Oil Leak - Yanmar 2GM20F any ideas !

[TeamSpirit]

After enjoying a pleasant weekend away with No 1 son with 34 mackeral under his belt today. Inbound from the nab my oil pressure warning blipped.... checked but nothing untoward found so made way .... got to marina channel reduced speed and ear drums where blasted - checked below again this time about 1/2 litre of oil in sump beneath engine, can't see the source but dripping seems to be from the front end under the main pully but just can't see without dismantling panels.
Checked useless manual but waste of time. Have annual fortnight coming up in July so need to urgently get this sorted. Has anyone had similar experience or can suggest a what the cause may be?? and is there a manual thats up to the job !
Ta

 

[savageseadog]

Have you got your dipstick in properly?

 

[jerryat]

It's possible it's the front end bearing, though these don't normally suffer catastrophic failure, and in any case would be well above the oil level in the sump so would only leak while the engine was running. Did you check to see if any oil was coming out when the motor was stopped?

Have you checked the oil filter to ensure it's fully tightened? I know it sounds weird, but that 's exactly what caused a similar gush of oil (over several hours) on my brand new engine last year. Nearly had a heart attack before I realised they hadn't done it up tightly!

No damage done, as it looked a lot more than it was.

Could it be an oil seal gone in the water pump assembly? I don't know your engine, but if it's leaking there, it might run down to the pulley area you mention.

 

[davidbains]

Happened on my 2GM20 and I traced it to a corroded oil pressure pipe leading from the filter area externally up to the back of the rocker box. Easy to replace once you've removed the starter motor. Using an articulated mirror from an auto shop makes searching easier.
I assume the oil only appears when engine running. If it drips all the time consider a corroded sump.

 

[TeamSpirit]

Thanks All - on further investigation it appears that the oil drip is seaping out at the face of the block below the main pully slightly to port.
It looks like a gasket of some sort may be seaping, someone mentioned problems with the design of a Yanmar gasket which has been improved... but don't know specifics.
Cor do I wish it where a straightforward as dipstick!
Any pointers ????

 

[Oldhand]

It sounds like its from the bottom of the timing gear cover which is bolted onto the front of the block with a gasket seal. If so it can be cured by getting the area clean and dry and applying Thiokol selant liberally on the outside of the joint, see: http://www.polyspec.com/technologies/THIOKOL.htm. However, it may make removal of the timing cover more difficult in the future.