Correct! It's the vent or fresh air intake part of the PVC valve. The air that the PCV valve sucks out of the motor has to come in somewhere...
CK5
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Running Rich, Code 45, TBI 454 ***FIXED***
- Thread starter MTBLAZER89
- Start date
With the hose missing or broken you will have a vacuum leak.
Not on the vent (fresh air intake) you won't. You can only have a vacuum leak from the PCV vavle to the throttle body where it hooks up. There is no vacuum on the fresh air intake.
Not on the vent (fresh air intake) you won't. You can only have a vacuum leak from the PCV vavle to the throttle body where it hooks up. There is no vacuum on the fresh air intake.
The PCV valve creates a vacuum in the crankcase and if the "vent hose" is missing or broken you now have a vacuum leak.
The PCV valve does not create vacuum in the crankcase, it only ventilates. If you have a perfectly sealed motor and block off the fresh air tube you may get a small vacuum. Open up the fresh air tube and no vacuum.
This is turning into a pissing match. I will explain myself once again and hopefully this time you'll understand. An engine creates vacuum, of which the PCV valve uses this vacuum to evacuate any vapors from the crankcase. In order to do that there must be a vacuum in the crankcase (PCV valve) there must also be a "fresh air vent" so that the PCV valve doesn't try to suck out the oil. Once you remove either the PCV valve or the "fresh air vent" you now have a vacuum leak. If you don't believe me then with your engine running pull off your fresh air vent hose and listen to the engine change how it runs.
Scott is right. With that air hose broken the motor sputtered and missed ran really rich and popped the code 45. Fixing the hose fixed the problem with my truck.
It's not that I don't beleive you. Your just wrong. So I tried your theory of removing my fresh air vent. No change in the way the engine runs. Also installed a vacuum gauge, no vacuum. The PCV system does evacuate fumes from the engine but it is just air flow, no vacuum.
You also said you installed plugs and wires. So try it again, pull the fresh air vent off? if your motor runs differant I would look for a faulty PCV valve stuck open.
So then what would be the point of that hose? It goes into the intake side of the air cleaner. It would have to be pulling air out of the motor into the TB right from the Vacuum created by the engine? I don't know, but it seems to be part of a loop in the vacuum/PVC system on the engine and I imagine having it disconnected would do something.
It provides clean filtered air into the engine. PCV valve side sucks and the air should be clean going in. It could come in from anywhere after the air filter or you could have a seperate air filter or you could put a spacer on the TBI. If you have a lot of pressure oil or flow coming out of the fresh air vent it is showing blow-by from rings. How could there be a vacuum in this crankcase environment?
The PCV valve IS the vacuum source. Without a correctly working PCV system you will eventually start blowing oil out of every oil seal in the engine.
PCV is an emmision device emplemented in the 60's. It also has benificail results in engine longevity as well. It's not needed in an engine to run. Cars had vent tubes before that. Seals don't blow until there's so much blowby they fail.
If there is a vacuum in the engine as you describe, then the engine would also have a vacuum leak with the oil fill cap off or dipstick tube out.
I always read your posts and learn things from you, I'm trying to return the favor.
If there is a vacuum in the engine as you describe, then the engine would also have a vacuum leak with the oil fill cap off or dipstick tube out.
I always read your posts and learn things from you, I'm trying to return the favor.
PCV is an emmision device emplemented in the 60's. It also has benificail results in engine longevity as well. It's not needed in an engine to run. Cars had vent tubes before that. Seals don't blow until there's so much blowby they fail.
If there is a vacuum in the engine as you describe, then the engine would also have a vacuum leak with the oil fill cap off or dipstick tube out.
I always read your posts and learn things from you, I'm trying to return the favor.
You are exactly correct, remove the dipstick, oil cap, or "vent" hose and you have a vacuum leak.
Cars from the early 60's and earlier used what was called a road draft tube. This tube was installed somewhere in the engine (lifter valley usually) and then went down near the underside of the vehicle and as the car was driven the vacuum that was created by air passing over the tube drew the vapors out of the crankcase and into the atmosphere. With the advent of emissions testing the system became a closed system and rather than put the vapors into the atmosphere it drew it back into the engine and reburned it. A vehicle without a correctly working PCV system WILL start blowing oil out all of the seals once too much pressure is built up within the crankcase and it doesn't need to be a wore out engine with lots of blowby for this to happen.
I don't want to sound cocky as i may already have but this is something that i'm VERY knowledgable in and stand firm on my reasoning and explanation.
