Yet another mystery oil leak

[docc]

8 hours ago, Lucky Phil said:

Haven't you just had the engine rebuilt docc? No need for this if the rings seal well. where did the original hose vent to in the airbox? surely on the engine side of the filter. Did it have a reed valve in the original vent line?

Ciao

The GB is equipped with an oil "Separator" attached to the front of the airbox to split the liquid and vapor portions of the crankcase venting (much like the frame spine does on the V11).  From new, the GBs were known to wet the front of the air filter with oil, especially with Grade 2 ("dino") base oils when run hard at high rpm (me!). This was much improved after using a Grade 5, full ester, true synthetic base oil (RedLine). Once I discovered an Aussie racer-type using an open hose to vent the crankcase to the tail cowl above the head, "Triumph-style", I installed the vent on my GB and blocked the separator from the airbox. (Yeah, the GB just got a refresh at 51,000 miles. Plus, I returned to a "dino" oil.)

This all makes me think a couple things about the V11 crankcase venting. Next tank-off, I'd like to inspect the lower banjo bolt and flow through the return line as @Tinus89 noted. Also, I wonder if this wetness @Grim showed us is lessened on V11 running Grade 4 or Grade 5 full synthetics (not the more common faux-synth using Grade 2 base or using Grade 2 "dino" oils. Heat evaporation is significant with these oils and absent with the Grade4/5 ).

[Grim]

2 minutes ago, docc said:

me think a couple things about the V11 crankcase venting. Next tank-off, I'd like to inspect the lower banjo bolt and flow through the return line as @Tinus89 noted. Also, I wonder if this wetness @Grim showed us is lessened on V11 running Grade 4 or Grade 5 full synthetics (not the more common faux-synth using Grade 2 base or using Grade 2 "dino" oils. Heat evaporation is significant with these oils and absent with the Grade4/5 ).

Yeah, I am going to do a change with full-synth in the next few weeks ( and install my Roper plate, woo-hoo), so we'll see if that works. I feel like adding a non-return valve to the vent hose and routing it to the ground would probably be a good thing to keep the airbox clean!

[Lucky Phil]

31 minutes ago, docc said:

The GB is equipped with an oil "Separator" attached to the front of the airbox to split the liquid and vapor portions of the crankcase venting (much like the frame spine does on the V11).  From new, the GBs were known to wet the front of the air filter with oil, especially with Grade 2 ("dino") base oils when run hard at high rpm (me!). This was much improved after using a Grade 5, full ester, true synthetic base oil (RedLine). Once I discovered an Aussie racer-type using an open hose to vent the crankcase to the tail cowl above the head, "Triumph-style", I installed the vent on my GB and blocked the separator from the airbox. (Yeah, the GB just got a refresh at 51,000 miles. Plus, I returned to a "dino" oil.)

This all makes me think a couple things about the V11 crankcase venting. Next tank-off, I'd like to inspect the lower banjo bolt and flow through the return line as @Tinus89 noted. Also, I wonder if this wetness @Grim showed us is lessened on V11 running Grade 4 or Grade 5 full synthetics (not the more common faux-synth using Grade 2 base or using Grade 2 "dino" oils. Heat evaporation is significant with these oils and absent with the Grade4/5 ).

I've run Mobil1 0W-40 full synth group4 oil since day 1 on the original engine and it's never put any oil at all in the airbox.

Ciao