jwilson
Well-known member
If anyone else has a Yanmar YM series engine they might like to look at the blanking plug for the alternative side-mounted dipstick hole, which is just under the oil filter. Especially look if you have a very slight oil leak.
The blanking plug on my 3YM30 came out, spraying oil around, and losing certainly over a pint in about an hours running. Until this happened I had no idea this second (unused in yacht installations) dipstick hole was there. I only found it because I went to check the oil level. A previous post on this forum brought the answer from another user who had exactly the same thing happen on the same model engine.
http://www.yachtsnet.co.uk/yanmar-3ym30-2nd-dipstick-blanks.jpg shows the original blanking plug which had popped out, while the engine was running. I found it in submerged in the puddle of oil under the engine. Age (10 years) and probably heat must have hardened and compressed the serrated rubber that holds it in place. On trying to reinsert it after some hours of engine compartment cleanup it was a loose wobbly fit. Neither the local Yanmar agent nor Barrus the importers carried stock of a spare blanking plug, though it is a listed spare part.
Plan A was to glue it back in with some heatproof silicone, but I managed to obtain another new Yanmar dipstick which, when cut down top and bottom, was a good replacement. As belt and braces I put two bolts into unused threaded holes in the block below the 2nd dipstick hole, and wired the sticky-up top spindle down to these.
What is interesting is that this engine has for a couple of years had a very very slight oil leak, a few drips coming from the back of the sump/block area. No real problem as the drips were contained in a moulded-in drip tray, and I wiped up a teaspoon or so of oil a couple of times a year, or whenever I happened to have the engine box off. It had been assumed by both me and the Yanmar agent that this was a gasket leak, but I wonder if this was actually traces of oil leaking past the compressed rubber stopper, and creeping back under the sump only to drip down at the back of the sump. Time will tell......
The blanking plug on my 3YM30 came out, spraying oil around, and losing certainly over a pint in about an hours running. Until this happened I had no idea this second (unused in yacht installations) dipstick hole was there. I only found it because I went to check the oil level. A previous post on this forum brought the answer from another user who had exactly the same thing happen on the same model engine.
http://www.yachtsnet.co.uk/yanmar-3ym30-2nd-dipstick-blanks.jpg shows the original blanking plug which had popped out, while the engine was running. I found it in submerged in the puddle of oil under the engine. Age (10 years) and probably heat must have hardened and compressed the serrated rubber that holds it in place. On trying to reinsert it after some hours of engine compartment cleanup it was a loose wobbly fit. Neither the local Yanmar agent nor Barrus the importers carried stock of a spare blanking plug, though it is a listed spare part.
Plan A was to glue it back in with some heatproof silicone, but I managed to obtain another new Yanmar dipstick which, when cut down top and bottom, was a good replacement. As belt and braces I put two bolts into unused threaded holes in the block below the 2nd dipstick hole, and wired the sticky-up top spindle down to these.
What is interesting is that this engine has for a couple of years had a very very slight oil leak, a few drips coming from the back of the sump/block area. No real problem as the drips were contained in a moulded-in drip tray, and I wiped up a teaspoon or so of oil a couple of times a year, or whenever I happened to have the engine box off. It had been assumed by both me and the Yanmar agent that this was a gasket leak, but I wonder if this was actually traces of oil leaking past the compressed rubber stopper, and creeping back under the sump only to drip down at the back of the sump. Time will tell......
