PCV valve problem?

Hey guys. I have a 69 Mustang Mach 1 with a 351W engine. I made a complete restauration of the car and the engine. After a while, the rear main seal started to leak and I start to notice oil coming out of the valve cover brather. The engine have a PCV valve on one valve cover and a breather cap on the other. I really tire to clean the engine so I want to resolve the problem. I`m using sinthetyc based oil. I need some ideas. How can I test the PCV valve? Thanks from Argentina  

with the engine running...  at idle speed...    you probably have one breather ...  take it out.... place your hand over the breather hole in the valve cover...    block it for 5 seconds...  pull your hand off..   you should he a little POP where you are breaking the seal and air rushes in...  

if you do not have vacuum build up , take the pcv out of the other cover...   place your finger over the end... see if there is vacuum there...     yes...   good... then unplug the pcv from the end of the hose...    with the engine at idle speed... when you unplug it... the engine should stall ...    if it does not...  you might have a restriction in the hose, in the fitting into the intake manifold..  i have found carbon buildup that reduced the amount of flow to almost nothing...

there is a weak spring inside the PCV valve...   when you shake the pcv... with it off the car .. you should hear it rattle inside..

i have also had the breathers clog up...     this blockage stops the air flow into and out of the motor...  so the pcv system can create vacuum in the pan... but under load... when the blow by exceeds the pcv flow... blowby is vented out the breather. if the breather is clogged... the blow by can build up and blow out out of seals and gaskets..



at idle... the pcv pulls crank case vapors into the intake...  the vacuum is high... the valve is pulled into the opening.. reducing flow...

under load.. the intake vacuum drops... the valve is pushed back slightly... letting more flow through ...   there is a lot more blow by under load...

at cruising speed... the intake manifold vacuum is high again... the valve is pulled into the opening.. reducing flow...

at no point in time.. does the pcv flow ever get blocked..

there is a slight problem... back in the mid 90s... the parts manufacturers and reboxers... consolidated part numbers... by shape...   not flow numbers... so the PCV valve might be too big.. or too small.... for you application...

too big... it will cause the motor to use oil at about 400 miles per quart...

too small... you will get out on the outside of the motor...


http://en.wikipedia.org/wiki/PCV_valve  

Thank you for your answer. One more question: What size of PCV valve should I use on my car? The one that I have on it is one of those billet ones and says 5.0 on the botton. Thanks again.  

i would think from your  description... that you might need more flow...  but i have not a clue to what you have in your hand... do you remember the manufacturer????

when you pull the breather.. with the engine idling... do you get the pop sort of sound when you pull your hand off ????? or do you have pressure ????



i don't remember if you said your motor was rebuilt...... if so.,. did you break in the rings with conventional motor oil in the pan...  or did you go synthetic from the first start....

have you done a compression test lately????   do you have a cylinder leak down tester.. and an air compressor to run it..  

Ok, I did run a compression test, everything seems to be fine. When I put my and on the breather hole I don´t feel a POP, is more like a small blow.
Yes, the engine was rebuild and I used mineral oil to do the brake in.
I did buy the PCV valve in JEGS, I don´t remember the brand.
You´re helping me very much, thank you.  

Question, how many miles are on the engine since it had a rebuild? If like 6,000 or less miles there could be a chance the rings never seated, especially if you switched to synthetic oil before then.  That will cause major blow-by.  
-
The Silver Buick- '77 Skylark coupe w/ a Fuel Injected Buick 455&TKO-600, '72 Centurion Conv't - 455w/TH400, '67 T-bird 4Dr (suicide) w/428&C6. Needing to replace a '69 Firebird 400.

http://www.bangshift.com/forum/index.php?topic=6189.0

The car has already 10000 miles but the problem started maybe at 5000. The engine was put together with moly rings, I think these kind of rings are a little bit harder. However, the compression seems to be ok (150+ PSI)  

I honestly don't know how unseated rings effect compression checks.  5,000 miles hmm.  
-
The Silver Buick- '77 Skylark coupe w/ a Fuel Injected Buick 455&TKO-600, '72 Centurion Conv't - 455w/TH400, '67 T-bird 4Dr (suicide) w/428&C6. Needing to replace a '69 Firebird 400.

http://www.bangshift.com/forum/index.php?topic=6189.0

Well, I don´t know either. I´m mechanic and my guessing is that if I had bad rings the compression should be low. I´m in Argentina so take the engine apart to see what´s going on is not that simple because the parts. I have a complete set of gaskets but I´m not sure about to find rings around here. The car runs beatifull it´s just a matter of cleaning oil every time that I take the car for a run. I guess if I get tired of cleaning I´m gonna have to do it once for all.
Back to the problem. What do you mean with hmm?  

ok... don't take the engine apart.....

pull the pcv out of the valve cover... see if there is suction on the end...

unplug the pcv... with the engine running..   the engine should stall...  if the hoses are hooked up right..

i went over to jegs....  did you buy the 20 buck jegs billet pcv ... if so.. did it come with additional washers, springs and internal parts...  if so you can change the flow rate by changing the internal parts..

says so right on the cover of the catalog... not on the individual web link...

JEGS 52225   billet PCV valve..  

Yeah I wouldn't pull the engine apart either unless I knew for sure what it was.  I would switch back to dino oil though, at least for another few thousand miles to see if the probably goes away. One of my Buick's leaks out the rear main with synthetic but doesn't leak a drop with dino oil.

What are the driving habits when the car is out? Is it a race car, WOT plenty of times, or just a cruiser? PCV's don't work at WOT and the Breather will leak oil if there isn't a good baffle in the valve cover.

Wayne, I don't get the diagnostic purpose of unplugging the PCV valve and seeing if the engine stalls?  If it stalls it means the idle is set proper, if it doesn't it means it's running rich. But in either case how does stalling the engine relate to crankcase ventilation?  
-
The Silver Buick- '77 Skylark coupe w/ a Fuel Injected Buick 455&TKO-600, '72 Centurion Conv't - 455w/TH400, '67 T-bird 4Dr (suicide) w/428&C6. Needing to replace a '69 Firebird 400.

http://www.bangshift.com/forum/index.php?topic=6189.0

what i want to know by unplugging it...   if the engine stalls when the PCV is unplugged from the end of the hose verifies that the hose and passage has enough flow and is not restricted...

my thoughts are if the pcv is not pulling enough air flow... something is wrong somewhere...   i have run into blocked hoses, flattened hoses... bent closed hoses, carbon build up in the threaded hose barb, carbon build up in the passages behind the threaded hose barb...




i even emailed jegs..

Thank you for your inquiry with Jegs High Performance. The billet PVC valve in our Jeg’s brand simply unscrews and in side is a regular style PVC valve that you can pick up at your local auto parts. If you have any more question don’t hesitate to ask either by email or give us a call ...


so perhaps he just needs a larger PCV valve installed into his billet body...

but.. he lives in a argentina ... it's not like he can drive to the autozone...  so  making sure the entire system works... will solve weeks of waiting..

i just try to cover all the bases as a professional mechanic...  sharing my 30 years of fixing the unfixable...  trouble shooting at repair shops... training their techs....

i have a question...   the autozone.com web site be accessed from argentina???  put in zip code 90026 when it asks for it.. so he can see various pictures of the different pcv valves after he gets it out of the housing..  

try copy and pasting this link...

http://contentinfo.autozone.com/znetcs/product-info/en/US/chl/PCV1115/image/8/

if i get a chance... i will stop by a parts store today... and have a look at several pcvs...  see if there is one with a larger than the 5.0 size...  the 1115 is for a 69 ,351W 4bbl...  

Ok, so that is assuming it's not running rich at idle (it'll idle up if it is when unplugged).  I've seen those issues with PVC systems as well, and assumed they would be clean of build up, though collapsed or a too tightly bent hose is possible.  Thanks.  
-
The Silver Buick- '77 Skylark coupe w/ a Fuel Injected Buick 455&TKO-600, '72 Centurion Conv't - 455w/TH400, '67 T-bird 4Dr (suicide) w/428&C6. Needing to replace a '69 Firebird 400.

http://www.bangshift.com/forum/index.php?topic=6189.0

I've seen rings that were installed upside down and have good compression test let to much oil into the cylinder. Also, when installing the rings did you use honing stones that were 320 or 400 Grit?  If you used a 220 or lower numbered grit stones it can wear off the moly surface damaging the moly top ring. The second ring are often just iron and don't get damaged as easily, so they can maintain somewhat good compression. But checking for restritions thoughout the PVC system like waynep7122 described is what I'd do first.  

well guys, I really aprecciate all your information. First, the PCV valve came with out any kind of parts, just the valve. The car was restored from the bone and I did the job so I know everything of the car. All the hoses are new, everything is clean and neat. I put the engine together with everything controlled by the machine shop and the guy over there was very  good and help me a lot when I need it.
I remember you that the car start with this problem after 5000 miles. The other day I did all the tests that you told me to do and I did not see nothing wrong. I drive the car aas cruiser, I do some hard acceleration from time to time but not so often, nothing crazy. I was thinking to switch to mineral oil back again. we´ll see. Thanks!!!