PCV & Oil Consumption Valve Cover (1 Viewer)

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landtoy80

landtoy80

Joined
Mar 13, 2003
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North Front Range, CO
PCV Hose #2 & Oil Consumption, Valve Cover

When I removed the PCV hose, the one without the PCV valve (there are 2 PCV hoses on the valve cover) I see that it is sucking oil from the valve cover.
I know this is common on a high mi motor but why does this happen, what is going on under the valve cover to?
Is it liquid oil that is getting splashed up onto the baffle or is it oil vapor that is getting sucked up there? If its oil vapor, is that from blowby from the motor and is it from the valves or pistions?
Does the oil being sucked into the throttle body have any affect on the throttle body system?
If so, could I put a oil/water seperator on the hoses to keep oil out of the throttle?

What is in the baffle that is on the underside of the valve cover and what does it do?
When I had the valve cover off, I had baked on oil crud buildup in the baffle. I took a rubber hammer and pounded as much of the crud out of the baffle. Was I wrong in pounding out the crud, did I damage the baffle?
 
Last edited:
*Edit, hose names changed to proper names,

The # 2 PCV hose should not have oil in it, it takes air from the ambient pressure side of the intake as a clean air vent to replace air that the # 1 PCV hose is taking from the motor (the one with the PCV valve) the # 1 PCV hose is ported to the low pressure side of the throttle body

Or put another way clean air goes from the intake to the motor in the #2 PCV hose and air/ oil vapor /blow by gasses pas through the PCV valve and into the intake via No. 1 PCV hose

Is your PCV valve or line clogged? If the # 1 PCV hose cannot breath, pressure from blow by gasses carrying oil vapor would travel up the No. 2 PCV hose as it is the only remaining exit

When I pulled my # 1 PCV hose there was a considerable amount of oil in the line. I am going to put a pcv catch pan on this line

$20 pcv catch pan

More reading

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=24;t=000936


Sorry don’t know what is in that baffle, I thought somebody said it was screwed in place but mine was glued and I did not want to disturb it, I assume it is just a chamber where oil droplets can settle out and gasses can pass on but I don’t know for sure

Mine had some decent deposits near #6 and in front of the timing chain where there is little oil flow to keep them clean
ValveCover.jpg
 
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When you say you second pcv line, is that the one with the pcv valve or the one without?
When I removed the PCV hose without the PCV valve (with the motor running) the motor runs rough. There is a vacuum on that hose too.
My thinking was that the hose with the pcv valve was the suction side and the hose without the valve was the breahter side (letting in fresh air)but on my motor thats not happining (at least at idle).
THere is enough vacuum (suction) on the line without the pcv valve that it can suck the cup of SeaFoam (liquid motor cleaner) into the throttle.
 
The one I am (was) calling second is the one with the PCV valve , I am sure they have a proper name I just don’t know it

*Edit, hose names changed to proper names:


There should not be much vacuum at PCV hose #2 port on the intake just whatever restriction is cause by the air filter with should not be much at idle, just pulled my #2 hose and there is no oil in the line, I replaced that line a few months ago as the original was cracked, also did a little test, I put a thumb over the valve cover port and left it there for 30 seconds when I removed my thumb air rushed in to the valve cover shows that the #1 hose is working and keeping up with and overcoming blow by at idle

Maybe you could try that? If you are not getting vacuum in the engine when the #2 port in the valve cover is plugged you may have a problem


When I pulled the #1 hose it does not stumble, have some ideas why the difference but not sure, how old is you air filter? Also my truck was just run an hour ago might be in closed loop wile your may be in open loop if it was stone cold?
 
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I have the TRD filter.
The motor was cold when I pulled #1 hose.
#2 hose works fine as does the pcv valve.
I will try it with a warm motor.
 
*Edit, hose names changed to proper names,


do you get vaccume on the valve cover port for the #2 hose?
 
Last edited:
Man,


That's a great long valve cover..........:D


Could you imagine this engine as a NINE liter V12?


Prolly 400 horse and 500 lb-ft torque....:D
 
cruiserdan said:
Man,
Could you imagine this engine as a NINE liter V12?
Click to expand...


:eek: :bounce:
 
In the FSM;
#1 PCV hose is the one with the PCV valve.
#2 PCV hose is the one without the PCV valve, it goes to the throttle body.

With the motor hot and cold:
I have vacuum at #1 and #2 PCV hoses.
The motor will stumble and almost die with #1 and or #2 hose disconnected.
I block the valve cover port to #2 PCV hose and I have vacuum. This means I have vacuum from the PCV #1. The PCV valve is working fine.

As I posted in https://forum.ih8mud.com/showthread.php?t=24079 port 'R' is restricked and I have no vacuum at that port. I don't know if this is related.

I also have a slight delay when I snap rev the motor. I have posted it before but sounds like its not a problem but:
When I snap the throttle from under the hood, I can hear a sucking sound as the throttle valve (butterfly) opens, then there is a slight delay and the motor revs up.
I realy noticed the delay when I had the front driveshaft off and in drive. I would floor it, there would be a sound like a knock, then it would rev up.
With the front driveshaft on, I don't hear or feel the delay.
When in the cab and in "N" and I floor it, I can hear the like overload then rev up.

Could this delay be the VAF meter? The 95+ 1fz doesn't have the VAF meter does it?

Is this normal? Am I normal???
 
cruiserdan said:
Man,


That's a great long valve cover..........:D


Could you imagine this engine as a NINE liter V12?


Prolly 400 horse and 500 lb-ft torque....:D
Click to expand...


I think the price of gas just went up with that thought!!!!!!!!!!!!!!!!!!!!

BTW, how the heck do I get the little amionics back. I don't seem to have the option for them?

Cary
 
If the #2 PCV hose is only to vent the crankcase:
Why couldn't I remove the hose, plug the port on the throttle body and put a filter on the valve cover to vent it?
If the #2 PCV shouldn't have vacuum, would I cause any vacuum or lack of vacuum to the motor or crankcase?

I did run the motor without the an airfilter and I still had vacuum on the #2 PCV port on the throttle body and it did run rough like it did with the TRD filter installed.

Could I have a problem with the VAF meter. If it was sticking, wouldn't it cause a vacuum at the #2 PCV vacuum port at the throttle body?


The $20 Catch Can http://srt4.thebatanesislands.com/mysrt4/gal_20bux_catch_can_060203.html
I was thinking about taking the air dryier off the compressor but I didn't think it would work for oil and I didn't think it would work with vacuum.
But reading the link changed my mind.
 
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Thanks for the correction of the nomenclature


First time you said VAF I thought you meant MAF, but now 2 times, what is a VAF? is that what the door type MAF on the early trucks is called? The later trucks have a hot wire type, Maybe the door on the early MAF sensor makes more vacuumed as it blocks the intake path where the later types does not

Only problem I see with venting the crankcase to ambient is now PCV air is getting into the intake via hose #1 but not being counted by the MAF where before it was. This would lead to a lean condition especially at idle, the O2 might compensate for it in closed loop but not sure about open loop

Another way to do it is to block off both ports on the intake and just vent the engine overboard, that way no oil gets into the intake track, this would be better for the truck but worse for the environment, and illegal but even if they do look under the hood only those very familiar with the 80 would be able to tell


If you are getting vacuum at hose #2 port on the intake then surely air is moving the right way, why is oil getting into that line?
 
VAF Volume Air Meter. Ita a door that flaps in the wind of the intake system. Its mounted on the air cleaner.

<If you are getting vacuum at hose #2 port on the intake then surely air is moving the right way, why is oil getting into that line?>
When I remove the #2 hose from the valve cover there is enough vacuum to suck liquids: oil, seafoam
I then put my thumb over the open #2 port and I get a slight vacuum, this is from the #1 PCV hose.
If I remove #1 and hook up #2 I get vacuum when I put thumb over the port.

I think I got it now.
As #1 PCV is past the throttle plate/valve/butterfly there it needs to have vacuum going in one direction, thus the PCV valve. It keep the #2 PCV from robbing air from the intake chamber.

The #2 PCV is before the throttle plate so it can have vacuum in both directions.


Removing the PCV system:
It will keep oil out of my motor.
But what about removing moisture and any gasses, will they vent out on there own?
Will moisture work its way into the motor through the vents?
Then there is the smell to deal with.

I could put the PCV catch pan on both hose as an alternative to removing them.
I wounder if my one qt of oil per 1500mi could mostly be going up the PCV system?

On semi's , they vent the crank case out a pipe. On some semi's they get quite a but of smoke out of them. The new ones are going to have PCV systems on them along with an EGR system.
 
landtoy80 said:
VAF Volume Air Meter. Ita a door that flaps in the wind of the intake system. Its mounted on the air cleaner.
Click to expand...

OK so VAF is the old style MAF,

I put my thumb over the open #2 port and I get a slight vacuum, this is from the #1 PCV hose.
Click to expand...

This is good, the #1 hose and PCV can keep up with blow-by so it is working (at least at idle)

If I remove #1 and hook up #2 I get vacuum when I put thumb over the port.

I think I got it now.
As #1 PCV is past the throttle plate/valve/butterfly there it needs to have vacuum going in one direction, thus the PCV valve. It keep the #2 PCV from robbing air from the intake chamber.

The #2 PCV is before the throttle plate so it can have vacuum in both directions.
Click to expand...

Not quite, you will always have more vacuum after the throttle plate than before it on a running engine (well not during a backfire) that alone prevents the #2 hose from stealing air form the intake, the #2 port has more pressure, the PCV valve closes only during backfire to keep blow-by gasses in the crankcase from igniting, the rest of the time it regulates the flow of air to match changing vacuum in the intake



Removing the PCV system:
It will keep oil out of my motor.
But what about removing moisture and any gasses, will they vent out on there own?
Will moisture work its way into the motor through the vents?
Then there is the smell to deal with.

I could put the PCV catch pan on both hose as an alternative to removing them.

On semi's , they vent the crank case out a pipe. On some semi's they get quite a but of smoke out of them. The new ones are going to have PCV systems on them along with an EGR system.
Click to expand...

As long as the vent hose is clear and not plugged gasses & moisture will vent just fine, moisture would not get in any more than before as long as the hose is routed to a good spot, before the EPA changed things, auto engines were just vented overboard like the semi’s

I did not think about the smell (un-burnt gas and oil) , maybe the dual catch pan would be the best way to go,
I wounder if my one qt of oil per 1500mi could mostly be going up the PCV system?
Click to expand...

I have the same question about my consumption, my #1 hose has quite a bit of oil in it,

Good reading:

http://www.autoshop101.com/forms/h63.pdf
 
Is oil sucking realy a problem?
Does the little oil that gets in the intake system have any affect on the motor?
 
landtoy80 said:
Is oil sucking really a problem?
Does the little oil that gets in the intake system have any affect on the motor?
Click to expand...

A little will not do much harm but a lot can lead to deposits, I think the oil and the EGR gasses are the major parts of the thick junk in the intake manifold, this gunk will also be form on the intake valves if the fuel detergent sprayed on the valves cannot keep up, can also lead to deposits on the piston and bottom of the head
 
I got a new #2 pcv hose as the old one was hard and cracked. It may of been my lean/rich problem.
The new hose is soft rubber unlike the old one. Its soft as a limber :censor:
 
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