I went to autozone to get a filter, and a Vaccuum cap for the TB. I picked up both for about $4.50.

My question is will this hurt anything If I do this? I want to bypass it because I removed and cleaned my throttle body a few weeks ago, and it had alot of grime in it from this tube. SO I figured that doing this would buy me some time between cleanings, and reduce the crap spit into the intake.

Thanks!

 

it serves as some type of crank vacuum (correct me if I am wrong), my dad said don't do it, but other LT1 owners say its fine. I haven't had any problems with it. I also figure its sucking that hot air from the valve cover, so can't be helping any in performance, + all that oil that is sucks up. I am thinking it was put there for a purpose, but why did GM put that line on there without sometype of filter? I mean all that oil going into the intake can't be helping anything?

 

What that is doing is reducing blowby---meaning you have pressure within your crankcase and the tube/pcv going into the TB causes a vacuum suction which reduces blowby that affects the ring sealing. You can bypass it if you want but I wouldn't personally.

 

The purpose of that tube is to supply clean, filtered, MAF metered (94 and up only) air from IN FRONT OF THE TB, to the valve cover. From there, the PCV system pulls the air through the crankcase, and lifter valley and out from under the bottom of the intake manifold, and dumps the air and vapors from the crankcase into the inside of the intake manifold, where is is burned as part of normal combustion in the cylinders. Since the air is "metered", the PCM allows for this in the air/fuel calcs.

If you remove the line, you need to add a "breather" to the valve cover, to let air into the PCV system, in effect creating a small vacuum leak. The PCM should be able to correct for this "leak" with long term fuel corrections.

If you have excessive oil in the tube, or the TB, it could be because the PCV valve is plugged up. Or, you have excessive "blowby" of combustion products past the rings.

 

Fred: It would be for the 93 so it still as usful on non-mass air cars?

 

Injuneer,

I have a related question. When I added the Hot Cam/kit, I changed valve covers to GM chrome ones. Each vc has an opening for either a cap or breather and I use breathers w/ filters on both sides. Would this effect the "metered" air coming into the crankcase and if so, what are the ramifications?
Thanks!

 

The 93 just eliminates the "issue" of the vacuum leak. If the engine is in good condition, and the PCV valve isn't plugged up, there shouldn't be any flow back through the tube. When I pulled my engine out for the stroker rebuild at 65K miles, there was no sign of oil in the TB.... clean as new.

If you do get enough blowby to overpressure the crankcase, a breather is just going to let the oil film blow all over the engine. Some people claim the breather will help avoid the intake manifold oil leak, but I'm not convinced on that one.

There is no advantage to "opening up" the PCV system, and with a 93, there wouldn't appear to be any disadvantage.

 

It opens up the PCV system. Technically, its not legal because its an "emissions" system.. but nobody seems to care much about that.....

You will have unmetered air entering the crankcase, and then into the intake manifold. The PCM will not see that air, and at idle and low load (high vacuum), it will cause the long term fuel corrections (BLM's) to increase slightly. At WOT, when vacuum all but disappears, it will do little, if anything.

If you have a blower, you either need a breather or a way to recycle PCV vapors to the blower inlet.

I run an (almost) 800HP nitrous motor, and the PCV system is still intact, no breather.

 

Now i could have sworn the reason for a pcv or positive crankcase ventilation system was two things; to introduce the vapors from the crankcase into the intake for combustion and also 2 create a positive seal for the rings. In drag racing they put the pcv and connect it to the collector to create vacuum to literally "suck" the blowby out for better ring sealing. I guess the bad part is your engine compartment is going to smell lke oil and other gases and the good thing is your TB will be clean but I use it because it doesn't hurt anything to keep it

 

What if you just put a filter inline?