so i pulled the throttle body off yesterday and when i looked at the inside of it i noticed a large buildup of what i assume is carbon. just a thick coating of black carbon on the inside to the TB and on the inside of the intake manifold. now i'm guessing that some buildup is normal, but i dont remember the buildup being this bad the last time i pulled it off. any ideas as to what would cause such a build up? i know that i pulled it off about a year ago to change the intake manifold gasket and cleaned it all up to sparkling new that day. hmm...? thanks for the info.
dave

 

It's probably normal. I would check your intake for any leaks and also replace the air filter if you have not done so recently. Use some carb cleaner (AutoZone, etc.) to clean your TB.

 

well, ill be pulling the intake completely off this time around. so i guess that wouldnt really matter now. as far as the air filter, i have a moroso cai that i clean pretty regularly. would using too much oil after cleaning somewhat cause this? ah well. i guess i wont worry about it too much then. thanks for the advice.

 

Out of curiosity, what type of filter did you have?

 

hey yea to much oil can make a mess it can throw off your maf reading too...

 

i just use the oval shaped moroso filter that it came with. i usually clean it with the k&n cleaning kit anyways. after i clean it up this next time, ill have to not use so much oil. thats probably part of the problem then.

 

I could of guessed it was a K&N

Personal recomendation... just use a paper filter and change it with every oil change (their very inexpensive). I had this problem on my other car (olds delta 88) and i can show you pics. I cleaned it up and havn't had any build up as of yet since i did it (switched back to a paper filter). I'm still reseaching it, but i want to say almost all K&Ns will have this problem. Just don't have enough proof yet.

I have pics of the TB off my olds. It was nasty. I'm thinking that the oil that goes into the TB and manifold, helps the carbon (or any other substance) stick to it. So i'm not saying you won't get any sort of buildup without a K&N (just to clear things up).

Oil wasn't ment to go into your intake anyway, and i feel with a oil based air filter, its hard to prevent that. Just my .02

 

A common source of carbon buildup in the LT1 TB is the air supply line that runs from the throttle body to the passenger side valve cover. This line is intended to SUPPLY air from in front of the TB blades to the valve cover, where the air is pulled through the engine by the PCV system. Normally air flows only from the TB to the valve cover.

But, if you have pressure buildup in the crankcase, the crankcase vapors will vent out the valve cover, through the line, and blow oil into the throttle body. Excessive pressure in the crankcase can be caused by a plugged PCV valve (easy to check), or excessive blowby on the rings. Pull the oil fill cap off and listen at the fill tube for a "chuffing" sound, or air puffing out of the fill tube.

Then pull the top cover off the TB, and look for oil buildup in the top of the TB. That's where the passage from the nipple on the side of the TB connects to the passage to the hole in front of the blades.

 

Injuneer has it down for ya. I'm glad he typed all of that instead of me

-Shannon

 

OK. Say that is the case. What do you do to fix it?

 

Rebuild the engine to reduce blow by It's honestly not hurting you. You may want to try changing the top plate gasket and switching to a valve cover breather and plugging the throttle body hole. Mine is like that. I get blowby, but things are clean

-Shannon

 

What size cap do you need to plug that hole in the throttle body?

 

You can put a filter into the route between the valve cover and TB.

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