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Breva 850: Help! Oil in or around the air box!!

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Prof_Thunder View Drop Down
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    Posted: 18 Jun 2022 at 20:40
I recently posted about my Breva 850 problems, where the breather outlet from the fuel tank seemed to be somehow connected to an outlet from the gearbox - so weird.

So now I have yet another problem. I took the Breva to the nearest Moto Guzzi dealer who said that indeed that was the problem and that they fixed it by modifying the airbox. I was a bit confused when they mentioned the airbox. I know nothing about these engines so I assumed they knew what they were doing although I didn't understand what this would have to do with the airbox.

Unfortunately I was sick so I couldn't ride the bike much after the repair. I've been for a ride today and could still smell oil or oil from the gearbox. I peeped under the tank at what I assume is the airbox and its dripping with an oily substance. I cannot tell whether its engine oil or gearbox oil.

Anyone have any ideas what on earth is going on. I really wish I knew more about these engines. I looked in the service manual to see how everything should be connected in the airtbox but the service manual is actually quite minimalist, the photos are quite poor, and not that understandable unless you know quite a bit of mechanics (which is absolutely not the case for me!).

Any help and advice would be greatly appreciated as I really don't know what's going on.

Cheers.
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2006 Breva 850
1995 Triumph Thunderbird 900
2020 Triumph Tiger 900
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Simond View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Simond Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jun 2022 at 21:05
I think I’d get myself a proper service manual, and work out for myself where the tubes are supposed to be connected, as it seems to me that the “experts” don’t know…, or can’t be trusted.
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Brian UK View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 19 Jun 2022 at 08:46


Wth these you should be able to work out where those  tubes go.
Brian.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote paulbricey Quote  Post ReplyReply Direct Link To This Post Posted: 19 Jun 2022 at 09:52
My understanding (Griso plus looking at Breva blow-by & airbox parts view) is that the gearbox vent pipe should just loop up and then point down, connected to nothing ie just vents to air.

The blow-by system takes 'raw' blow-by gas from the front cover (LHS according to diagram) up to a separator (usually under the steering head on frame eg Griso & Florida - but could be further back). From the separator entrained oil mist is removed and flows back to the rear of the sump - it's usually an emulsion of engine oil/water); and 'mainly oil mist free' blow-by fumes are routed to the air box itself where some mist may drop on the airbox floor & drip down the drain OR seep through the seams where the throttle body rubbers connect OR get burned in engine.

For Griso especially; maybe less for Breva given the swept volume & amount of expected blow-by; if you fill the oil level to anywhere above mid-point of low-max on dipstick, the crank ends throw oil everywhere & you overwhelm the blow-by separator & get lots of oil in the airbox and ultimately into the throttle bodies & the plates get dirty (same applies if your engine is worn). 

So whilst your pipes could be still connected wrong:
1. The gearbox vent shouldn't vent gearbox oil unless it's overfilled itself OR your initial problem allows water/fuel to drain & displace the gearbox oil up & out. i.e. Even if the gearbox vent is connected to the airbox (it shouldn't be), it wouldn't put gearbox oil in there unless it's overfilled.
2. Check your engine oil level & make sure it's at or below mid point on dipstick (when checked properly according to manual to avoid mistaken levels)
3. look inside the airbox door & see how much oil is on airbox floor. If it's loads then somethings wrong BUT some amount may be normal (my Griso always has a small amount). using mirror can also check how dirty your throttle plates are - can cause idling probems (so can idle valve) due to crud & I clean mine every few years.
4. What Brian said..... Check all the vents & drains. Apart from the blow-by separator inputs/outputs described above, idle valve inlet from airbox to idle valve, & two vacuum lines from idle valve to throttle bodies;  all of them should vent to atmosphere AFAIK !!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 19 Jun 2022 at 11:23
I can confirm that overfilling the sump will result in lots of oil in the airbox. The Breva is the same as my Norge.
The oil separator is on the front end of the airbox. The gearbox vent tucks under the inlet to the airbox.

Brian.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Prof_Thunder Quote  Post ReplyReply Direct Link To This Post Posted: 19 Jun 2022 at 12:06
Thanks for all those replies. I will indeed first check the engine oil level and have a look at what's in the airbox. 

I had the impression that the oil on the outside of the airbox is likely to be engine oil as gearbox oil has a funny smell. It didn't smell like gearbox oil.  But I can still smell gearbox oil when the engine is running.

I'll try and check these things out. I would need to take the fuel ta<nk completely off, right, to access the airbox? Or is there any way of peeping in there without taking there tank off?

Hopefully one day, I'm going to have solved all these problems. It's my first MG and when the bike is running, it's a dream to ride. Handles really nicely. Apart from these initial mechanical issues, I really like riding this bike.

Thanks.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 19 Jun 2022 at 12:26
There should be a drain for the airbox, a clear tube with a plug in it below the gearbox. Remove plug now and again to drain the airbox into something.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Prof_Thunder Quote  Post ReplyReply Direct Link To This Post Posted: 21 Jun 2022 at 20:29
I have checked the oil level. I did as stated in the manual, went round the block for 15 minutes then a friend held the bike level while I checked the oil level. Seemed to be at about the middle of the 2 marks for max and min.

I did the oil level check by unscrewing the dipstick and then cleaning it and dipping it back in without screwing it in: Is that right to measure the level? Or should I screw it in?

I didn't remove the tank yet to look inside the airbox and what's connected. However, I couldn't find the clear plastic tube for draining the airbox. Strange. 

As I said there's oily looking liquid on the top of the airbox. I put a paper towel to absorb it and it smelt strongly of petrol.

 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 21 Jun 2022 at 22:47
The drain is a plastic tube about 6mm diameter and it's at the very back of the airbox underneath.
Under the bike, in front of the swinging arm bearing you should see two little tubes. One is the fuel tank vent and filler cap recess drain, the other is the air box drain. This usually has a plug in the bottom to stop oil drips when you don't want them.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gizzmo Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2022 at 17:29
Originally posted by Brian UK Brian UK wrote:

The drain is a plastic tube about 6mm diameter and it's at the very back of the airbox underneath.
Under the bike, in front of the swinging arm bearing you should see two little tubes. One is the fuel tank vent and filler cap recess drain, the other is the air box drain. This usually has a plug in the bottom to stop oil drips when you don't want them.

Unless, like mine, the drain outlet has been snapped off the air box Disapprove by previous owner/dealer
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2022 at 20:02
Been there, mine now has sa brass tube spigot.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Prof_Thunder Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 2022 at 21:24
Sounds like mine probably snapped off at the airbox too since I can't see it. I'll check the airbox at the weekend.


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2006 Breva 850
1995 Triumph Thunderbird 900
2020 Triumph Tiger 900
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