Zetec and PCV valve

[James A]

Ok, a little bit of a long explanation; I have a Zetec Caterham, it has a 1998 Zetec. From day one on the track and autocross it smoked heavily in right hand turns, the cause being the PCV is on the left side of the engine and oil would climb the block and go though the PCV and oil separator and back into the intake. Athens7 installed a catch tank between the PCV and the intake to catch the oil and eliminate the smoking, great idea and I copied his design. So, yesterday I took the car to Motor Sport Ranch Houston and we were running clock wise so a lot of right hand sweepers and turns, good I can try out my catch tank. The great news is no smoking at all! The bad news is after 2 twenty minute sessions I had almost 1 quart of oil in the catch tank!

Surely, this is not typical of the Zetec, so what is the solution? Who has a breather system that doesn't puck oil out like crazy? I just can't believe that everyone with a Zetec puts up with the smoke or putting a quart of oil in the engine every 40 minutes.

Help!

[Eraser-X]

I also seem to have the same issue with my Birkin but not on all tracks. If I run at the driveway in Austin a very sticky track with lots of high g turns and braking my catch can still pretty dry. If I run at Harris Hill road in San Marcos in either direction I get about 12 ounces of oil in the catch can per session.

 

I was starting to think that is was because Harris Hill was so bumpy. But now I am starting to think it is just an issue with the design of the valve covers breather assembly.

 

Either way I need to find an acceptable fix I am on the track at a couple of times a month and Harris Hill has just been repaved so anything that helps me avoid draining that catch can between sessions would be a great help.

[scannon]

How about running a drain line from the catch can back into the sump?

 

The factory Mazdaspeed turbo Miatas have some type of separator in the breather line that extracts the liquid oil and runs it back into the pan. No actual catch can but the idea is the same.

[pi7ot]

I was running the PCV system like stock.

The crankcase pressure would tee into the intake and the valve cover emissions went into a catch can.

This worked for a number of years on clockwise tracks without incident.

Then this problem surfaced.

A new pcv valve did nothing. The catch can was filling with oil.

The oil was not overfilled, it just has excessive crankcase pressure.

Things came to a head (literally) as the oil was accumulating in the cam valleys and drowning the cams. You could feel the engine laboring worse each successive lap. :sadangel:

I'm going to rebuild the bottom end as I think it is a ring sealing/flutter issue.

Some have suggested a post rebuild sealing the bottom pcv port, but I'm concerned that the oil would not be able to return to the sump.

 

m

[athens7]

After 4 runs last Sunday, I had almost 1/2 quart of oil in my catch tank. Certain tracks (high G right turns) can really force oil out of a Zetec. My understanding is that the road race guys just put a block off plate where the PCV valve used to be. As the PCV system is primarily an emissions control device, I have been told eliminating it is not a problem on race engines. The reason I retained my PCV system was because I use factory engine management and felt it would be better to keep operating parameters as close to OEM as possible. Also, I felt oil loss would be minimal in my autocross application.

[slomove]

There has been a long discussion recently on the Birkinowners list with exactly this subject. Conclusion was kind of there is no single root cause but some contributors are (or are suspected):

- in general the fact that the engine is installed lengthwise while designed to be across. Right hand turns will push the oil up the left hand sump wall.

- some ZX1 engines did not have the windage tray installed, causing excessive sloshing

- high oil level in general

- worn rings or ring flutter, causing lots of blow-by, pushing the oil droplets out of the PCV (and valve cover).

- too small PCV vent hose. The higher blow-by escape velocity may not allow the oil to drop out and drain back in the hose.

 

Blocking off the PCV may help oil spitting but there is a risk of pressurizing the crankcase and valve cover, if the valve cover vent is too small to handle the blowby (I had oil seeping out of the valve cover after doing that). Some people suggested, the blowby going up to the valve cover inside the block may not allow the oil to drain properly from the cams into the crankcase.

 

So, the conclusion was:

- don't fill oil too high

- make sure you got the windage tray in place

- use a generously sized PCV vent hose (5/8" or 3/4") into the catch can

- use an additional large vent hose from the valve cover into the can

- make sure the rings are not worn, bores not glazed and piston landings not broken or rebuild the engine (I had to do that)

- check the second ring gap is a bit (25%) larger than the top ring gap (supposedly minimizes ring flutter)

 

After that I have very little fluid to drain from the catch can after a track session, maybe an ounce, including condensate water.

Edited October 9, 2010 by slomove

[James A]

I considered blanking off the PCV port in the block but an concerned about pressurizing the block and cam cover and getting blow by through the dip stick. I could easily run the com cover vent to the catch tank and drain the catch tank back to the block.

But again an concerned about some of the issues that Slomove brings up.

Jim

[Boxologist]

try this.

http://forums.nasioc.com/forums/showthread.php?t=2064580

[supersportsp]

I am interested in this conversation. After my second outing at the local kart track, I noted that I seem to be puking some fluids out of my carbs. I didn't think it was engine oil, not thick enough, but perhaps I am wrong. I am running DCOE's on a Zetec.

[pi7ot]

try this.

http://forums.nasioc.com/forums/showthread.php?t=2064580

 

Interesting.

You made me realize that OBD2 BMW M3 gen 2 models have what is called a cyclone separator.

It is a triangular shaped air/oil separator. It is cheaper than the scooby part but needs just a little modification to work on a different engine.

I have one laying around but I don't know if it is in working condition.

 

 

m

[James A]

After talking with a number of people and one person who races a Caterham in SCCA with a Zetec here is what I am going to do:

- Replace PCV valve with 3/4 inch OD tubing (PCV will act as a check valve and not let oil drain back to the block)

- Raise the catch tank as high as I can, in fact it is only about an inch under the bonnet now

- Run 3/4 inch hose from the tubing I replaced the PCV with and run it vertically up to the catch tank.

The oil that climbs out of the block will not be able to climb all the way up the hose to the catch tank inlet and with the PCV out the oil can run back into the block.

I am taking the Caterham to the track this Saturday and autocrossing it Sunday, if this works out, I will take pictures of my set up.

If it doesn't work out, back to the drawing board.

[supersportsp]

What was the result from this weekend's activities? Satisfaction or a return visit to the drawing board?

[James A]

The modification worked very well, there was no oil carry over into the catch tank, I believe the modification allowed all of the oil to drain back into the block. The one issue remaining is that the catch tank vent I have is very small and causing some venting from the block to the cam cover and some oil coming out of the vent on the cam cover. I have never had any oil come out of the cam cover vent. I think the solution is simply to increase the vent size in the catch tank for the block, this will be easy as I will install larger vent with a filter on it.

I will post some pictures of what I did as it seems to be the solution to oil carry over on hard right hand turns.

Jim

[pi7ot]

After my rebuild this winter, I'll be modding an S14 air/oil separator for use with the Zetec. I'll be drilling a hole in the sump for the fluid drain back fitting..

 

 

m

[focusinprogress]

I don't know if you found a solution yet, but C-F-M.com sells a pretty trick oil separator system that replaces the PCV system, it was designed for for focus.

[James A]

I was just sent a link to the CFM part and it is nice! and, comes with 1/2 threads on the outlet so I can hard tube or aeroquip the breather to the catch tank. I like the looks of the CFM part and may just give it a try.

Jim

[Jackal]

Back from the dead.

 

I wanted to follow up with folks that have used the cfm part or tried the S2 solution from the link on the first page. I was thinking of using a combination of both, but don't know if the S2 solution will fit between the motor and the hood.

 

Any pictures or details on various setups (zetec) is appreciated.

[pi7ot]

I rebuilt my Zetec and did not remember to do my separator mod. I ran 3/4" tube from the breather unit into a catch can.

Since the rings now seal tightly, there is very little crank case pressure, and no oil in the catch can.

As the engine wears, I'm sure I'll be working on this issue in the future.

 

m