Originally posted on November 15, 2009, on another forum
Warning, American English used!

I went to the junk yard a few months ago and decided just for grins to take apart a valve cover off an old FS-DE in a GE 626 to look at what it is like inside

I was surprised to find the lack of baffling on the PCV valve side and a poor baffling design on the breather side... all it was were a couple of compartments with a tiny 4mm hole for air to pass in between each one of them... while it would work to some extent as an oil separator, it is obviously a piss poor design! there's not much of any way for oil to condense and drain itself back out into the engine

now imagine if this was all on a boosted engine... under boost, the blowby will just shoot itself out through the breather side and out into the intake... the suction from the turbo helps exacerbate this too


here are some crappy cell phone pics I took of the valve cover... the green shaded box is a halfassed impression of the air scoop at the bottom of the valve cover plate that feeds vapors/air to the PCV valve... the red arrows obviously are the PCV vapor path.. the blue arrows are fresh air from the breather hose hooked up to the intake (normally)
the diagram depicted is normally under OFF BOOST conditions... the path reverses when under boost... and if a good PCV valve was installed, there should be no airflow going through the PCV side (which thereby boosting the crankcase)... but blowby occurs anyway, and will force vapors out through the breather side



I believe what needs to be done to truely fix this oil burning problem once and for all is to come up with a way to KEEP the oil in but allow air to come out... you don't want to plug this up because it will blow up the seals and cause a leaky mess!

the PCV side is relatively easy... a simple stainless steel pot scrubber pad should work as a temporary means to condense oil and let it drain the collected back out (like under boost or when engine is off)... the breather side isn't... the space is small and due to the separate compartments, there's no easy way for oil to just drain back out into the engine... stuffing scrub pads in there isn't a long term solution... what might end up happening is the chambers get flooded and oil will piss out after some time without any means of going back into the engine

the most likely possible solution (which I don't have the means of personally achieving at this time) is to machine new covers or modify existing ones and weld on baffle plates to it to catch oil and somehow allow it to drain out

doing this ought to eliminate MOST of the oil escaping out the breather hole under boost as well as oil going into the PCV valve under cruise conditions...
achieving this will allow a simple 30 minute fix to any protege without going through other expensive means like an oil catch can (not a good solution.... imagine a couple of laps around the track and all your oil is in the catch can and NOT the engine), or an oil separator tank (which means welding a bung on the oil pan to allow for separated oil to drain back to the engine)


FWIW, other engines like the Volkswagen VR6 motor have a pipe cleaner looking thing that is installed inside the valve cover's breather system to act as an oil separator... poor quality oils or lack of oil changes caused sludge build up there (as well as other parts of the engine of course) first and made the engine run like crap... other engines like American ones have a oil separator/filter that is installed right on top of the valve cover inline to the breather hose... BMW uses a factory oil separator system that drains oil back through the dipstick tube... I have yet see a japanese engine that have any of these superior characteristics... cheap bastards!

Recently, there was a discussion on the Miata board regarding their BP valve cover's baffles and modifying them to help reduce oil consumption. Linked from that thread was this how-to: http://mx5unleashed.com/tech/valve-cover.html
I followed its ideas but modified it to suit my needs.

Yesterday I went ahead and did the valve cover mod... it was a b*tch because of the cleanup involved, the modification part was easy... cleanup sucks!!!

Buying the materials involved wasn't exactly easy. No store here carried washing machine discharge hose lint traps, of any kind. I special ordered the aluminum ones from Ace Hardware for less than 4 bucks with tax. Took about a week to get them. Then I bought a pack of Scotchbrite stainless steel pot scrubbers from Home Depot for just a little over 2 bucks.


So first I took the valve cover off and laid it on a clean smooth surface to keep the top side from getting messed up. I took off my JDM Mazdaspeed oil cap also to prevent damage also.


I removed ONLY the large baffle cover carefully. The RTV silicone sealant sticks to the steel cover like glue and in order to keep it from bending, I pried it off slowly with a small pry bar alone the entire length. Pulling on the cover as I pried on it.

Now came the hard part.... clean up! I scraped off the old black RTV sealant with a razor blade then cleaned the rest up with a rag soaked with brake cleaner. The pieces of sealant clings to the cover really well and it was very hard to get 99.9% of them out! In the process, I also made sure I cleaned out the sludge in the area right around where the PCV valve goes. Despite using synthetic oil, a slight build up was still there. Not entirely surprised.

After more than an hour cleaning up the valve cover and being higher than heaven on the brake cleaner fumes, I finally stuffed the valve cover's baffles with the "oil separators":

For the PCV side, I massaged and stretched one of the Scotchbrite pot scrubbers to a long sausage shape, then I carefully placed it inside the lint trap sack. It wasn't easy because the lint trap tends to collapse on itself. I also didn't want to put too much force because the lint trap is aluminum and the thin wires can break easily. Hindsight, it probably would have been easier to first roll a piece of paper around the pot scrubber and slide it into the lint trap and then pull the paper out in order to avoid snagging. Anyway, the idea of using the lint trap sack is to help keep the pot scrubber from coming apart and help trap oils better. Then I tied up the sack's opening with a piece of aluminum safety wire. Both ends of the sack are folded towards the center as shown in the pic. I also inspected the lint trap sack carefully of any broken wires and removed any loose pieces found. This was very important because I don't want any of them going into the engine!!!

For the breather side, I just simply stretched and stuffed one Scotchbrite pot scrubber into the baffle. No lint trap needed and no space for it anyway.

Finally, I drilled a 1/16" (1.5mm) hole in the breather side of the baffle cover. Right at where the 2nd air passageway is. This is to allow oil to drain back into the head while the small hole doesn't cause any major air flow disruptions in the PCV air exchange system.

Unlike the MX-5 Unleashed how-to, I did NOT cut any notches in the valve cover itself because of the differences in the FS's valve cover design. A notch will cause oil to pool over to the outer baffle and cause oil to easily get blown out the breather hose under boost.

Then I closed it back up using liberal amounts of black RTV silicone sealant. Sealing all divider walls just like it was originally, again, unlike the MX-5 Unleashed how-to. New valve cover gasket and Mazda branded Dow Corning SH780M gray RTV silicone sealant used on the valve cover gasket humps over the cam caps of course.

I put about 15 miles on the car so far, with lots of boosting and engine braking. The PCV valve remains dry so far! It will take me many months to see if this really works because I don't drive my car often, but I'm confident it will cut down oil consumption a lot. I was only burning half a quart every 3000 miles, so it wasn't not too bad, just annoying.

really good guide