Originally submitted by T:
- 1 Positive Crankcase Ventilation:
- 1.1 Description:
- 1.2 Grey Motor Crankcase Ventilation:
- 1.3 Early Red Motor Crankcase Ventilation:
- 1.4 Partial PCV:
- 1.5 Operation of the Partial System:
- 1.6 Fully Closed PCV:
- 1.7 Operation of the Fully Closed System:
- 1.8 EH Style PCV vs Later Fully Enclosed PCV:
- 1.9 PCV Valve Replacement:
- 1.10 Problems:
- 1.11 After Market PCV Valve:
- 1.12 PCV Valve Leaking:
- 1.13 Testing the PCV Valve:
- 1.14 Flat Type Oil Filler Cap:
- 1.15 Blocked Piston Ring Grooves:
- 1.16 Departure Gag:
- 1.17 Fitting PCV Connection to a Non-PCV Inlet Manifold:
- 1.18 X2 PCV:
- 2 Links:
- 3 Terms:
Positive Crankcase Ventilation:
Positive Crankcase Ventilation, or PCV, was fitted to Holdens from HK onwards. The Carburettor Idle Mixture has to be enrichened to allow for the fact that extra air is being drawn in. The PCV taps into the Inlet Manifold at the central most point to permit equal distribution of the PCV gases to all Cylinders and the best concentration of vacuum.
PCV is a system which causes fumes that are developed inside the Engine's crankcase to be drawn into the inlet manifold and burned.
PCV offers the advantages that these fumes do not escape to the environment directly to pollute the Environmant and they also perform a degree of Upper Cylinder Lubrication.
In any case the Crankcase needs to breathe. Under Full Throttle, Blow-By gases will be developed to a degree higher than the Intake Manifold can draw in. At Idle and moderate power settings the Intake Manifold will generate enough vacuum to draw in the Blow-By gases. There are 3 types of PCV System.
Grey Motor Crankcase Ventilation:
Grey Motors had no connection between the Crankcase and the Inlet Manifold so are not described as having Positive Crankcase Ventilation. Grey Motors did have a Crankcase Ventilation System. Air from the Fan was forced into the Oil Filler Cap and came out the Breather Pipe that pointed under the Car. This system was used for FX FJ FE FC FB EK EJ.
Early Red Motor Crankcase Ventilation:
This system is the same as that used on Grey Motors except there is no Fan forced airflow. The airflow under the Car draws air through the Crankcase. This system was used for EH HD HR.
This was fitted from HK on and uses the EH style filler cap. The rear of the rocker cover has the PCV Valve and a hose connected to the Inlet Manifold.
Operation of the Partial System:
On early Red Engines at idle or under partial Throttle, air is drawn into the Crankcase through the Air Filter style Oil Filler Cap at the front of the rocker cover.
Under full load and/or full Throttle excess blowby gas is generated. The excess blows back out of the Filter style Oil Filler Cap as well as into the Inlet Manifold provided there is sufficient Inlet Manifold vacuum to do so.
Fully Closed PCV:
This was fitted from HJ on and uses the flat style filler cap. The rear of the rocker cover also has the PCV Valve and a hose connected to the Inlet Manifold but there is a second pipe that connects between the Aircleaner and the front of the Rocker Cover.
Operation of the Fully Closed System:
On later Red and Blue/Black Engines, air is drawn into the Crankcase by a pipe connected between the front of the Rocker Cover and the main Airfilter when the Engine is Idling.
On EFI Black Engines, air is drawn into the Crankcase by a pipe connected between the rear of the Rocker Cover and the Airfilter when the Engine is Idling.
The Crankcase air is then drawn into the Inlet Manifold from the other end of the Rocker Cover through the PCV Valve.
When the Throttle is opened the airflow tends to flow into both the inlet manifold and the Aircleaner as a result of the combined crankcase gases and the force of the inlet manifold vacuum.
EH Style PCV vs Later Fully Enclosed PCV:
The original 149, 179, 161, 186 type Oil Filler cover was open to the air. These systems had no connection to the Inlet Manifold and the Crankcase vapours simply blew out into the atmosphere.
The later Partial System had a connection to the Inlet Manifold. When there was high vacuum in the Inlet Manifold, Air was pulled into the Oil Filler Air Filter, then into the Crankcase and from there into the Inlet Manifold.
The incoming air caused the Crankcase to be ventilated by drawing the Engine Fumes into the Inlet Manifold and burning them.
It also provides a degree of Upper Cylinder Lubricant and Inlet Valve lubricant, very desirable in these Unleaded times.
When there is limited vacuum present, Engine Fumes could escape from the EH style Oil Filler Cap, more so in a worn Engine and resulted in fumes getting into the cabin.
On the later model Engines, the Oil Filler Air Cleaner has been integrated into the Carburettor Air Cleaner to ensure that any escaping fumes are drawn into the top of the Carburettor instead of being allowed to escape to the air.
The Fully Enclosed System (the type that has been added to your 161)has the benefit of keeping the outside of the Engine cleaner as a result of keeping any escaping fumes inside the Engine.
Any PCV System forms part of the Inlet Manifold due to the fact that it's the Inlet Manifold that creates the vacuum to draw the fumes into itself.
Don't forget that any leak in the Tinware then forms part of the Inlet Manifold and if the car has an Air Leak in the Rocker Cover it will cause the car to have a lean mixture.
Once PVC has been fitted to a car it becomes your first step in troubleshooting gagging, lean mixture or flat spot on acceleration problems. You'll be wasting your time working other aspects of the Engine if you haven't satisfied yourself that the Tinware is a tight seal everywhere from the back of the Sump up.
A failed Front Oil Seal can contribute to the problem as well.
The pipe at the back of the Rocker Cover goes to the Inlet Manifold.
The pipe at the front of the Rocker Cover goes to the top of the Carburettor Air Cleaner.
The Oil Filler hole gets plugged off by the flat cap style Oil Filler Cap to ensure no air avoids being burnt.
"What reason or benifit would there be for having this setup"
The owner may have had an emissions conscience,
or if the Engine was old and producing noticable blowby it would have cleaned up the cabin so that he was no longer breathing CO and the like.
I can't recommend blocking anything or going back to the original 161 setup because ...
1. Blowby gases have to be allowed to escape. On early Holdens they flowed out a pipe that pointed to the ground. On EH's the pipe was called an umbrella handle because of its shape.
2. The Fully Enclosed System works very well and has the added benefit of providing more Upper Cylinder Lubricant than the open style system because all the gases are pulled through.
PCV Valve Replacement:
The PCV Valve is FuelMiser Part Number PCV-003. The PCV Valve Grommet is FuelMiser Part Number PCG-20.
When all the gaskets and grommets associated with the system are kept in good condition,
PCV can do a fine job of keeping the engine clean. It does this by placing an impressive vacuum on the crankcase, lifter cavity and the Rocker Cover.
The downside is that any air leak in the Crankcase appears as a leak in the inlet manifold. The symptoms of a PCV leak are exactly the same as if the Inlet Manifold had a large Carburettor leak, or any of the Diaphrams associated with the inlet manifold had a hole in them.
The most noticable symptom of a PCV airleak is a heavy flat spot on acceleration or "Kangarooing".
Oil Burning: After Market Rocker Covers:
After market Rocker covers - A word of warning
Submitted by Lovemyholden on Fri, 23/12/2005 - 02:32.
This might have been brought up before,
but I thought I'd mention my experience with these chrome "off the shelf" rocker covers you buy around the place.
Whether it's because you put on roller rockers or just like the look of the taller chrome covers, BEWARE! In my case I put on the Street Terra roller rockers, no worries there, but I purchased a generic after market rocker cover with 202 nicely stamped into the top of it.
Looks great, put it all together and all was happy. Or so I thought! Over several thousand K's I noticed my car started to ping under load. Strange, I checked timing, all ok! After a while it got so bad couldn't even do 100KPH without severe pinging. No alternative, take the head off and inspect combustion chambers. I found large sheets of thick carbon flaking off the pistons. I couldn't believe it. Motor is in good shape, good rings, guides etc, why is it burning so much oil.
I checked out the intake manifold and there was the answer, it had a thin coat of oil throughout it. What! where is this coming from? I traced it to the PCV feed into the manifold. What it comes down to is this. The stock Holden 6 rocker covers have a full length baffle with a breather slit either end. The Chinese (or wherever they are made by) Rocker Covers have a bent bit of steel folded over and a couple of tack welds holding it up under where the PCV grommet and hence the valve pushes into the rocker cover. It can suck not only crankcase vapours, but any oil that happens to be splashing about, straight into the PCV line and down the motor's throat.
Doesn't take long for this to cause the massive carbon problem. My solution was to rivet an aluminium baffle of my own in (not ideal as rivets leak) and secondly added an oil catch can inline with the PCV line (which did work well) you've just got to remember to empty it from time to time. I hope this saves people some problems, I learned the hard way. Check out the image of the piston.
This Valve, which is mounted in a grommet on top of the Rocker Cover, controls the flow of air through the Crankcase.
It allows air to flow out of the Crankcase and into the Inlet Manifold, but not back the other way.
The PCV Valve can wear out or become choked with deposits. In either case a rough idle will result.
If cleaning the valve out doesn't cure the problem then replace it. This Image shows the Fully Closed V8 Air Cleaner to Rocker Cover Connection
After Market PCV Valve:
Just a heads up re PCV valve. Had problems with a new re-co 186 donk chewing through oil big time- it was going up PCV pipe. I noticed the newer PCV valve seemed to be a tad longer than the original. If you push it right in, I think it actually sits right on the baffle plate in rocker cover, and constantly hoovers up oil. I pulled the PCV valve back a bit and secured it- it seems to be not using oil. I'll let ya know if it changes.
Cheers Rod Smith
PCV Valve Leaking:
A PCV Valve that does not seal off properly will cause noticable blue Oil Smoke on Startup. If the PCV Valve is carboned up it will allow the wrong airflow for the Throttle position. The reason is that airflow through the PCV Valve must be regulated because the pressure it sees is the opposite to the flow needs. There should be minimum airflow at Idle. This is when Inlet Manifold Vacuum is highest. There should be medium airflow at mid Throttle. This is when Inlet Manifold Vacuum is medium. There should be maximum airflow at full Throttle. This is when Inlet Manifold Vacuum is least.
Testing the PCV Valve:
Examine the PCV Valve for cleanliness and wash it clean in Petrol or spray it clean with Carburettor Cleaner if it's dirty. When it's working properly it will not allow Air to flow into the Plastic Pipe (Inlet Manifold end), but will allow air to flow out of the Plastic Pipe. If you push the Inner Valve with a small Screwdriver, it should spring back into place and seal tight. If the Spring is weak the PCV Valve will need to be replaced. The PCV Valve has to form a seal when it is in the closed position (downmost) and it must form a partial seal in the fully up position. There is an expanded explanation in the Link section in Myeh's Shed. This covers Partial PCV.
The repeated blowing of Tinplate Gaskets is a sign of excessive Blow-By gas being produced by the Engine.
The first step to curing this is to clean out the Piston Ring Grooves which may be completely choked with carbon. Blocked Piston Ring Grooves prevent the Compression Rings from being pressurised against the Cylinder Walls. Combustion gases should be directed behind the Compression Rings to make them seal properly. If the Piston Ring Grooves become blocked the Compression Rings lose their ability to keep the charge above them and excessive Blow-By gases result.
Flat Type Oil Filler Cap:
The rubber Seal under this Cap can go hard and cause a PCV Airleak. The symptom is a gag on takeoff. Replace the entire Cap and Seal together.
Airleaks in the PCV system will cause a rough idle and/or flat spots under acceleration due to excessive air being pulled into the Inlet Manifold. This rough idle can look very similar to the symptoms of a burned valve, but only appears once the motor is warm. Roughness goes away with more revs. A dry or shrunken PCV rubber grommet in the top of the rocker cover can also cause air leaks. You should be able to pull the PCV valve up out of the rubber with some resistance but no leverage. If it flops around then that's too loose. With the motor running you can put your thumb over the bottom of the PCV valve and feel suction.
Rocker Cover Spreaders:
These are long thin strips of metal that replace the original triangular washers under the Rocker Cover Bolts.
If the Engine produces excessive Blow-By, it's advisable to replace the original washers with the long thin springy type. The Rocker Cover Spreaders redistribute the pressure on the Rocker Cover Gasket evenly and prevent it from being cut around the Bolt Holes.
Rare Spares sell Rocker Cover Spreaders for Holden Engines.
Blocked PCV Connection at the Inlet Manifold:
DO you have any suction at pcv as sometimes where the pcv hose connects on the manifold gets blocked with carbon and there no suction so the pcv is not working ..
so check to make sure you have suction at the pcv.. wombat.
Blocked Piston Ring Grooves:
Clearing Piston Ring Grooves:
To clear the Piston Ring Grooves, steam is dirt cheap and very effective.
With the engine up to temperature, set the Engine to run at a fast idle and over a period of about an hour run the *mist* of 2 litres of tap water in mist form into the carby. Note this water is best presented in atomised form. You want the water to form into steam inside the combustion chambers and for the combustion charge to blast it between the piston and cylinders.
Once done, drive the car for a few kilometers to clear any Water from the inlet manifold once you've poured the water through.
An excessive amount of water may Hydraulic Lock the engine and bend a con-rod. Too much water and the engine will stall and need all the plugs removed with spinning on the starter to clear it out. You want to keep the Engine running and drawing mist until all the water has been used.
Restricting the Exhaust:
After the water treatment you might consider this method. It's cheaper than buying a new engine.
One trick I've used with success is to restrict the end of the tail pipe by 50%.
This causes the Piston Rings to be pressurised even when the Engine is running light loads and minimises the Blow-By.
If clearing the Piston Ring Grooves and restricting the tail pipe doesn't cure the Blow-By, then a Re-Bore/Re-Ring is the only cure.
One thing that can cause that problem in HZ's is a leak in the Tinware (Rocker Cover, Side Covers, Sump) ...
Make sure the Seal under the Oil Filler Cap is good because they can become hard, not seal properly and cause a delayed Air Leak. Consider investing in a new flat type Oil Filler Cap. Once the Air starts to move through the Rocker Cover the Cap is pulled down and seals. Before then excessive Air enters the Rocker Cover and finds its way into the Inlet Manifold causing the Gag. Tinware is easy to work and is a big part of the problem on Fully Closed PCV Systems. No amount of tweaking Carb or Ignition work will get around the problem.
Fitting PCV Connection to a Non-PCV Inlet Manifold:
This must be fitted as close the middle of the Inlet Manifold as possible to ensure that each Cylinder gets its fair share of the Crankcase Gases.
It's very easy. I have done it on the car with no swarf getting into the engine. You can just drill the manifold under the carby, tap the hole 3/8" BSP and fit a 3/8"BSP-3/8" hose brass tail. If you do have a go at it on the car make sure your drill bit is heavily coated in grease to catch the swarf. Remove and clean the drill bit regularly. The same goes for the tap. End of submission by meyeh.
there was a kit put out by dufor for this had every thing in it to do this i have seen them selling at swap meet for $20.00
new old stock has all the hose fittings ,hose pcv valve and instructions , if your in vic maybe check out the warragul swap meet i saw he will be there. you shouldent have to drill any holes should be a screw in plug on manifold you unscrew and screw fitting into. wombat..