PCV modification sucked, but second attempt succeeded!

So as not to detract from Nib’s 342.5 thread, I thought I would start another one. This is a follow-up on changing the PCV plumbing on my car. Reading Nib’s thread gave me the idea.
Took the car out this morning and drove around thirty miles. Open road, easy 55 cruising. When I got home I decided to inspect the new scheme, and found a significant amount of oil in both air cleaner housings. There is so much suction going on that oil is being pulled from the timing chain housing, and goes to both air cleaners, through the intake manifold. On my car, at least, the connection to the timing chain area is a bad idea.
It seems to me that the OE PCV valve allows significant airflow through itself, which may explain why it succeeds in pulling oil vapor through the small housing on the back of “B” bank air cleaner.
I have put things back to where they were before, for now. I may experiment with different PCV valves, and see whether my idle speed changes, and I am curious to see whether Nib has good results from the ME Wagner PCV.

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That sucks indeed Dave…
What if you reverse things, i.e. suck through the original rubber boot thing with the original screen oil separator, and get air inside the engine through the chain tensioner plug?
I’m pretty sure that there is plenty of oil splashing around the tensioner plug that can get sucked in.

This is a very informative article I had found some time ago, might give you some inspiration.

PCV Breather Systems.pdf (1.1 MB)

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I’ve been thinking of different ways of adding a breather somewhere. The cover plate over the “vee” is a possibility, but I am not sure exactly where the distributor drive is positioned, and I really don’t want to tear things apart that much. Right now I have an expandable plug in the timing chain cover and it is difficult to add an elbow for a breather to that. I’ve ordered an OE plug and then I can probably add an elbow and some vertical tubing with a filtered (small) breather on top.
Then blank off the 7/16 hole in the back of “B” bank air cleaner. Still thinking!

This is a follow-up to my PCV adventure .A new OE rubber plug showed up today, and I drilled a hole through it so a 3/8 90degree elbow would be a tight fit.

I removed the new rubber plug in the timing chain cover, and inserted the new drilled OE plug, followed by the 90degree elbow. I used clear reinforced hose to make sure no oil was going where it was not supposed to go.

Another elbow up above and a short piece of tubing goes to a new 3/8 fuel filter, so no dirt gets into the crankcase.

The PCV plumbing pulls air from the back of “B” bank air cleaner, and the air flow is significant. I wanted the PCV air to flow through the crankcase, so I blanked off the hole in “B” bank air cleaner with a fridge magnet! (Adjustable. Removable. No damage.)

I left the cover off the air cleaner, and attached the air temp. sensor, then started the car.
The fast idle was the same as before, and so I completely covered the hole in the back of the air cleaner , and I could feel suction on my new plumbing. The engine warmed up, and settled down to it’s normal idle speed. The system works, and after a few drives I may change the clear tubing for something less obvious.

Do I understand correctly, it now sucks air in the engine through the chain tensioner plug and out through the big rubber boot at the top of the engine?

What happens at WOT?

Yes. PCV plumbing is unchanged, except for the fact that the 7/16 hole in the back of “B” bank air cleaner is covered. The full test drive will be in about an hour. I will find out what happens at WOT. I may make a rubber check-valve that is sucked shut , but will open with zero vacuum inside “B” air cleaner. All the cars I have owned with a similar PCV never had a problem with any pressure buildup at WOT. That’s the reason for the clear tubing- to see if any oil migrates in the “wrong” direction.

Aristides, Test drive completed. Just outside of town there is a straight stretch of road, several miles long. Open fields on each side, and no intersections .Outbound, I let the car cruise at 60MPH. I finally reached an intersection where I could turn around, and opened the hood. There was no sign of oil in the clear tubing.
Coming back, the car enjoyed an Italian Tune Up. Twice. On getting home I looked at the clear tubing again, and no trace of oil. There was gentle suction on the fuel filter port. Engine idle speed is unchanged from yesterday. I am happy with the results so far and will keep an eye on things for a while.


Final report, now the car has travelled a few hundred miles.
Modified PCV works beautifully. I took these photos ten minutes ago. The fridge magnet blocks the hole in the back of “B” bank air cleaner, and there is no sign of oil anywhere, including the throttle butterfly.

I shortened the metal tubing on the OE setup, and used clear braided tubing to connect to PCV valve. There is slight discoloration on the clear tubing from the oil mist passing through it.(Which means the system is working.) The air supply tubing, fed through a fuel filter, is like new.
I used the OE PCV valve, but a Fram PCV valve could be used instead, although there would be less airflow running through it, and a slower idle. The engine seems happy with the change!

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Hey Dave. I was wondering how you made out. And I just found out. The Wagner I installed on a client’s car had basically the same issue. But the Wagner allowed me to adjust idle and cruise vacuum be applied so oil in the intakes was reduced (not stopped).
I think if we digest the stock system and an improved (hopefully) system we can better understand.
Stock pcv:
Crank case ventilation (fresh air coming into crankcase) … none
Crank case vacuum. Stock pc valve isn’t really connected to crank case vent (rubber neck) it’s just in the area along with its mounting location behind the air filter. So, vacuum in this location is limited and dependent on pc valve spring tension and plunger weight.
So basically, this stock system relied on positive pressure in the crank case to push vapors out through the rubber neck into the area of the air filter.
When brandy new this system apparently kept the EPA and such happy. But as time wears on the rear main seal (leather and labyrinth) and half-moon seal and cam plug and… aren’t as tight as new. Here come the drips.
Know just a question/thought about conventional pc valves. This topic is discussed at the Wagner site. What spring tension, what plunger weight, what orifice size? How does anyone know what’s proper. And this system is not like the owns you might be used to where the pc valve is mounted in the cam cover and vacuum is directly applied.
So, this Wagner: Works on the same principle as a conventional pcv. But you have the ability to tune it to your specific application. You can/will run into what Dave and I have run into (oil being drawn into intakes). But that’s a function of where we put the suction of this system. I think on these two applications we are trying to keep it as simple and painless as possible. Doing such you will have hurdles.
Now with Dave’s new system he has removed the air filter access. So let’s just digest. This idea. Now the stock or not pc valve applies vacuum to the canister and the crank case ventilation system (which still has no clean air flow) so any air that is drawn into the crank case is from leaking areas. Cool stops leaks but, unfiltered air.
I think what we are trying to achieve is a slight consistent negative pressure in the crank case but with air flow to remove blow by gasses and any moisture.
I enjoy these under rated beautiful cars and the issues they have. And Love trying to make them more user friendly. Their day will come.
Looking forward to a long conversion cheers.

Dave I’m a little confused with the pics. I get the timing chain plug (I did the same) then it comes up to another 90 all good. Then it appears to go into a fuel type filter (for lack of better terms) but then I don’t see any after.

Wait a minute. Thats your fresh air?

I think if you could send us a diagram of the setup, we could all understand it better.
I like the idea and might do it too.

Yes. The fresh air is drawn into the crankcase through a new, clean, 3/8 fuel filter. The original plumbing of the PCV valve is unchanged, BUT the hole allowing airflow from the “B” air cleaner is blocked off, (fridge magnet) so the PCV tubing has to draw fumes through the metal tube and the oil separator.(and the crankcase)
Based on the idle speed staying the same as before anything was changed, I am happy with the airflow. If I want to reduce it I can use a generic Fram PCV valve (forget the number right now) but car runs great so I’ll leave well enough alone. After another coffee I may try to draw a rough diagram.)

I thought about a diagram, but as the computer and I barely tolerate each other a verbal explanation might be better.
On a 5.3 engine the PCV valve is plugged into a small chamber at the back of “B” air cleaner. That chamber has two more ports- one faces forward and is connected to a 90 degree metal tube that goes to a rubber cap, then oil separator, then crankcase. The other port is open to the back of “B” air cleaner.
When the engine is running, the PCV valve gets most of its air directly from “B” air cleaner. Any oil vapor from crankcase should be pulled into that airstream, and then into both intake manifolds.( Note “should”.)
If the port in the back of “B” air cleaner is blocked (fridge magnet) then there is a direct connection to just the crankcase, and the engine will attempt to remove air and fumes.
That is where the fresh air supply enters the picture, through the tensioner hole up front. Now the engine will succeed in removing vapor etc from the crankcase.
Remember that the engine crankcase is not totally sealed, and some air might be drawn in through the oil dipstick tube, which is a two-piece affair, like the auto trans dipstick.
That just about covers everything. Maybe the photos will make sense now.
If you want to change the PCV airflow you can use a Fram FV 181 or FV 202. One has an elbow, easily removable. Then adjust idle speed using AAV.
Hope that helps.

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Isn’t your air breather/filter just acting as an old fashioned system venting to atmosphere? What will this breather do during high positive crankcase pressure and little to no vacuum? As the engine ages, there is more and more blow by. So if you are flooring it at high speed/high rpm, wouldn’t that blow-by simply find it’s way out through this new air breather?

My first thought is that if the idle speed is unchanged, then the same amount of air is going through into the cylinders, so all you have achieved is perhaps change the path taken at vacuum levels seen at idle.

Next, I think it is misleading to talk about “airflow”. Air (and any airborne particles taken with it) simply moves from high pressure to low pressure and there is nothing else to consider.

Highest pressure is blowby gasses in the crankcase.
Next highest is atmospheric pressure outside the engine.
Next is the air pressure in the airbox.
Last, lowest (and most interesting) is manifold vacuum. This can be anywhere close to atmospheric pressure (at high loads, at hgh rpm wide open throttle and, finally, at low rpm and medium throttle) through low pressure (closed throttle, idle) to very low pressure (closed throttle and coasting downhill).

The pcv valve is interesting in that it controls where this oil will go. At idle, the vacuum will pull against the spring and evacuate the crankcase into the manifold. At medium throttle and low rpm, or at high load, manifold vacuum won’t overcome the spring, so the crankcase will be evacuated to the airbox. I don’t see that as a “bad result”.

What, if anything, you are being told if you see oil in the airbox, is that there may be more blowby gases than you’d like to think you had.

I think a diagram is going to help a lot to work out what is going on.

kind regards

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Before I became interested in Jaguars, I had (and worked on) quite a few v8 engines, mostly GM. A typical v8 engine has a PCV plugged in to one valve cover, and a fresh air supply, with a filter, located on the other valve cover. Sometimes the fresh air supply is hooked up to the air cleaner. All I have done to my engine is given the crankcase a “fresh air supply”. The OE pcv plumbing is unchanged, except for the open port to the “B” air cleaner is blocked with a magnet that can also act as a one-way valve, should blow-by become excessive. My engine has shown no evidence of excessive blow-by, and I have tested it! None of my gm engines were ever covered in oil, either. A few of them had high miles, too. Perhaps I should connect the “fresh air supply” to “A” bank air cleaner. That would be easy.
It is nice to see some interest being shown- Mr. K would be pleased.

You folks might have already seen this but interesting article.
Hemmings-Muscle-Machine-Jan-2016-p64-67.pdf (mewagner.com)

I am no expert when it comes to computers and “diagrams”. I thought the actual photos would be enough. I am not sure why using the word “airflow” would mislead anybody. Your first paragraph sums it up pretty well. I would like to hear some other ideas on making the PCV system function properly.

Just an addition. Before I started working on my pcv system I was wondering what kind of pressure was in my crankcase. I capped off the rubber neck and connected a vacuum / pressure gauge. Started the motor and the gauge indicated almost 2 psi at idle (motor has 20,000 miles). And yes, after the experiment was completed. The next morning, I was greeted with a substantial puddle of oil under the rear seal.