If you ever cut open a PCV valve
 

I don't know why all this weirdness always happens to me but I figured this might save someone some trouble.
I had someone work on the boat/engines and one of the things he said he routinely did was install pcv valves but he takes the check balls out. So he proceeds to buy 4 new valves, gut them and install them. Well before I actually stated the engines for the first time I had occasion to remove the valves and I see a round piece of metal laying on my rocker arm. Just complete luck that I happened to remove the valve and that it landed directly on a damn rocker and was visible. I had a hard time getting a good pic but there is an extra piece of metal (like a double thickness for reinforcement) up at the top of the valve that can fall out.

How the heck does it work without the check ball? Doesnt that defeat the purpouse?

I have no clue. Maybe to have it flow better? I trusted him and let him do his job. I mostly learned what not to do.

By the way. For those who followed the " what do these bearings tell you" thread, this was not the same person. This happened later in the game of take all my money.

Be thankful you caught the ball. Hard to say what the outcome would be if you hadn't. I've seen some things in the bottom of pans that baffle me to this day. Some that didn't take the path of least resistance that's for sure. I've never used pvc valves in marine however have seen them and from what I've heard is merc has gone back to using them. Probably more so to do with environment-issues than that of any real reason for them. But it's ok to spray hazardous chemtrails down on us everyday. Lol. Evidently your engine guy don't see the need for them however the only thing I would imagine he's doing by removing the ball is to utilize the pvc body as an oil trap. I'm not sure of what your running engine wise etc but regardless good catch.

Btw you may want to confirm he has the other three balls in his possession???

Good luck

without the check ball the valve is nothing more than a vacuum leak.did he say why he does this?

More like an oil siphon.

lets just call it a detonation monster!

They were gutted and empty. You wouldn't notice the extra layer of metal up inside unless you looked very closely. You can see in the pics how hard it is to tell which one is missing. The other valves still had this piece intact. It ended up being a non issue as the engines have been taken apart.I guess the pcvs were used because the engines had the provisions for them. As far as why the insides were removed, I have no idea. This was a reputable builder with an established business, not a side job. He just said that's the way he does it. The other end of the hoses was hooked up to the nipple on the flame arrestor.

That's how Merc does it on most of their motors. If you kept theirs, they are empty and nothing to gut.

Anytime you see a factory motor with tubes going to the arrestor, the PCV looking things are not actually PCV valves, because they are hollow inside with no springs/balls.

Issue is when people think these are supposed to be PCV valves,

PCV valves are not open to atmosphere, they are connected to full intake vacuum.

Very common for people to get confused on these, until they have been there and done that.

aahh,hoses hooked to flame arrester,totally different than to a vacuum source.

Basic na build. Here's a pic as he installed them. I actually thought this was common practice when he told me about it. I figured for sure others would be doing this and that's why I wanted to point it out.

Does the hose from the gutted PCV go to the flame arrestor or to the carb base?

See #10
http://www.mercruiserparts.com/Show_...FLAME+ARRESTOR

It's an internally open fitting that could be mistaken as a PCV valve
http://www.mercruiserparts.com/images/COMMON/47514.png

You guy are quick. I see you figured it all out while I was finding the pic to post. I wasn't aware hooking them up to the arrestor was much different other than it would be a weaker source of vacuum. These weren't hollow initially, they were full functioning pcvs that had the bottom removed and the insides taken out. Anyway, be aware of this extra piece pressed into the top if you ever gut a standard pcv valve.

See #9 and #10 post

bck - always good to post this stuff because you never know who knows what or not.

I'm glad for you that you found that piece on the rocker arm . Lucky !

Some merc apps use both one breather valve and one PCV valve for OEM stock apps.

http://www.mercruiserparts.com/Show_...d+Rocker+Cover

The guy who is making & using a knocked out internal PVC valve instead of using a real breather valve really is clueless. Why because the hole opening is 3 times bigger in size for the breather valve compared to a PVC valve. Crankcase pressure needs enough sizing to escape / vent.

In the link above post # 18 the breather valve is part # 6 or the same exact type is in SB parts diagram post part # 10 - you can buy them all day long from merc for real cheap. Cost 3.80 full retail and do not have to punch anything out of them.

Putting a PCV valve in the valve cover and attaching a hose to the flame arrestor is not going to do anything. A PCV valve needs a vacuum source, either from the base of the carb,, manifold like some of the HP 500's. Those fittings look like PCV's in post #18 but are not. They are plastic fittings allowing free flow crankcase ventilation to the flame arrestor. When your engine is idling or at low rpm's the vacuum in the manifold is at its highest which causes the pcv to open. Being in the open position it is now sucking unburned fumes, moisture etc out of the crankcase dumping it back into the intake to be re-burned. The machine shop that flowed my carbs told me NEVER install a PCV valve in high performance engine unless you want to blow it up. As someone previously said ...A Detonation Monster

^^^^ I am not trying to sound like azz here but ^^^^ I will bet you any amount of money in post # 18 part number 8 is a real working PCV in a Mercruiser stock set up app. I am giving out 2 to 1 odds any takers

http://www.ebay.com/itm/Mercruiser-N...-/200960287676

up to 3 to 1 odds

http://www.cpperformance.com/p-50660...8m2017060.aspx

No bet. Merc calls the plastic open fitting on the VC (that some mistake as a PCV) as a breather.

The one you are pinpointing is a PCV, which Merce refers to as a PCV.

The pic to your link shows #8 as a PCV (#8M2017060 VALVE, PCV $8.78), and #6 as a breather.(#97850T ELBOW, 90 Degree, Breather $3.71)

Anyway, as mentioned by others in the thread, a PCV will be hooked to vacuum, and a Crank Breather will be open to atmosphere, usually vented to flame arrestor.

Sure I agree - I never said the PVC valve is connected to flame arrester, Said some apps incorp both set ups inwhich can be common for Merc production stock apps. Just saying.

What I did basically mentioned is , have no idea why someone would spend all that time making a PCV into a breather valve when you can buy the breather valve in a 90 or straight app for a couple bucks.

Anyways was just showing that for whomever for info.

That’s just it Bup, you won’t find one at the local auto store and would have had to be ordered. I’ve been known to modify a few parts to make work. Like when I had a set of valve covers that had the oil fills open on both covers instead of an oil fill in one and the smaller hole in the other for a pcv. Had to use a chrome oil fill breather looking thing with a built in PCV valve inside. Then gutted the guts of the valve out and I was back in business. But that was a long time ago when I was a kid and had no money and a cool set of valve covers.
I have to say, even though we have been through this fight before on OSO, for about the last 30 years I’ve use PCV valves hooked up to the base of the carb on all my boat motors. Even my hydroplane that motor is completely open. It’s just cleaner.

Yeah, I'd have to say availability was why the would've been used. Merc would've required calling, waiting a few days etc. These you can get on any corner, any time.

Look at it this way:
IF the mechanics labor rate is say $100/ hr, it's going to take him $20 in labor (IF he can do all 4 PCV's in 12 minutes or less) to cut open an $8 PCV (x4). That means he's invested roughly $52 of YOUR dollars into modifying what could have been purchased for about $16 from OEM / Merc... Better in many ways to use the factory prescribed parts in this scenario.

I actually didn't notice if I was charged labor for customizing pcv valves. There was plenty of other bs labor charged though. Clearancing my old throttle brackets for more than what new ones cost. This wasn't really started as a beware thread though. I just wanted to warn people about the extra piece of metal if anyone ever does this. Based on him saying he commonly does this, I'm pretty sure there are other engines out there with this piece ready to drop into the valve cover.

Stupid quistion...what causes the detonation : the poorly vented valve cover or the crap vented into the carb via the hose to the air cleaner? Reason I ask? I just modified my valve covers. Had Edlebroc "tower" breathers blowing fumes into bilge/boat. Wanted to scavenge that crap and have it expelled out through the exhaust. Am I going to blow up?

Surprising how many people think PCV stands for Pollution Control Valve. :)

Interesting Wiki page on it. https://en.wikipedia.org/wiki/Crankc...ilation_system
That little stupid $3.50 valve cut vehicle smog emissions by half. At that rate for another $7.00 the only thing that should come out of the tail pipes is cotton candy and warm oxygen.

PS if it take your guy and hour to take apart 2 PCV valves you may need a faster mechanic.

So what exactly is the purpose of the PCV valves on the newer HP 500 intakes? I'm running that set-up on my HP 450 clones and I never understood why they added these.

because the epa is mandating it.the free ride for marine engines is over,most now come with cats.i think all under 500 hp are required to have cats.it,s a proven fact that a pcv system lowers emissions.

And in 2 years you will need 2 scan tools for these emission control MARINE engines. You will need a OBD II scan tool plus the lastest greatest Diacom or CDS. Year models 2018 starts the EPA / OEM marine standardization and then for the outboards when they get CATS. Huge changes are coming soon.

So those are there for emissions? Interesting! I know my buddy's new Master Craft X55 has the 7.4 Ilmor,which has 540 hp and his engine has cats. I won't be buying a new boat anytime soon, so i guess all I need to worry about are my two PCV valves.

Ya I guess my stuff will be grandfathered in being its as old as a grandfather. High tech in my world is an electric choke.

Yes, PCV's are for emissions, however, they also help greatly with getting humidity out of the oil.

or in simpler terms,,condensation in engine gets removed.less milky oil.

Yes, better wording. I'm currently in distress. I am being fitted into a straight jacket right now. :readinghelp:

So what exactly is the difference between running real pcvs to the intake and just hoses to the flame arrestor? I can see how pcvs have a strong vacuum actually sucking fumes out of the engine. What do the flame arrestor ones do? Just suck in what the engines push out? Doesn't seem like there's much sense to them.