Carbon build-up after throttle butterfly

[AndyH]

2015 Tourist 1WD with 30,000 kilometers on the clock.
Noticed this recently when I pulled the TB's and wondered if anyone else had something similar - a fix - or a just ignore?
Accumulation in the first picture is less than 1500 kilometers.

carbon1.jpg

Accumulation in the second picture is around 25,000 kilometers

dirty.JPG

Similar pattern on both sides mainly centered around the throttle cable side, or engine side of the TB.
Wipes off with a Qtip dipped in acetone.

Is it a reason for concern?

[Tomcatfixer]

I was getting this quite heavily, enough that it fouled and ruined one of my MAP sensors. I rerouted my engine breather to vent to atmosphere, instead of the airbox, and I noticed a less accumulation. What appears now, I suspect, is blowback from the intake.

[rivers]

Just guessing here but thinking dirty oily air filter from the crankcase vent?

[AndyH]

I was getting this quite heavily, enough that it fouled and ruined one of my MAP sensors. I rerouted my engine breather to vent to atmosphere, instead of the airbox, and I noticed a less accumulation. What appears now, I suspect, is blowback from the intake.

Tomcatfixer - I had been considering a "catch" to maintained positive crank case pressure but hadn't got around to it. There is a smear of oil in the branch tubes, none on the air filter and none in the bottom of the filter box as well as a film on the inlet side of the TB.
Will check the posts here on re-routing the breather (edit found it here viewtopic.php?f=23&t=49981&hilit=breather+crankcase )- I suspect PCV is an environmental thing and the Ural doesn't actually require it? Van never did come back with the official story.

Just guessing here but thinking dirty oily air filter from the crankcase vent?

rivers - Nup.. brand new clean air filter - fitted when I first noticed the problem (see above) but thanks for the thought.

[Tomcatfixer]

I had been considering a "catch" to maintained positive crank case pressure but hadn't got around to it.

Something like this?

2020-01-18 16.11.34.jpg

2020-01-18 16.12.02.jpg

I took Burt1713's idea and ran with it. It works... sort of. Some oil vapor still sneaks by and taints the air filter. My preferred solution is to simply vent to atmosphere.

[Mr Wazzock]

I was getting this quite heavily, enough that it fouled and ruined one of my MAP sensors. I rerouted my engine breather to vent to atmosphere, instead of the airbox, and I noticed a less accumulation. What appears now, I suspect, is blowback from the intake.

I've seen this on cars too. My old R80 had its carb atomizers completely clogged up wth the black stuff. I think you can clean it out, but maybe not entirely stop it.

[AndyH]

Something like this? download/file.php?id=120995&mode=view

Yes, I was thinking of something like that but since my air filter was clean and there was no froth in the air box, I decided against it.
Like Van said, there was a reason they vented the PCV through the box, unfortunately he didn't stick around long enough to tell us why...
If the branch tube distance pieces/spacers are positioned correctly oil won't/shouldn't foul the filter. Having said that if you twist the inlet pipe it will pull the left branch distance piece into the air box (talking from experience here.. lol). I notice on the picture of yours that the right hand "distance piece" is buckled on the front leg - shown in the picture in the original fix post:- download/file.php?id=100214&mode=view?

So back to the original issue, I wonder if the carbon buildup is due to oil misting or something else. I would have thought the inside of the TB wouldn't be hot enough to carbonize an oil film and since it is predominantly on the intake side of the TB, I was more worried about backfiring or ECU issues.
It seems balanced and doesn't show any issues when hooked up to OBDWiz or the dealer tool.

WWID? probably ignore it. So unless someone has any better ideas I might just do nothing.

[Mr Wazzock]

Like Van said, there was a reason they vented the PCV through the box, unfortunately he didn't stick around long enough to tell us why...

Because we're not allowed to drop oil onto the roads anymore.

So it's redirected to the inlets so it can be burnt.

I think in California it came in in around 1980 because that's when the Meriden Triumphs changed to recycling their vented oil. Carburation had to be improved too.

[GHGoodwin]

Carbon or fine particulate dust? Inefficient air filter coupled with oil vapor from CCV. Conical shape in TB going into butterfly would be the perfect place for impingement and trapping.

[windmill]

I have no scientific evidence to back it up, but I believe its just from the carbon deposits in the oil.

[AndyH]

I think in California it came in in around 1980 because that's when the Meriden Triumphs changed to recycling their vented oil. Carburation had to be improved too.

My imported 76 Buick Riviera had PCV and an extra Cubic Inch to make up for it so it might have been the 70's, but I was interested in Vans take on it because the discussion was around how a boxer engine works and the benefits of the PCV.

Topic is exhausted, As Mr GHGoodwin said it is probably just the right spot for deposits and since no one has said omg mine has that too I will just put it down to "it a Ural".
Thanks for all the replies.

[Tomcatfixer]

since no one has said omg mine has that too

I mean, sure, if you don't count the second post in the thread.

[Lokiboy]

Something like this? download/file.php?id=120995&mode=view

Like Van said, there was a reason they vented the PCV through the box, unfortunately he didn't stick around long enough to tell us why...
.

To paraphrase Van and a Ural mechanic, the breather into the air box is designed to do two things. 1. The pressure differential from the cylinders along with the incoming air helps pull the pressure out from the engine crankcase via the breather. 2. The atomized oil is there to provide oil to the front end of the piston and working parts in the carburetors (not sure if EFI have moving parts?)

Anyway, that’s how I remember two different conversations from folks vastly more qualified than me stating the same thing. Take it for what it’s worth.

[AndyH]

I had been considering a "catch" to maintained positive crank case pressure but hadn't got around to it.

Something like this?
2020-01-18 16.11.34.jpg
2020-01-18 16.12.02.jpg
I took Burt1713's idea and ran with it. It works... sort of. Some oil vapor still sneaks by and taints the air filter. My preferred solution is to simply vent to atmosphere.

Seems Ural took Burt1713's idea and ran with it from 2017 onwards

EECS.PNG

[Tomcatfixer]

Would'ja look at that!