fastnoypi

I am trying to understand your view on how the timing belt can possibly be soaked with oil before ending in the intake.
From member pictures and that on Toyota nation, the baffle in the rear valve cover will cake up from dirty oil. This creates a high pressure situation in the oil pan to push oil from the oil pan up to the pcv and into the vacuum of the intake manifold to be consumed during combustion.

As an analogy, think of pot of boiling pasta on a stove , the water will be controlled and steam out vapor. If you boil the same amount of pasta with the lid on or just slightly off at the same heat, you'll find pasta water all over your stove. The vapor pressure pushed the water the path of least resistance.

here is a reference article that talks about breathers in general, but it also applies to the internal breather built in by toyota. http://www.ehow.com/how-does_5063486...hers-work.html

salimshah

I dont have any issue with splatter and vapors through the pcv-orfice-tube.

Then again look at the size of hole and how much splatter can make the bulls eye.

Air intake through the filter produces a little suction through pcv (there is high a low pressure that sucks the unburnt fuel vapors ... normal action of pcv). There is no straw like suction which is deep enough to reach standing oil level. One can make an argument that the oil level reaches all the way up to top of the valve cover. [this can possibly happen if the drain lines are clogged due to sludge. If we get to that point then the oil will leak from front of the cam gear (among other ... like tubes for spark plug).

So only way for substantial (more than splatter and vapors) oil to end up in the intake has to be from reverse flow from air inlet valve.

The other evidence that I present is that if there was a design flaw then all engines with exhibit the oil in the intake problem.

If you present the argument that after the valve cover change the problem went away. I will counter that with at least one member noticed no change.

At the end, all I am saying is that it does not make sense how substantial volume of oil is going through intake through the valve cover.


Salim

fastnoypi

a problematic RX can easily demonstrate a high volume of oil reaching the intake via the rear valve cover pcv by putting a catch can inline.

tllee

I think that you have a wrong idea about how oil get into the intake. It's not necessarily "the oil level in the valve cover must get as high as the intake". What happened is the baffle plate inside the valve cover didn't do its job to limit the blow-by been sucked into the intake. The PCV valve sure play some part of this flaw too but baffle plate is the major role.
I has done the experiment already. I installed an oil catch can on my RX300. The blow-by is almost fill my can(750ml) in 20 miles driving at 75 MPH. But it's very little amount when drive at low speed(not higher than 50 MPH) but if your pipe or PCV valve get pluged, it will suck in blow-by at low speed. Please understand this, blow-by is mixture of gas,oil,water,etc.... So probably 10%( my guess) of blow-by is oil, that's reason why we lost 2-3 qts oil in 200 miles driving.
Let me ask everybody a simple question, how many of you drive very short distant(1-3 miles) every day or every 2-3 days? My guess there aren't too many. Unfortunately, I'm one of the few. That's the cause of this problem, so not every car has been plagued. I am not the car engineer but neither are you. Even car manufacturer keep making mistakes, that's why so many recalls.
I won't be so firm about somebody's idea is wrong b/c of my mind couldn't comprehend. If everybody is so insist on their own idea, we shouldn't have this forum, because nothing need to be discussed here.

tllee

Exactly!! I done that already. My oil catch can sucked in almost 750ml of blow-by on 20 miles driving at 75 MPH. The blow-by contain certain amount of oil(10%? may be), that's how the oil(with all the "stuffs") travel to intake and burned without trace. That's original design idea of PCV system!! RX300 have 3 catalytic converters, they can handle this amount of blow-by burn. But I'm not so sure about the long term effect. So I changed my rear valve cover.
Also I think this problem may be one of the causes for oil sludge(only my theory). Image this, the oil pressure light won't come on even oil down to 2 qts in your engine, you didn't check your oil for 2 months, what is the outcome? SLUDGE!!
Toyota is savvy, they keep good things, the water pump never been changed for 1MZ engine, they even use it on some 3MZ engine(or all of them?). If the rear valve cover has no flaw, why change its design? It cost money. Recall for sludge problem cost a lot, so old valve cover has to go.

tllee

Let me explain how "substantial volume of oil" is going thru intake. First, you must understand how the PCV system work, I'm assume that you're well aware of it.
PCV valve allow blow-by to suck into intake and burn it with air-fuel mixture. It prevent the air pollution. Blow-by contain some oil and a lot of other "stuffs", if the blow-by been sucked in too much,abnormal amount of oil disappear too.

That's reason why, we still need to check oil on a no-problem engine routinely because the normal amount of oil will disappear and it's within the tolerance(not 2-3 qts).
If it's as you suggest that "There is no straw like suction which is deep enough to reach standing oil level"; " how much splatter can make the bulls eye", we should never check our oil level if no leaking on outside of the engine.

Sure the vacuum can't suck oil directly from oil pan. But the vacuum in this problem engine can suck in a lot of blow-by, pull off your PCV pipe on PCV valve side and raise RPM of your engine, you'll see how big the vacuum is(put your finger on the pipe end). If you want to know how much blow-by can be sucked in? Install an oil catch can, you'll believe me. Fortunately, your engine has no problem(but not everybody's), so you can't do this experiment( i did it already).

One more thing, I had a Honda Odyssey which received a recall for the infamous transmission problem, before 100K miles a lot of owners have their transmission rebuilt due to this issue. But a couple of my friends run this van up to 200000 miles without any transmission issue.
Can they claim that problem is not exist because their transmission is not plagued? It's a simple logic, hope you understand(no offense).

kalali

The sludge issue and the design flaw in the rear valve cover on these engines are well documented and even acknowledged by the manufacturer. Occasional long high engine speed drives along with frequent oil changes tend to be effective preventive measures.

salimshah

If the drain is not happening due to gel then the oil level will rise and can be sucked in by intake, else it will be the splatter or vapors. The same principle applies if the oil pump is outpacing the drain.

Please list the reasoning to help me understand?

My mental block is, what is the underlying physics.

Salim

tllee

Please see this link:

http://www.toyotanation.com/forum/83...r-fixed-2.html

The pictures are very clear and could have the answer you want. Please see how close the baffle plate to PCV valve hole! The most of the blow-by should be condensed to liquid form and flow back to bottom oil pan, if it is not fast enough(it will stay between the baffle plate and valve cover top, not oil pan or upper engine block), then it will suck up by the vacuum to intake. My oil catch can prove it, I was using a transparent tube, I can clearly see the condensed blow-by pass through it! I wish I took a video but I was so urge to change my rear cover to avoid any damage(some guys experience a valve damage, he claim that cause by this, I'll rather believe it than prove it myself.) Hope this will help.

Baetke

There is another way that oil can get into the intake that hasn't been discussed yet.

If the PCV valve is stuck shut the pressure that builds up in the crankcase will backup through the breather hose and the fumes will go into the intake upstream of the throttle body. The breather hose runs from the forward valve cover to the intake tube between the air box and the throttle body.

fastnoypi

Salim, here is a diagram that might help understanding.


The picture on the left demonstrates the pressure build in the crankcase of our RX's..The left most valve cover is our rear valve cover.

The pictures on the right demonstrate the correct positioning of the pcv valve during normal operation at idle and at speed.

When the rear valve cover baffle gets clogged, the crankcase pressure and oil in the oil pan gets whipped up and tries to find the path of least resistance. Two paths that it can take.
1) through the drainage holes of the front head..into the baffle of front valve cover ..and into the breather which connects to the RX airbox.

2) through the drainage holes of the rear head..into the baffle of the rear valve cover ..through the pcv valve and into the intake to be burned.

When sludge builds up between the baffle plate of the rear valve cover, There is not enough oil gap for the oil to separate and drain back. The high pressure situation will force the pressurized oil through the pcv.


Plans for my replacement of my rear valve cover didn't happen this week, i hope to get pictures of my original rear valve cover and compare the baffle to the improved design next week.

salimshah

Thank you for the posts.

So the theory being presented .. the oil (foamed oil or what ever) rises above the
a) rear valve cover
b) front valve cover
OR both a) and b) and enters the intake.

Evidence:
Once it gets into the intake, it makes it way to chamber and gets burnt. Depending on amount of oil that gets in the intake, we should see oil (blue/dark smoke) out of the exhaust and plugs. Soot on the rear bumper near exhaust. If one opens the intake, there should be oil in there (more than the slight brown residue (gum) from the fuel.

Another clue: The compression should be reasonably good as the smoke should not be due to oil from the other side of the piston.


How is this as a stake in the ground?

Salim

fastnoypi

by toyota/lexus design..in theory the oil can eventually enter through the intake via the front valve cover...but in reality it will not pass due to the air filter being in the way if you trace the breather line into the air box.

Agreed, depending on oil amount and burn, blue/dark smoke may be visible out the exhaust and on the plugs though a higher un-likelihood on the plugs due to oil distribution in the v6 intake manifold airstream..
Soot may be hard to determine due to the location of the muffler and oem exhaust tip angle. If the catalytic converters do not get hot enough, an occaisional puff of smoke may be visible.
If one opens the intake, brown residue gum will be from the oil blowby. Fuel does not enter the intake manifold. It is introduced via injector directly into the intake side of the head.


If by "other side of the piston" you mean the combustion side, yes compression should be reasonably good if oil has not been lost to a critical level. Under normal operation, oil on the back side of the piston will lubricate the piston in the bore.
If oil levels are too low, the piston oil rings will not provide enough lubrication in the bore. The top and secondary compression rings will heat and wear the sidewalls of the bore till compression is lost.

fastnoypi

Pictured are the original valve cover and new design aka rx330 valve cover.
Unexpectedly i could not find any signs of sludge that was causing high oil consumption though i do have discoloration due to varnish.

Note the design differences in the baffle, sorry for the small cellphone pics, this is where i suspect the higher likelyhood of where the oil consumption is caused.

In the original valve cover there are 3 breather holes for the baffle plate on the bottom surrounding the #3 sparkplug tube hole. If you line that up with the cams, you can see how the cam lobes can sling oil directly over the breather holes to be sucked in by vacuum.
The new valve cover keeps the breather shrouded to the left of the #1 sparkplug tube hole where no oil can be slung by a cam lobe.

The cam lobes sling oil to keep the valve buckets lubricated as well as their neighboring cam lobe when they rotate.

matts6887

fast; is that pic of the valves in the front or rear valve covers?