TB - What is the 3rd Hose Function?

[SuperG]

Well, now that I understand the basics behind the Throttle Body (thinks Rangerj!), I see I am missing something...I can easily identify the in/out tubing and ports for the coolant, however, what is the other, larger tube for? It has quite a bit of gunk inside that port...

Thanks for the help!

 

[SHOZ123]

That hose sucks the blowby gasses out of the engine through the oil separator under the intake. There is also a hose that goes from the rear/front side of the TB to the front valve cover, this is the PCV make up air supply hose. I cap and plug this one.

 

[SuperG]

Aha! No wonder there are carbon deposits in the intake...Thanks!

 

[rangerj]

The crankcase vent hose is 14mm or 9/16, and can be replaced with "bulk" hose from any auto parts store.

It gets dried out and cracked, as well as full of deposits. The next tiime you have the intake off replace the hose.

It can be the source of a big vacuum leak and replacing it is a cheap preventive measure IMHO.

Carbon deposits are a fact of life for any engine that burns carbon chemical based fuel. thumb rangerj

 

[Slo-Sho]

What if one were to...leave "said" hose vented to the atomosphere?

 

[GreenBird]

Do not cap it and do not vent it.

If you cap it, pressure in the crankcase will build up, and it can eventually cause you to blow piston rings.

If you vent it, you need to vent both banks. Otherwise you will be letting metered air out, and sucking in unmetered air (not the same amounts). this will cause your a/f to become very fluky. You will have less power, and worse mileage. Venting will also send that carbon and gasses right into your engine bay (this is why you see K&N filters on some valve covers). However, no filter will clenze the air enough to keep it from stinking up the car.

IMHO, this mod is not worth it unless the car is a pure racer. The driveabilty benifits far outweigh the power benifits. Your better off cleaning your intake more often.

 

[Slo-Sho]

I have my fresh air inlet capped. I have the TB PCV hose rerouted to the ground and the inlet on the TB capped as well. I have never smelled anything while the car is stationary nor moving, EATC on or not. I'd rather not have to pull my intake and clean it every few months which is why I have followed others who have done this. Can you elaborate on "vent both banks" ? I thought the oil gallery wasn't isolated to only one cylinder bank?

 

[GreenBird]

what you describe as the air supply is on the opposite bank as the PCV, correct? If you vent one, you need to vent the other. If you vent one and cap the other, you'll experience what I said in my previous post. You should buy a small K&N breather cap to put on the "fresh air inlet".

Your routing the PCV to the ground probably helps, most people just put a k&n breather on it.

 

[SHOZ123]

The PCV system on the V6 only has one make up supply port, on the front valve cover. The system has common pressure on all parts of the crankcase. I very poor PCV system.

If you plug the make up port and leave the larger exhausting port connected, you will create a small vacuum in the crankcase during part throttle operation. This helps seal the rings, reduce blowby and also will help with the oil in the plug well problem on the V6 motor. At WOT the pressure becomes positive on all engines except those with high powered vacuum pumps on the crankcase.

 

[GreenBird]

SHOZ123:
If you plug the make up port and leave the larger exhausting port connected, you will create a small vacuum in the crankcase during part throttle operation. This helps seal the rings, reduce blowby and also will help with the oil in the plug well problem on the V6 motor. At WOT the pressure becomes positive on all engines except those with high powered vacuum pumps on the crankcase.

Thanks for the claification. That positive pressure in the crank case can prove quite deadly to most motors.