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PCV help needed


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29 replies to this topic

#1 the sucker king

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Posted 31 January 2009 - 08:11 PM

please help me figure this out. I seemed to have pressure building up in the crankcase of the engine that I just replaced, and again with the new engine that I replaced it with. The PCV valve seems to be working fine.
The car has a weber on it and the PCV system is set up a little differently than stock. It was suggested that I need to set it up just as stock for it to work right, and I certainly am willing to change it, but I don't see why it's going to help in this situation.
I just read the FSM crankcase emission controll system page and I understand the system. I have the passenger side valve cover hooked up to the air cleaner. I have the drivers side valve cover running into the PCV. To make it same as stock, I SHOULD have a line running from the air cleaner to a T above the PCV. At part throttle the passenger side valve cover SHOULD be taking air INTO the engine. Instead it is spitting air OUT. The other side is also spitting air out as it should be. Passenger side is supposed to only spit air out at open throttle when there is more blow-by gas.
Both side putting air out indicates pressure, If it was all blow-by, I wouldn't think the car would run as good as it does. When driven at speed, the pressure is blowing oil out front and rear seals, which are both brand new.

As far as the missing hose from the air cleaner to drivers side hose, according to FSM, That is only to releave pressure so you won't suck oil into the PCV when you take a hard right turn, So I don't see how that would help this problem.

#2 GeneralDisorder

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Posted 31 January 2009 - 08:31 PM

How large are the hoses and have you cleaned the inside of the valve covers? I run 5/8" heater core hose hooked in just as you say but with the smaller line running to the air cleaner from the "F" shaped plastic elbow off the drivers side valve cover hose. All of mine have been hooked up this way for years and I've never had any issues. I would sugest that you make SURE the hoses are large enough and there are no restrictions in the valve covers or in any plastic connectors you are using for the hoses.

And use only OEM PCV valves too if you aren't already.

GD

#3 the sucker king

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Posted 31 January 2009 - 08:36 PM

Valve covers are clean, I will double check that the hose is not plugged. suppose it would be drivers side plugged if so. Hose is stock, I believe. Gonna go check it now.

#4 the sucker king

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Posted 31 January 2009 - 08:58 PM

Hoses are clear. With both hoses removed from valve covers, both valve covers are blowing air. Why would that be?

#5 DaveT

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Posted 31 January 2009 - 10:40 PM

With both hoses removed from valve covers, both valve covers are blowing air. Why would that be?


There is no seperation between the heads / rocker covers in the block. Any pressure under the pistons will freely vent from both covers.

If it's running good, not burning oil, getting the usual MPG, probably nothing wrong.

#6 bheinen74

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Posted 31 January 2009 - 10:54 PM

both sides are supposed to spit air out, that is why you need to make both lines go to a T, or an F

#7 SOOBOUTLAW

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Posted 31 January 2009 - 11:14 PM

There is no seperation between the heads / rocker covers in the block. Any pressure under the pistons will freely vent from both covers.

If it's running good, not burning oil, getting the usual MPG, probably nothing wrong.

Crankcase blowby buildup in normal running condition is common if you don't have a PVC system to draw a vacuum to remove crankcase pressure buildup caused by extreme temperatures and vaporizing hydrocarbons (and probably a few other things some Certified mechanics here can tell you(and correct me if I'm wrong)). Could be something else though. You ever top off your oil a little too much and turn sharp corner a bit fast? I've seen a cool smoke show from something like that.(In a Subaru, no less).
Hope this didn't get off topic. But, MAINTAIN YOUR PVC SYSTEM! It's there for a reason.

#8 DaveT

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Posted 31 January 2009 - 11:24 PM

I didn't mean to imply disableing or neglecting the PCV system. I was only addressing the idea of blow by with the hoses off being normal.

The smoke show during hard turns can be fixed by a Subaru modification kit. No more smoke shows for me.

#9 Loyale 2.7 Turbo

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Posted 31 January 2009 - 11:42 PM

...The smoke show during hard turns can be fixed by a Subaru modification kit. No more smoke shows for me.


I Didn`t hear about that Before... :eek: ...What is That? ... Could you Post Pics?

Let me tell you that if the Same Problem was in Previous Engine, and it came in the newly Swapped Engine, I Believe that the Source Could be in the Car, not in the Engine: a Clogged Exhaust.

I Suggest to Check if Exhaust has Restrictions...

Kind Regards.

#10 the sucker king

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Posted 31 January 2009 - 11:52 PM

There is no seperation between the heads / rocker covers in the block. Any pressure under the pistons will freely vent from both covers.

If it's running good, not burning oil, getting the usual MPG, probably nothing wrong.


both sides are supposed to spit air out, that is why you need to make both lines go to a T, or an F




It is not normal, and there is something to worry about as the pressure in the crankcase at speed is blowing oil out all over the place.


At partial throttle, air should be taken IN on the passenger side valve cover. Only at full throttle should it be going out. That's according to the factory service manual. So try again.

Let me tell you that if the Same Problem was in Previous Engine, and it came in the newly Swapped Engine, I Believe that the Source Could be in the Car, not in the Engine: a Clogged Exhaust.


Now your talkin'. I didn't think of that. the old intake and all bolt ons etc were swapped over from old engine. I was thinking that, and clogged exhaust was not on my mind. It is an exhaust that was done up front to back at a local shop. All just custom bent pipe. Would it be fair to say if the exhaust is too restrictive, I should be able to unbolt it at the heads, run the car and the engine should behave normally (as far as air flow from valve covers)?

#11 DaveT

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Posted 01 February 2009 - 12:22 AM

taken IN on the passenger side valve cover. Only at full throttle should it be going out. That's according to the factory service manual.


That's just wierd. Not trying to argue. The oil return passages from the rocker cover areas are large & irregular shaped. They go through the cam carriers, through the heads, through the block, into the oil pan. I have dissasembled these engines. There is nothing in them to direct airflow in any direction. With both hoses open, I can't imagine any reason the "air" wouldn't exit both aproximately even.

Could the description in the FSM be describing the flow under normal, original system (that is, before the mod that fixes the smoke show while turning) which had different size fittings & flow paths from the 2 sides in place?

#12 DaveT

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Posted 01 February 2009 - 12:27 AM

[SIZE=3][COLOR=yellow]I Didn`t hear about that Before... :eek: ...What is That? ... Could you Post Pics[I]?


I can take some tomorrow.

There might be a thread on here somewhere, I mentioned it once quite a while ago.

What it does is make both rocker cover vents the same size all the way back to the air intake. Original on non turbo SPFI had the passenger side 1/2" all the way, driver's side dropped down to maybe 1/4" part of the run up by the intake boot. The kit had a T and a cap and a hose or 2 to make all 1/2".

#13 ShawnW

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Posted 01 February 2009 - 12:46 AM

In this case we are talking about a Carb EA71 engine not an EA82 SPFI engine. I dont think theres that much difference in how the PCV system works on either engine but I thought that should be clarified.

#14 the sucker king

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Posted 01 February 2009 - 12:46 AM

Could the description in the FSM be describing the flow under normal, original system (that is, before the mod that fixes the smoke show while turning) which had different size fittings & flow paths from the 2 sides in place?



Yes that is true. it reflects what should happen with everything hooked up stock. I don't know about the mod you speak of, the breather from the air filter to the pcv side is supposed to eliminate oil into the manifold as mentioned in my first post.

Still, with the pcv side hooked up, both sides blow at idle. So it is not working right and the fact is, there is pressure inside the case. I am also familiar with these engines, I've torn down a few. Didn't meen to be snippy, I'm just trying to fix a problem.

I will explore the exhaust possibility tomorrow, and I'm wondering if that is the case, what roll did it play in the engine I blew up?

should have mentioned, this is an ea71.

#15 DaveT

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Posted 01 February 2009 - 01:23 AM

should have mentioned, this is an ea71.


I haven't touched one of those in about 20 years. But I did rebuild one back then. I don't remeber the PCV hose configuration.

#16 Loyale 2.7 Turbo

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Posted 01 February 2009 - 02:59 AM

... I should be able to unbolt it at the heads, run the car and the engine should behave normally (as far as air flow from valve covers)?


Well... I do preffer to unscrew & Drop the Exhaust Pipe right from the "Y" pipe, so you can check from there in two directions: First check the Flow from behind the "Y" to the Muffler`s out, then check the "Y" itself for bad done Cuttin` / Weldin` job (You said the Exhaust pipes aren`t Original, they`re a Shop work and maybe they made a Mistake there, one Head`s exhaust can be bad routed into the "Y" causing backpressure) and you can check the Flow from engine to the "Y" pipe...

I Don`t Suggest you to Start the Engine without the Head`s Out Pipes to the "Y" because if you let engine to Warm, the exhaust gas can get very Hot and Melt the Axles` Boots... unless you just try it for short time to measure the Engine`s Pressure... Be Careful; exhaust can get Very Hot...

I Hope this can Help, Good Luck!

Edited by Loyale 2.7 Turbo, 01 February 2009 - 03:02 AM.
bad written Word


#17 the sucker king

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Posted 01 February 2009 - 10:15 PM

Today I ran the car with the exhaust unbolted from the heads (it is a one pisce custom exhaust), and the same thing, blowing OUT both valve covers at idle and any other RPM.
So I rule out the exhaust being clogged or too restrictive. Here is the FSM page:


Posted Image

Can anyone with a good running stock ea71 or ea81 pop the hose off of their passenger side valve cover while the car is idling and report here if it is taking air in or out of the engine?
For that matter I would be interested with both valve cover hoses pulled, are they doing what they should.

I have dissasembled these engines. There is nothing in them to direct airflow in any direction. With both hoses open, I can't imagine any reason the "air" wouldn't exit both aproximately even.


I thought about this. Is it possible that the rotation of crank and cam direct the airflow from the right to the left side of the engine? I bet it is.









.............

#18 DaveT

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Posted 02 February 2009 - 12:22 AM

The picture helps (BTW, how do you get the full sized pic in the post?)

The only reason the air flows as the arrows show is that the engine manifold vacuum is lower pressure than the air at the air cleaner. It will only flow that direction when the manifold vacuum is stronger than at the air cleaner. If you remove the hose from the PCV valve side, air will come out normally. It will also come out the other side, wether it is connected to the air cleaner or not. If you remove the side opposite the PCV, air may come out, depending on the pressure differential. I never tested to see if the suction to the PCV was strong enough to remove all the blow by and make noticeable suction on the opposite port.

The pressure differential varies with engine RPM and throttle position. The relation of throttle position and engine RPM depends on the engine load.

I can't think of any way the pistons / valvetrain could effect air flow - the clearances are far to large for any of them to pump air from one side to the other. My experiences with test running engines in car & on stand have always been air exits both sides when the PCV hoses are disconnected.

The PCV valve has springs in it that allow it to be open or closed at particular pressure differentials & flow rates. I'm not sure if I have an old EA71 PCV valve to look at.

I remember a thread or 2 about adding an oil seperator to the PCV lines a while back.

#19 the sucker king

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Posted 02 February 2009 - 12:34 AM

To get the full page size, I just scanned it at 100%, uploaded it to photobucket and used the img tag.

I don't quite understand what you are saying, but the bottom line is I have abnormal pressure building up in the crankcase, and the air does not seem to be moving as this chart from the FSM says is should. I think the two are related.

If you are saying that it will only flow like this if everything is hooked up, at the very least I should be able to pop the air cleaner and put my thumb over the hole to the 1 & 3 side and it should be sucking, right? This I haven't
t done, but will.

Read the text over the picture as well, it will back up what I've been saying.

Edited by the sucker king, 02 February 2009 - 12:39 AM.


#20 the sucker king

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Posted 02 February 2009 - 12:43 AM

just occured to me, If Oil cap is not sealing air tight, Is that drawing in air That would otherwise be drawn into 1&3 valve cover? just a thought. Still, if that were the case, It would also aleveate pressure in the case. So frustrating, I want to huck the car in the river.

#21 GeneralDisorder

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Posted 02 February 2009 - 12:47 AM

You are correct - it will only flow when the system is hooked up. There must be pressure differential to create the flow. If you break the system by removing a hose it will not be flowing.

As to the pressure build-up, it doesn't take much at all. I caused a similar problem with an EA82 of mine when I installed a Weber and temporarily rubber-banded a red shop rag over the PCV hose as I didn't have a T readily availible. The drivers side cam seal popped out. The rag was not balled up - it was drawn tight across the hose opening and I could blow through it. But it was still too restrictive. Are you SURE you don't have any carbon build up inside the lines or connections? Just because you can blow through them doesn't mean their full inside diameter is clear. I've seen them plug up till only a 1/4" hole was left - this causes a ton of oil to be ingested down the intake and soak the air filter.

GD

#22 the sucker king

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Posted 02 February 2009 - 12:58 AM

Are you SURE you don't have any carbon build up inside the lines or connections? Just because you can blow through them doesn't mean their full inside diameter is clear. I've seen them plug up till only a 1/4" hole was left - this causes a ton of oil to be ingested down the intake and soak the air filter.

GD


No not 100% sure, but taking hose off of pvc valve, Valve is sucking and air is pushed out of hose prtty good. I have that stock F fitting on there, will clean it all out tomorrow. What else could this be. two engines now have had this problom with common manifold and exhaust. going crazy over this.

As far as testing the system intact, I should be able to pop the air cleaner and stick my finger over the fitting to the 1&3 hose in the air cleaner box, and it should be functioning, correct?

#23 DaveT

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Posted 02 February 2009 - 01:00 AM

just occured to me, If Oil cap is not sealing air tight, Is that drawing in air That would otherwise be drawn into 1&3 valve cover?


Yes, the oil filler is a larger path, so air could flow through it easier than the normal port on the cover.

But if the oil filler cap is off / not sealed, air will leak out, reducing the ability for pressure to build up in the crankcase.

Also, don't forget, the manual was translated from Japanese, and sometimes meanings get a little twisted in the process.

Check what GD mentioned.

I haven't had to do battle with excessive crankcase pressure, so I'm kind of limited to more general suggestions.

#24 the sucker king

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Posted 02 February 2009 - 02:27 AM

the scan from FSM that I posted was from 1980. I just checked a manual from 1978 and it shows air being pumped out of both valve covers, however there is no pcv valve on that diagram, both sides go to air cleaner.


Another possibility? If air injection valve is stuck open, could that be another source of air going into the crankcase? The air injection is routed into the exhaust ports of the heads, but could wide open valve be introducing more air than heads can pump out, and the excess ends up in the crankcase?

What about EGR valve, it is capped from weber conversion. Do I need to look into this? I have run other rigs this way with no consequence.

Could the carb itself be to blame? That is, is the weber pushing more than engine can handle? Do I need to look at jetting?

If some of these suggestions seem off the wall, I am just looking at where else there is air flowing into the engine.

Maybe it would help if I snapped a photo of the setup and posted it?

I suppose I still have lots of investigation to do, eventually with the help I am getting here, we will solve this.

On a brighter note, the frustration I am having with this car has gotton me to work in earnest on another car, work I have put off for far too long.

#25 Greenley

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Posted 02 February 2009 - 06:10 PM

Can anyone with a good running stock ea71 or ea81 pop the hose off of their passenger side valve cover while the car is idling and report here if it is taking air in or out of the engine?


I went ahead and checked both my EA81's.
One Weber'd with the same PCV hose routing as you,
and one Hitachi with the stock "F" configuration.

Both sides are pushing air out on either engine.

My $.02

Edited by Greenley, 02 February 2009 - 06:12 PM.





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