In my 2002 Ford Focus, under the big air hose, above the egr valve, there is a hose about 1 inch in diameter that goes out the side of the top of the engine and down into the side of something that's either the lower part of the air filter box or something under the air filter box.
What is that hose?
Sounds like a crankcase vent intake hose.
"Steve W." wrote in news:f2hkjh$n98$ snipped-for-privacy@aioe.org:
Why does it need a hose for that, instead of just an air hole?
To prevent dirt from being sucked into your engine making it die an untimely death it sucks clean air through the air filter....
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06Mike Romain wrote in news:464c62d9$0$6399 $ snipped-for-privacy@unlimited.newshosting.com:
Then why does it have a separate hose instead of just a short pipe from the engine's filtered air intake?
Not that I'm trying to nitpick or anything. Just wondering how it works and why it's done that way.
Also why does the crankcase need ventilation?
The hose needs to be in the outer part of the air filter box so it isn't exposed to a vacuum because it is the 'intake'. The tube on top of the throttle intake has 'ported' vacuum showing in it.
Lots even have a second small air filter in the box for them so they are really away from vacuum, mine does.
These also have a PCV or CCV valve that sucks air from the other end or side of the valve cover into the manifold to be reburned. This keeps fresh air in the crank which prevents condensation and then sludge buildup.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06Mike Romain wrote in news:464caf8c$0$3982$ snipped-for-privacy@unlimited.newshosting.com:
You mean the air goes from the air filter box through the hose to the crankcase then through the crankcase and then out of the crankcase to the PCV or CCV? And the suction of the PCV or CCV is what sucks the air from the air filter box into the crankcase?
Yup.
Mike
Mike Romain wrote in news:464cb5fe$0$5699$ snipped-for-privacy@unlimited.newshosting.com:
Ok, that's clear now.
If the hose gets accidentally disconnected from the air filter box, is the risk of dirt in the crankcase the only consequence? Or do some air filter boxes somehow rely on the sucking from that hose, for proper operation? Such as some kind of balance between the vacuum caused by that sucking and the vacuum caused by the engine air intake sucking?
The reason I ask what seems like such a silly question is that the hose actually came disconnected somehow, and I noticed a slight degrading in engine performance, which improved after the hose was reconnected. But it was probably just a coincidence, because it wasn't enough difference to really mean anything, just random variations.
Yes, lots of newer engines are touchy for crank pressure. Some will miss bad even.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.