TB deposits

[raz]

I noticed an odd thing when tearing the engine to pieces. The air filter side of the TB's has got some sort of deposits inside. Looks almost like carbon but it's much thinner. It ends right at the butterfly. What the heck is it? There's only filtered air here! Could it be from backfiring? I had a lot of that just after I bought it.

[BRENTTODD]

I see a lot of that in the throttle bodys of multi port injected cars where also it just filtered air also. I wouldnt get worried about it i belive it is oils and other crap in the air. If you have K&N air filters it could be some of the air filter oil. In the car racket we just clean the intake with throttle body cleaner and a old tooth brush collect our money and on to the next not much you are gona do to prevent it from happing it just happens.

 

Good luck and get brushing

Brent

 

PS I do Know how Egr works and the deposits are right on the inlet of air intake snorkles before egr comes into play

[Dan M]

I noticed an odd thing when tearing the engine to pieces. The air filter side of the TB's has got some sort of deposits inside. Looks almost like carbon but it's much thinner. It ends right at the butterfly. What the heck is it? There's only filtered air here! Could it be from backfiring? I had a lot of that just after I bought it.

 

 

It is carbon. It starts as a sort of wet film and builds up from there. Like Brent says clean it & don't worry. It likes to accumulate on the "cold" surface of an intake tract, hence the build up on the butterfly. Low throttle openings, (cold air) coming in + hydrocarbons in the intake = deposits. Nothing abnormal.

[Guest ratchethack]

Raz, if you're running the stock airbox, keep in mind that the crankcase (which has a considerable max/min swept volume differential, so it "pants" pretty significantly, as Pete points out) is vented into the airbox through the spine oil condensor. Slight accumulation of cooked-on residue from condensed oil vapor in the airbox and butterflies is normal and acceptable. Lke the guys said, an occasional wipe-up/cleanout with carb cleaner is good intake hygeine. Notice the accumulated grunge in the throttle return springs around the butterfly shafts below the TBs? Good idea to give those a shot with carb cleaner as well.

[raz]

Will do. Thank you all