to clean the engine without a tear down but you really have to know what you are doing as they all involve putting flammables in the engine to remove the goo. You can safely take the valve cover off and scrape or make a mess with a brush and kerosene however.

 

[seadaddler]

Check

Do you need to add oil,are you sure it is oil and not fuelIt won't hurt to check the mixing elbo.

 

[okawbow]

Good advice

When the engine blows oil; it happens all at once. It blows out about a pint of oil. I'll check for build up, and change the oil again. I changed oil before launching, and there was conciderable crud in the oil strainer. I've only ran the engine a few hours in all. Anyone know the best oil for the yanmar 1 cyl?Is there an additive that would help clean out the motor, maybe sea foam?Thanks for the help.

 

[okawbow]

Can heeling cause an oil leak?

I sailed the Bristol in a 12 mile race this weekend, in heavy air. We were heeled to the rail most of the time. (we placed 3rd out of 15 or so boats (-:) Before starting the engine, to come into the harbor, I checked the oil. It was down a pint, and oil was in the bilge and next to the motor mount on the breather side. I've used the motor several times since the last oil loss, (also on a heavy air day, as were the other times) with no problems. Has anyone ever experienced oil loss due to excessive heel angle? I also checked the breather tube, and there was a plastic plug in the end. It was loose enough for air and oil to escape. There are also threads inside the pipe. Is there supposed to be something screwed into it? The top of the breather tube is only 2-3 inches above the oil level.ChuckBristol 24"Harmony"

 

[Bud22569]

Breather Baffle Plate Inspection

I have a YSM 12 which I believe is similiar to the YSE 8. On the port side of the engine block there is a cover that contains the baffle for the breather. A hose comes from the baffle plate and over to the intake air silencer pipe. The baffle can be installed upside down which can cause the problem you are describing. If the baffle is installed upside down (or parts of the baffle are missing), oil can be sucked into the intake through the baffle plate (a port heel can especially result in problems of oil getting into the engine intake because of the location of the baffle). It is not difficult to remove this cover and inspect the baffle. You will probably need to remove your alternator and starter, but this is not difficult. Do you have the engine manual for the YSE 8. I may be able to scan and send you a drawing of the baffle on the YSM 12. Also, once the baffle plate in removed you will be able to inspect and clean the oil sump and oil pump suction screen of your engine.

 

[okawbow]

I'll check the manual

I'm not sure the yse8 is set up as you described. I don't think the breather tube was ever connected to the intake. I'll check the manual and parts list for more on the baffle. Sounds like a possibility though. The threads on the breather tube lead me to believe there should be something more to prevent oil from getting out so easily.