Throttle Body Varnish Build-up

kutu · January 15, 2008

Are you noticing a build-up of that sticky substance in the throttle body that causes the throttle plate to stick when first coming off idle? Do you think that a PVC "catch-can" would help prevent this build-up?

I checked my 2007 SD the other day and the sticky residue was there so I cleaned it.

In the past, I have seen this on my 1999 Sierra and on a 4wd 2002 Yukon, both had the traditional cable throttle control. It caused the trucks to surge when first appling the gas. I started cleaning the body with an acetone soaked rag periodically to cure the problem. On My 2002 2wd Yukon the varnish did not seem to effect the "drive-by-wire" system as much, but the sticky stuff still built up.

dlstewart01 · January 15, 2008

Some where around 2002 or 2003 they went to a fixed orfice PCV. These lets a lot less oil into your intake. And they enter in the middle of the intake so no oil is going through the throttle body. Make sure you are using good gas and have a clean air filter. Now on the later trucks you may see a pipe connection at the throttle body, this is not a PVC but a fresh air tube. No oil should be in this tube.

I run an AMW catch can. These are not cheap but have a filtering system and really work great. There are a few others out there that actually filter.

The ones on Ebay for 10 or 20 $ are empty cans and in my opinion don't do much.

Have a good one,

Don

Draenor · January 15, 2008

Its common for it to occur. I have cleaned twice since I bought it in '04. I thought about a catch can, but due to the lack of it occuring, I thought I'd save myself some money.

ewiski · January 15, 2008

i have to clean mine about every 20,000 because of this.

asilverblazer · January 15, 2008

Hope it doesn't burn up the motor that opens the throttle blade because of the extra resistance.

dreman · January 15, 2008

I cleaned the throttle body on my '99 just like you did, but I've only cleaned it twice since new. I cleaned it once at about 25,000 miles and then again at about 75,000 miles. I'm now at about 275,000 miles and haven't needed it since.

cmoore74 · January 15, 2008

Never heard of the catch can until now and it is interesting. I noticed after ~20k miles I've got the typical varnish and soot inside the thotle body building up, but I can't be pulling that much oil because my oil level never drops between changes.

One question comes to mind: Is it necessarily bad to have a little bit of oil vapor in the intake for added lubrication?

Just thinking maybe your better off not using a catch can and just cleaning the intake as required.

Thoughts?

dlstewart01 · January 15, 2008

Never heard of the catch can until now and it is interesting. I noticed after ~20k miles I've got the typical varnish and soot inside the thotle body building up, but I can't be pulling that much oil because my oil level never drops between changes.

One question comes to mind: Is it necessarily bad to have a little bit of oil vapor in the intake for added lubrication?

Just thinking maybe your better off not using a catch can and just cleaning the intake as required.

Thoughts?

Oil in your intake means oil in the cylenders during conbustion = carbon = not good.

Don

kutu · January 16, 2008

The website below has some info on catch cans.

http://eliteengineeringusa.com/Catch_Can_GP.html

1999 Tahoe 4x4 · January 16, 2008

...I started cleaning the body with an acetone soaked rag periodically to cure the problem...

I'd be careful with that acetone. I clean mine with regualar carburator cleaner. Next time I plan to take it off and really clean it well. On my 1999 there is an IAC Valve. If your new trucks have that (which I'm pretty sure they must have) it is a good idea to clean that as well, while you are at it.

cmoore74 · January 16, 2008

Never heard of the catch can until now and it is interesting. I noticed after ~20k miles I've got the typical varnish and soot inside the thotle body building up, but I can't be pulling that much oil because my oil level never drops between changes.

One question comes to mind: Is it necessarily bad to have a little bit of oil vapor in the intake for added lubrication?

Just thinking maybe your better off not using a catch can and just cleaning the intake as required.

Thoughts?

Oil in your intake means oil in the cylenders during conbustion = carbon = not good.

Don

Don,

I like the idea, but how much oil is really going into the intake? Can you give us an idea as to how much oil is collected over a certain number of miles? Also how hard do you drive your truck (lots of snappy accelerations and let of the gas, conservitively, or somewhere in between)? Do you have noticable oil consumption?

I noticed my past GM's with multi-port (aka vortec) got dirty quick and I'd love to prevent that, but sounds like maybe the new fixed orifice PCV may not be letting nearly as much oil into the intake. With my '06 there is no noticable oil consumption between changes (starts at the top of the fill line and is still there 5k-6k later).

Not trying to start an argument, I'm actually trying to decide if it is a worth-while mod for me.

Thanks,

Chris

dlstewart01 · January 16, 2008

I drain the oil from my catch can every 6 to 7 hundred miles. There is about 1/4 inch of oil in the can. I don't know a couple of ounces maybe, but any is too much for me.

Don