Crankcase ventilation

[vristang]

Has anyone had to use a restrictor on the TB/valve cover line, to minimize flow?

I have installed an oil seperator, which works well.

However I am still suffering from idle problems, similar to a vac leak. When I pinch the line between TB and Valve cover. the idle drops.

Any thoughts?

 

[90bluecoupe]

It all depends on what kind of oil cap you have.If you have the breather type then you need to cap off the tb and valve cover others there is nothing but a big vac leak.

 

[vristang]

Stock type ventilation system. So I have a sealed cap.


Just getting too much air flow I think.

 

[HISSIN50]

Jason, let's see if Don posts. He has posted pics of a restrictor he uses or used.

He is the only one I can think of who has used a restrictor.

Good luck bud.

 

[luckythirteen13]

get rid of the hose all together. its just a way for the engine to suck up a bunch of junk. put a vac cap on the tb and on the spot on the valve cover where it hook up to. then take the oil cap off and stick a breather in it. this way the air can still vent out but you no longer have it hooked up to the tb. ive seen it done many times. i dont use the stock valve covers anymore so its not a problem for me

 

[vristang]

get rid of the hose all together. its just a way for the engine to suck up a bunch of junk. put a vac cap on the tb and on the spot on the valve cover where it hook up to. then take the oil cap off and stick a breather in it. this way the air can still vent out but you no longer have it hooked up to the tb. ive seen it done many times. i dont use the stock valve covers anymore so its not a problem for me

I first read this at work and thought "No Way, am I removing the hose all together". Here is why I thought that...
That hose allows fresh air to enter the crankcase. That fresh air travels through the crankcase and out the pcv. During its journey the fresh air picks up water vapor, blowby gasses, and a variety of other harmful substances in the crankcase vapor. Without that tube running from the TB to the valve cover, there would be a build up of these substances in the crankcase, which will destroy the oil and eventually the motor.

However, this system assumes there to be some mentionable amount of blowby. I am using Total Seal Gaples top rings. I did a leak down test a few weeks ago (with the motor cooled for several hours, and the rings may not have been fully seated yet) and came up with only 6%. Not much blowby here at all.
Is it possible that I could cap off this line and rely on the engine vac. to fully purge the crankcase through the pcv?
If my vac was not as strong as it is I would not even consider this. But, with 17-18" at idle, I am thinking it just might work.

Is there anything I did not think of?

 

[vristang]

So unless someone steps up and says I am a fool here is what I am going to do...

I will block of the nipple on the valve cover and on the TB with vac plugs. I will then be relying on engine vac to vent all of the harmful fumes from the crankcase, without the fresh air flow.

This should solve my vac leak issues, and I imiagine it will cut down on the oil that is getting trapped in the seperator I installed between the pcv and the intake, by reducing the volume of airflow.

I figure that if I leave the vac plugs in place, I will be able to tell if I am getting a large amount of pressure in the crankcase as well. If crankcase pressure gets high it will pop the vac cap off.

I will do this immediately after work so chime in quick if you think I have completely lost my marbles. You have 3hrs.

 

[1EVIL88VERT]

if your going to cap off the T/B line then you need to get a breather to go on your valve cover( in place of your oil cap) , so that you can still have air coming in the crankcase while its getting sucked out of the pcv....

 

[darthcual]

Are you going to use a breather cap in place of the oil cap? this is what i'd do. Good Luck.

 

[HISSIN50]

J, check out these threads for some ancillary info. Read Don's replies:

Here is one.

And here is another.

Good luck bud.

 

[vristang]

J, check out these threads for some ancillary info. Read Don's replies:

Here is one.

And here is another.

Good luck bud.

I checked out the links, and I think I will try the restrictor first.

Thanks

 

[HISSIN50]

Sounds good Jason - it is a little less extreme. Good luck.

 

[vristang]

Well I went with JT on this one. I went to the parts store and picked up a vac line adapter that had an opening about 1/8". I spliced the adapter into the TB/VC line. The car seems to idle a little better, but still not as steady as it should be, even with the cam. I will give that some time though, as I only put the seperator on the other day. I am probably still burning oil residue out of the chambers.

I would not have put a breather cap on the valve cover though. The entire idea of closing that off is to stop airflow into the crankcase. Then the engine vac would only pull the volume of blowby gasses out of the crankcase. As it is now (and it would be the same with a breather cap) there is unmetered air (heavily contaminated with oil) entering the intake manifold via the pcv. This unmetered air is killing my fuel economy/power/idle. If things don't get better with this setup I will keep looking into capping off the valve cover. I don't see any other way to get the volume of air passing through the pcv down to a normal level.

Tomorrow after work I will hit the TB with some spray cleaner, and make sure the tps is set at the lower idle. It is running better now, so I am still hopeful this will work.

thanks for all the advice guys.

 

[bobbys9350]

what excactly is an oil seperator? thanks!

 

[HISSIN50]

what excactly is an oil seperator? thanks!

It is sort of like a filter for the PCV gasses. It is installed in series with the vacuum line from the PCV valve to the upper intake. all the blowby passes through the separator and the oil is knocked down into the separator's basin, allowing the 'less heavy' air to pass on through the separator's outlet bung and into the upper intake. This helps to keep oil out of the intake.

I just took a look at mine today. I initially had a teaspoon make it in there and now not much more. Interesting.

 

[vristang]

Well the restrictor seems to be working well. It took about half a tank of fuel (with fuel system cleaner) to get the residue out of the system, but I have hit the throttle hard several times now, and have yet to see any puffs of smoke from the pipes.

Eventually I wil get a pic of the restrictor posted so you guys know what worked for me.

I don't seem to be adding any more oil to the seperator either, but I will leave it in place for a while, just to be sure.

I want to thank everyone who posted here and offered their advice, I do appreciate the help.



Thanks again JT

 

[HISSIN50]

Well the restrictor seems to be working well. It took about half a tank of fuel (with fuel system cleaner) to get the residue out of the system, but I have hit the throttle hard several times now, and have yet to see any puffs of smoke from the pipes.

Eventually I wil get a pic of the restrictor posted so you guys know what worked for me.

I don't seem to be adding any more oil to the seperator either, but I will leave it in place for a while, just to be sure.

I want to thank everyone who posted here and offered their advice, I do appreciate the help.



Thanks again JT

Jason, glad to hear that is working. I was hinky about you having a one-way PCV set up (people end up with air getting sucked IN through seals).

And you cant thank me for anything - I was just the messenger. Don is the one to thank.