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Front valvecover hole by Johan
Started on: 02-08-2014 03:38 AM
Replies: 18 (587 views)
Last post by: Patrick on 02-11-2014 05:47 PM
Johan
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Report this Post02-08-2014 03:38 AM Click Here to See the Profile for JohanSend a Private Message to JohanEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hi

I'm doing a engine swap, duke to v6. My v6 engine is missing the tube, (part of the recall kit) that fits the hole in the front valve over. I'm wondering if its possible to use a breather in that hole or could that lead to oil dropping on the cat?

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maybenot
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Report this Post02-08-2014 06:58 AM Click Here to See the Profile for maybenotClick Here to Email maybenotSend a Private Message to maybenotEdit/Delete MessageReply w/QuoteDirect Link to This Post
hi,
the front(closest to rear window connects to a port on the flex air tube from air filter housing. the rear(trunk side) connects under theplenum. i have read(and blindly follow) that they serve a purpose and should remain as designed. they also do not hurt or cause a loss of performance.
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fierofool
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Report this Post02-08-2014 08:04 AM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageClick Here to Email fierofoolSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
Others have voiced their opinions that it could allow oil to get onto the manifold or cat, if equipped. Being on the back side, it's out of sight and may become out of mind. It's also difficult to access. If you have the correct air intake, try making a request in The Mall for the needed metl tube.
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Johan
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Report this Post02-09-2014 02:54 PM Click Here to See the Profile for JohanSend a Private Message to JohanEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks guys

My plan isn't to block or remove the function, just though I could put a air filter/ breather in that hole instead of taking the air from the normal air filter via the tube.

Johan
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Gall757
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Report this Post02-09-2014 03:08 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
I think you have the air going the wrong way in your head.....
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Patrick
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Report this Post02-09-2014 03:51 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Gall757:

I think you have the air going the wrong way in your head...


Come on now, Swedish people breathe the same way as the rest of us do.

Johan, I understand what you're suggesting. Sure, you could simply put a breather in the forward valve cover... but why not either get the proper tube, or better yet (if it's difficult to find one), just fabricate a tube to go from the forward valve cover to the rubber snorkle? That way you won't have to worry about the possibliity of oil (from crankcase vapours) dripping down on the cat from a breather mounted on the forward valve cover.
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lateFormula
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Report this Post02-09-2014 04:33 PM Click Here to See the Profile for lateFormulaSend a Private Message to lateFormulaEdit/Delete MessageReply w/QuoteDirect Link to This Post
Simple answer to Johan is yes you can put a breather in the front valve cover. But if you do this, you should put a plug in the nipple on the inlet tube so that you don't have a continuous sucking sound from the inlet tube. I have had a small K&N filter that has a metal cap and neck in the front valve cover on my car for over 20 years now. Works just fine.
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Gall757
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Report this Post02-09-2014 05:53 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:
Come on now, Swedish people breathe the same way as the rest of us do.


They all inhale when we exhale......that's why the world goes around....

but seriously, folks...........oily air is sent out of the valve cover and sucked into the throttle body via the air filter housing......so if you just put a filter on the valve cover, it will eventually get soaked with oil and probably stop working.

[This message has been edited by Gall757 (edited 02-09-2014).]

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Patrick
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Report this Post02-09-2014 06:07 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Gall757:

but seriously, folks...........oily air is sent out of the valve cover and sucked into the throttle body via the air filter housing......so if you just put a filter on the valve cover, it will eventually get soaked with oil and probably stop working.


Well, the flow of air is not supposed to be going in that direction on a healthy engine.

I prefer the stock breather system myself.
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Blacktree
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Report this Post02-09-2014 06:48 PM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageClick Here to Email BlacktreeSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post
Yeah, the air is sucked into that valve cover, not out of it. Plus, the Fiero valve cover has baffles around that opening, to keep oil from splashing out. Your engine would need to have REALLY bad cylinder blow-by, and/or a plugged up PCV system, to make oil blow out the breather tube.

I ran a breather filter on my old 2.8 V6 for several years, and it never leaked any oil onto the valve cover. That same breather setup is now on my 3.4 V6... same deal, no oil leaking out. That said, I did reverse the PCV system (so the breather is on the trunk side, and the PCV valve on the firewall side), because I was concerned about rainwater soaking the breather filter.
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Gall757
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Report this Post02-09-2014 09:27 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
OK, I had the air going the wrong way in my head.... .

perhaps the oil that I have seen in that tube is only from very sick engines.
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Report this Post02-10-2014 10:37 PM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageClick Here to Email BlacktreeSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post
On a high mileage engine, anything is possible. The rings and/or cylinders could be worn. The PCV system could be gunked up. And so on. Also, if the valve covers aren't baffled, some of the oil splashing around in there could get in the breather filter.

Boosted engines can also push some oil out the breather, during boost. The boost pushes the PCV valve closed. Plus, the higher cylinder pressure increases blow-by.

Also, even a perfectly good engine can suck in some oil through the PCV valve. That's caused by crankshaft windage. Some of that oil mist floating around in the crankcase gets sucked into the PCV system.
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fierofool
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Report this Post02-10-2014 11:02 PM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageClick Here to Email fierofoolSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
On one valve cover you have a tube that sucks crankcase vapors to the intake to be reburned. There is strong vacuum at the front of the throttle body, so there's no way air can travel into that tube to the front valve cover. On the other valve cover you have a PCV valve that sucks crankcase vapors to be pulled into the intake manifold for reburn. If air were being pulled in, then the PCV would probably never get plugged up with oil and sludge.

Even on a new engine there is a small amount of blow-by. Since the two valve covers are indirectly connected through the oil return holes to the crankcase, how can you have air going in one valve cover and out the other? There are baffles in each valve cover for the purpose of reducing the amount of oil droplets going out of the engine. They work in principal like the Fiero's water separator in the cold air intake. Remove either the tube or the PCV and you will feel puffs of air coming out, not a vacuum going in.
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Blacktree
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Report this Post02-11-2014 02:34 PM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageClick Here to Email BlacktreeSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fierofool:

On one valve cover you have a tube that sucks crankcase vapors to the intake to be reburned. There is strong vacuum at the front of the throttle body, so there's no way air can travel into that tube to the front valve cover.

There is manifold vacuum behind the throttle plate, and atmospheric pressure in front of it. The PCV system pulls air from the intake pipe, in front of the throttle body. So the PCV system is not fighting against manifold vacuum. It's actually being driven by manifold vacuum. As long as the manifold vacuum pulls out more air than the cylinders dump in via blow-by, the result is air being pulled in the breather tube. But once the blow-by surpasses the amount being pulled out via manifold vacuum, the net effect is air being pushed out the breather tube.

On a properly working engine in good condition, the airflow thru the PCV system resembles the diagram below.



The diagram isn't specific to the Fiero, but the general principle is the same.

[This message has been edited by Blacktree (edited 02-11-2014).]

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Patrick
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Report this Post02-11-2014 03:06 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fierofool:

...how can you have air going in one valve cover and out the other?


Because that's exactly how it's been designed to work!

Fierofool, it's back to Positive Crankcase Ventilation 101 for you.
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fierofool
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Report this Post02-11-2014 04:15 PM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageClick Here to Email fierofoolSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:

Because that's exactly how it's been designed to work!

Fierofool, it's back to Positive Crankcase Ventilation 101 for you.


I was thinking that since there's a vacuum all the way through the intake system, including the filter and snorkle, that it would be strong enough, given the large size of the throttle body, that it would also pull air from the metal tube attached to the front valve cover.

I just learned something. Did I graduate?
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Patrick
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Report this Post02-11-2014 04:33 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fierofool:

I was thinking that since there's a vacuum all the way through the intake system, including the filter and snorkle, that it would be strong enough, given the large size of the throttle body, that it would also pull air from the metal tube attached to the front valve cover.


Oh sure, there's a slight vacuum at the port on the snorkle... but it's a whole lot less than the vacuum at the PCV valve.

 
quote
Originally posted by fierofool:

I just learned something. Did I graduate?


A very nice diploma will be coming your way... after a small, very reasonable fee is paid to my account via PayPal.
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fierofool
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Report this Post02-11-2014 05:43 PM Click Here to See the Profile for fierofoolClick Here to visit fierofool's HomePageClick Here to Email fierofoolSend a Private Message to fierofoolEdit/Delete MessageReply w/QuoteDirect Link to This Post
I will be PM-ing my full name and address. You will have to pay cross-border duties and absorb the exchange rate of the US currency.
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Patrick
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Report this Post02-11-2014 05:47 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post

Well, forget it then.
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