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View Full Version : 454 Mag MPFI PCV ???



fogducker III
08-18-2010, 01:54 PM
Just doing an oil and filter change on the 454 and thought I would check and/or change the PCV......last time out I had some oil seeping from the dip stick so I assume the valve was not doing it's job and releasing the crankcase pressure.......the PCV is not what I am use to, there does not appear to be a "check ball" in it....? There is also a line from the top of the valve routed under the side of the engine to a small brass fitting that is not hooked up to anything...?

Should I just clean and replace this fitting or get a different PCV and where does the end of this line hook up?

Yes I have a Merc factory manual but it does not show this...thanks for any direction.

mrfixxall
08-18-2010, 02:03 PM
the pcv on a boat dont have a check ball, the hose goes directly under the flame arrestor in front of the throttle body..If you look under it their should be a sptamped piece of alunumum witha hole in it and the hose just rests against the flame arrestor..as for the brass fitting thing?? mat be their for the moisture build upto drain ?

Tidbart
08-18-2010, 02:06 PM
Just doing an oil and filter change on the 454 and thought I would check and/or change the PCV......last time out I had some oil seeping from the dip stick so I assume the valve was not doing it's job and releasing the crankcase pressure.......the PCV is not what I am use to, there does not appear to be a "check ball" in it....? There is also a line from the top of the valve routed under the side of the engine to a small brass fitting that is not hooked up to anything...?

Should I just clean and replace this fitting or get a different PCV and where does the end of this line hook up?

Yes I have a Merc factory manual but it does not show this...thanks for any direction.

If I am not mistaken, that is just a ventilator. The other valve cover should have the pcv valve.

Don't know about the other end either. If I get a chance I will look at my motor, although, I don't remember that fitting from the rebuild.

B

CHACHI
08-18-2010, 02:41 PM
I have obviously missed a lot here....Jeremy what did you buy?

Ken

fogducker III
08-18-2010, 03:33 PM
Thanks boys....after a little research I found that Fix is right with the no check ball.....:bonk:

I will check the flame arrestor for a suitable fitting to hook the hose to and remove the "brass" fitting on the end of the hose. I will also check the other valve cover for a PCV.....

Chachi, sshhh! I ended up with a 1997 Wellcraft Scarab SCS.....short term only until I can find the right ZX.....:yes:

Dr. David Fleming
08-19-2010, 02:55 AM
You seem to be a little confused about what a PCV is and what it does. PCV means Positive Crankcase Ventilation - this is usually a plastic metal control valve located in one valve cover. It has a check ball and spring to shut it off at full throttle. It was invented in the 1960's as an anti smog device that allowed crankcase smoke and "blow-by" gasses to be sucked into the engine instead of blown out into the air. PCV is a way for fumes to get out of the crankcase - air goes into the crankcase on the other side of the engine on the other valve cover from a hose connected to the engine air cleaner or air intake - this is just the empty rubber hose you are talking about.

"Blow-by" gasses found in the crankcase are exhaust gasses that leak past the piston rings and exhaust valve guides - some hot rodders just pull all the PCV equipment off of the engine and hang a couple of vents on the valve covers. At full throttle the "blow by" smoke just blows out the top of the valve covers. These guys don't want the PCV smoke to screw up the carburetor or fuel injection mixture - they want nothing but gas and air going into the engine. The PCV valve is designed to feed into the bottom of the carburetor or fuel injection manifold - when the vacuum is high at idle the engine sucks the PCV valve open and vents the crankcase - at full throttle there is no vacuum or not as much and the "blow by" backs up goes out the other valve cover (one with no PCV valve) and is sucked into the air cleaner intake the other way by the empty hose.

The important thing is that it is not in your lungs - "Blow By" fumes are a high cancer risk and are known to cause cancer in laboratory test animals.

Also the more worn out your engine is, or the looser the pistons are, the more "blow by" gas becomes a problem - also a super charger on an engine generates high cylinder pressures and a lot of "blow by" - generally, a tight engine with good rings doesn't generate much "blow by" and the PCV valve is not much of an issue - generally no one really pays much attention to it.

CHACHI
08-19-2010, 07:13 AM
Thanks boys....after a little research I found that Fix is right with the no check ball.....:bonk:

I will check the flame arrestor for a suitable fitting to hook the hose to and remove the "brass" fitting on the end of the hose. I will also check the other valve cover for a PCV.....

Chachi, sshhh! I ended up with a 1997 Wellcraft Scarab SCS.....short term only until I can find the right ZX.....:yes:

thanks for getting me in the loop.

Nice boat by the way.

Just how big of a ZX you looking for? I can keep an eye out here for ya.

Ken

mrfixxall
08-19-2010, 09:41 AM
You seem to be a little confused about what a PCV is and what it does. PCV means Positive Crankcase Ventilation - this is usually a plastic metal control valve located in one valve cover. It has a check ball and spring to shut it off at full throttle. It was invented in the 1960's as an anti smog device that allowed crankcase smoke and "blow-by" gasses to be sucked into the engine instead of blown out into the air. PCV is a way for fumes to get out of the crankcase - air goes into the crankcase on the other side of the engine on the other valve cover from a hose connected to the engine air cleaner or air intake - this is just the empty rubber hose you are talking about.

"Blow-by" gasses found in the crankcase are exhaust gasses that leak past the piston rings and exhaust valve guides - some hot rodders just pull all the PCV equipment off of the engine and hang a couple of vents on the valve covers. At full throttle the "blow by" smoke just blows out the top of the valve covers. These guys don't want the PCV smoke to screw up the carburetor or fuel injection mixture - they want nothing but gas and air going into the engine. The PCV valve is designed to feed into the bottom of the carburetor or fuel injection manifold - when the vacuum is high at idle the engine sucks the PCV valve open and vents the crankcase - at full throttle there is no vacuum or not as much and the "blow by" backs up goes out the other valve cover (one with no PCV valve) and is sucked into the air cleaner intake the other way by the empty hose.

The important thing is that it is not in your lungs - "Blow By" fumes are a high cancer risk and are known to cause cancer in laboratory test animals.

Also the more worn out your engine is, or the looser the pistons are, the more "blow by" gas becomes a problem - also a super charger on an engine generates high cylinder pressures and a lot of "blow by" - generally, a tight engine with good rings doesn't generate much "blow by" and the PCV valve is not much of an issue - generally no one really pays much attention to it.



Here we go again, another fu(kin BOOK!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
For a simple ?????????????????????????

fogducker III
08-19-2010, 11:11 AM
LOL.......thanks all, I do realize what a PCV is and basically how it works, the issue was the set-up on the current motor is not what I am use to, hence the question and pics.......

After checking over the entire engine, there is no PCV on my engine, just the hose with the plastic "plug" that attaches to the grommet in the top of the valve cover under the air intake. Also, there is no place for attaching this hose on or near the air intake so this is why I think the hose was routed the way it was....I think I will just get a nice vent for the valve and remove the existing hose and be done with it.....the one issue is after running hard I got a slight "seeping" leak out of the dipstick area...???

PS. Ken, still doing my research on a ZX, but I sure do like the 22ZX that I saw on a local lake recently....:yes:

mrfixxall
08-19-2010, 11:20 AM
jeremy, check the valve cover bolts,they have a tendency of coming loose,,i have snugged them up a few time on my suburban (454) same valve covers..their a o-ring type seal and you can not over tighten them like the older valve covers..

use the pcv that merc supplyed,just make sure the hose goes under the flame arrestor and make sure the bottom side of the flame arrestor is clean or it may not work as well..between the oil on the bottom of it and all the junk in the air they do tend to plug up..

fogducker III
08-19-2010, 11:58 AM
jeremy, check the valve cover bolts,they have a tendency of coming loose,,i have snugged them up a few time on my suburban (454) same valve covers..their a o-ring type seal and you can not over tighten them like the older valve covers..

use the pcv that merc supplyed,just make sure the hose goes under the flame arrestor and make sure the bottom side of the flame arrestor is clean or it may not work as well..between the oil on the bottom of it and all the junk in the air they do tend to plug up..

Will do, very good points, I now think the "leak" tha was looking like from the dipstick area could well be the cover.....smarter then you look Fix.............:lookaroun::wink: