Oil leak oil plug left side engine

[JezzaPeach]

Erwin if it’s definitely that leaking I was thinking of suggesting looking at the CMSNL site as sometimes they state the dimensions of the O rings, but it is not shown for this one. If you measure the thickness and inside diameter with a digital caliper micrometer it could be worth trying a fractionally fatter one. eg if the thickness is say an odd 2.8mm get the common size of 3mm with the same inside diameter (cheap on eBay)
It might just provide a tighter seal? Subject to views of those better qualified than me!

[royhall]

If your sure you have the correct seal and that's undamaged the only other cause is damage in the bore or to the plug. Get a strong light and magnifying glass and check for scores or even a small crack in the bore. On the plug, remove the seal and make sure nothing is underneath it causing a pressure point against the back of the seal. With hot oil at pressure it really doesn't need much damage to cause a leak.

[ka-ja]

I have a parts list that describes it as O ring-9131930000-13x2.5mm

[JezzaPeach]

Ditto. I thought my brake caliper was fine but the groove the seal went in was minutely corroded or discoloured and leaked.

[SeanFD]

Always used paper and a pencil down the plug hole for Triumphs with a mag. Im 68 and still learning

 

That’s how I got started in motorcycle mechanics. I tried to find TDC on a CB125S – my first bike – using a pencil with the inevitable result.

[Erwin83]

Nope, if you run the engine with the alternator cover off that plug will disapear to the darkest, dingiest corner of your garage never to be seen again and a large puddle of oil appear under the engine

So I made a little plate to keep the plug in.
Uuuuunfortunately...

[Erwin83]

Not so much a puddle.. just a good 5 yards of spray, oil on the ceiling, bike's left side covered...

At least no questions about the performance of the oil pump...

[Erwin83]

With regards to the solution of the actual leak.. I found that the plug was snug in the bore when the outside of the plug is around 1 mm deeper than the surface of the cover. That would mean that the oil pressure always pushes the plug out that 1mm, creating a gap between the bore and the aluminium of the plug. As such completely relying on the O-ring for sealing.

I have now placed a small bit of gasket material between the plug and the actual gasket, therefore keeping the oil plug in a bit deeper mechanically.
I also did some better cleaning of the bore and plug.
Let’s see if that does the trick.

[paul G]

 ;

Not so much a puddle.. just a good 5 yards of spray, oil on the ceiling, bike's left side covered...

At least no questions about the performance of the oil pump...

[Bryanj]

This suggests to me that the "pip" on the plug has been shortened somehow

[Erwin83]

This suggests to me that the "pip" on the plug has been shortened somehow

Should it indeed be flush?

[Bryanj]

The "pip" should be flush with the gasket surface, if you look inside the generator cover there is a part of the casting that holds it in, if this pip has been damaged or shortened for some reason the plug will not be far enough in.
I have never seen this happen in 40 yrs but offer it as a possible explanation

[Trigger]

Are you sure that you have a 333 bung as, the 323 bung is shorter  The 323 bung has a depth of 16.50 mm but the 333 is longer .

Also if the bung has been pulled out with pliers, this damages the pip.

[Bryanj]

Never looked closely at the 400 one only the 500/550 so Trigger is probably correct

[Erwin83]

Are you sure that you have a 333 bung as, the 323 bung is shorter  The 323 bung has a depth of 16.50 mm but the 333 is longer .

Also if the bung has been pulled out with pliers, this damages the pip.

I don’t really know. The pip doesn’t look damaged at all. Could I have a 350cc and 400cc bung mixed up? Is that the difference between the 323 and 333?