Cylinderhead ventilation - greasy plenum...

[Lt86]

Hi everyone,

I was wondering if anyone has the same 'issue' I have... When I took off the throttle body to clean up my auxilary air valve I noticed the throttle body was rather greasy on the inside from oil and so was the plenum chamber.

Now, I don't know where this is coming from but I believe it might be from the cylinderhead ventilation tube (see red circel below) that connects the head with the plenum chamber.
Anyone else who has this issue? If not... where could the oil be coming from?

[Ivan141]

That's the crankcase ventilation, so yes, it will contain oil fumes on worn engines.
You can put a catch can in between to avoid the oil entering your plenum.

[oldeskewltoy]

In longitudinal installations, on long moderate to high "G" load left turns it is possible to fill up the head with oil and then the breather acts more like a spout that pours oil into the intake.

The easy answer to this problem is to add a drainage port on the rear of the intake side of the head, similar to the smallport heads drain. Once you do this there is far less chance of filling the head to the level that it pours into the intake tract.

[Dave W]

After rebuilding my 4AGE 16V motor, including new valve guide seals I used on average about 1 Qt of oil per 1,500 miles. A few years later I pulled the intake manifold off to install a thermo gasket between the head and manifold. What I found in my newly rebuilt engine, was a lot oily $hit in the ports and head. I was running my oil breather tube “stock size” to a small one pint dump can then back to the intake manifold. But I was drawing such a high vacuum that engine oil was being suck into the motor thru the intake system. I changed the breather system to run straight to the atmosphere. I then took a 1,700 mile trip and I did not have to add a drop of oil. The 4AGE motor needs a larger then stock breather hose and a BIG dump can for the engine breathing system. A 2nd option would be to install a real PVC valve on thr breather hose. Dave W

[totta Crolla]

(03-31-2015 01:22 PM)Dave W Wrote:  After rebuilding my 4AGE 16V motor, including new valve guide seals I used on average about 1 Qt of oil per 1,500 miles. A few years later I pulled the intake manifold off to install a thermo gasket between the head and manifold. What I found in my newly rebuilt engine, was a lot oily $hit in the ports and head. I was running my oil breather tube “stock size” to a small one pint dump can then back to the intake manifold. But I was drawing such a high vacuum that engine oil was being suck into the motor thru the intake system. I changed the breather system to run straight to the atmosphere. I then took a 1,700 mile trip and I did not have to add a drop of oil. The 4AGE motor needs a larger then stock breather hose and a BIG dump can for the engine breathing system. A 2nd option would be to install a real PVC valve on thr breather hose. Dave W

Was this with a stock bigport engine on TVIS inlet manifold ?

[krullibull]

Or if you can live without the sparkplug cover, just flip the covers. Did this on mine and it made a big difference!

[Lt86]

(03-31-2015 01:22 PM)Dave W Wrote:  After rebuilding my 4AGE 16V motor, including new valve guide seals I used on average about 1 Qt of oil per 1,500 miles. A few years later I pulled the intake manifold off to install a thermo gasket between the head and manifold. What I found in my newly rebuilt engine, was a lot oily $hit in the ports and head. I was running my oil breather tube “stock size” to a small one pint dump can then back to the intake manifold. But I was drawing such a high vacuum that engine oil was being suck into the motor thru the intake system. I changed the breather system to run straight to the atmosphere. I then took a 1,700 mile trip and I did not have to add a drop of oil. The 4AGE motor needs a larger then stock breather hose and a BIG dump can for the engine breathing system. A 2nd option would be to install a real PVC valve on thr breather hose. Dave W

Well, this is my concern. If I put a piece of cardboard behind the exhaust it starts to decolour from the spray caused by the exhaust (at idle!). Even though it could be my cylinderhead needs a rebuild, I was very surprised to see how greasy my plenum was. For sure this is sucking in oil. Thing is though, I don't have a dump can in between the breather hose from the head to the plenum so I don't know why it would draw so much oil.

So running the hose straight to the atmosphere with a small airfilter on the end would be OK? I would block the plenum opening on the other side.

[Deuce Cam]

After 30 years it's going to look pretty nasty regardless. I wouldn't worry about it unless you're going through a lot of oil between changes.

[allencr]

(03-31-2015 05:49 PM)Lt86 Wrote:  Well, this is my concern. If I put a piece of cardboard behind the exhaust it starts to decolour from the spray caused by the exhaust (at idle!).
I don't know what you think that means, but whatever, you're wrong! It's 100% normal for any IC engine out there.

So running the hose straight to the atmosphere with a small airfilter on the end would be OK?
To filter what? It will only keep bugs from crawling in.

What's the compression? How many miles/kilometers????????
Yes it's oily, it's a tired old engine with blowby & completely normal, and venting to atmosphere could change the consumption a little.
.

[Lt86]

(04-01-2015 09:06 AM)allencr Wrote:  

(03-31-2015 05:49 PM)Lt86 Wrote:  Well, this is my concern. If I put a piece of cardboard behind the exhaust it starts to decolour from the spray caused by the exhaust (at idle!).
I don't know what you think that means, but whatever, you're wrong! It's 100% normal for any IC engine out there.

So running the hose straight to the atmosphere with a small airfilter on the end would be OK?
To filter what? It will only keep bugs from crawling in.

What's the compression? How many miles/kilometers????????
Yes it's oily, it's a tired old engine with blowby & completely normal, and venting to atmosphere could change the consumption a little.
.

I'm not wrong on this one. There is just to much spray from the exhaust. I have many other cars but none of them spray this much... .

No idea about the compression but will test soon. The engine has about 120k km.