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The OVS on my 74 Spider is shot so I started looking for a replacement. On the advice of another thread, I called Centerline and sure enough, they had just received a shipment of reproduced OVSs. They said they were all plastic and will last a lifetime. They are not inexpensive, but I went ahead and ordered one.

What I got surprised me a little. It is clearly a 3D printed part. It appears to have the same dimensions as the original, but is much lighter and has a rough feel. Looking inside the holes, I can see there is some sort of internal structure, but it's impossible to see what it is.

As I understand the operation of the OVS, the corrugated brass in the old design is important to the separation of the oil. I'm a little concerned that this new design won't be as efficient at accomplishing this.

I have to get the heater box repaired on my Spider before I can test this OVS, but in the meantime, here's a couple of pictures.
 

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There are a couple of threads where people have cut the OVS open and you can see what's inside. It's not that complicated really, there is a standpipe coming up from the bottom that rises into an inverted cup and to which, when you start the engine, intake vacuum is applied. This begins the flow of crankcase vapor into the upper offset inlet. The offset causes the vapors swirl around producing a centrifugal action which causes the heavier oil droplets to get flung against the outer wall and flow to the bottom where it is collected by the corrugated baffles and drains through the small tube back to the sump.

The problem is the corrugated baffles get clogged up, the oil doesn't drain properly and eventually starts getting drawn in to the intake. Why this wouldn't also happen with a plastic device I don't know but I have had good success cleaning these out with a propane torch - kind of the same principle as a self cleaning oven. Recently I have had success using an ultrasonic cleaner which will work with plain old water believe it or not. In fact there is a nice 2 liter heated one on Amazon for about $80. They can be used for many other things as well such as injector nozzles and such. They really do work.
 

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I hadn't thought of the propane torch approach, but wouldn't that still leave any corrosion crud in there? If the corrugated brass is gone, as I've seen in some of the photos on this topic, I don't think either the torch or the ultrasound would solve the problem.
 

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I clean mine on my 69 out every year or so by soaking it in mineral spirits and flushing several times. I also flush the oil return line.

Truth to tell, I have concluded these are overkill and not really needed. My later Euro Super sedans have a breather pipe directly back to the air filter housing and there is NEVER any oil in the air cleaner body or stain on the filter element. Perhaps that is a sign of a well running good engine, but I have had several Supers like this, 1600-2L. The breathers on the earlier models, 66-68 with the crossover filter pipes, also piped it directly into the intake plenum and I've had no oil in those areas also. perhaps is a highly worn engine spewing oil, or perhaps needed to pass air cert tests.
 

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Also they get rusted out in which case you need a replacement. The OP said his was shot so a replacement was probably his only option.

I recently used my ultrasonic cleaner on the OVS off of one of my 164's (same device with minor configuration differences) and although I had soaked it for a week in solvent and flushed it out thoroughly I still got a lot of crud out of it (flakey hard bits the color of rust) Problem is my ultrasonic cleaner is too small so I can only submerge half of the OVS at a time but I'm thinking of getting the larger one. You can never have too many tools.

BTW yes, the OVS is essentially an emissions device. It's an elaborate PCV.
 

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I'm one of those yoyo's

Here's what the corrugated bit looks like. It is 2 sheets. One flat and the 2nd is wavy. They sit against one another and it's rolled up for more surface area. Even after 26 years, this one is very flexible still. I cut this one apart lower down the body than usual and the dern thing unraveled on me. I don't advocate cutting it so low. When I cut the others apart, I did so up near the top and the media remained rolled and fastened as it should be. Learn by doing eh?

My 89 4 banger 75 doesn't have one. My 89 4 banger 164 does. If I ever come to the point where I cant get one to cut up and clean I'd bypass it with a tube and catch can like the one I got for the 75 from Alfaholics - tho I've not installed it yet. I do know, if it's clogged up it does affect the running of the engine. The other misc pics show some of the gook that came out of one I DO clean regularly. I've cut a bunch of these apart and have never encountered a brass media that has disintegrated or broken apart. I think the crud that comes out of these confuses some of us - used to be me as well - that the media is degrading. I do know it is very important that the drain back line be kept clear. I change mine every year just cause it's a foot of vacuum line and 5 minutes time.

I like Mr Pauls ultrasonic method thinking. If I could source a small 220 volt unit, I'd do it the same way in future. The machines are quite expensive here. Ciao, chris
 

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actually the drainback line (apart from having to be clean), be it to the dipstick or to the block, depending on year, has to have about 20cc oil in it. This acts a bit like water sitting in the U-bend under the sink.....it prevents crankcase fumes going back into the OVS that (probably) help to rot it out.
 

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I've heard that theory before however the drain on the 164's is a straight vertical shot so I'm not convinced of it's validity. On my '72 Spider it's a long shot across the bottom of the radiator to the dipstick so by nature it's going to have standing oil in it but I honestly don't see how that affects the operation.

I know there are people who have ditched the thing completely and just gone to an open breather with a catch-can but if you keep them clean with periodic maintenance they are a pretty neat device. The problem is many already have 30 or 40 years of deferred maintenance on the books and in fact have never been cleaned.
 

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I shall try

I like your blog!!

OK, these first 2 pictures are different OVS. The first one is the 1st one I cut open. I did so just below the seam on the very top. It's the one in the thread I did last year. I gave consideration to this and was going to clip it like a dizzy cap but the way it mounts to my engine precluded that. So I used that stuff we know as F4 tape. It's self vulcanizing silicone tape. In the pic, you can see the tape. There is no pressure in system so it works well. Just make sure you know the orientation of the top half to the bottom half. Scribe a line or paint some dots on the upper and lower bits. I used a silicone sealing ring from an espresso machine to add to the airtightness of the OVS. It's working very well on the car. I'm sure it is just me but it seems to be running "purer" but that could be from clearing all the oil residue out of the lines to the intake as we do every year.

Here is a link to the original "wonder what's in here" thread:

http://www.alfabb.com/bb/forums/164-168-1991-1995/300753-oil-vapor-seperator.html

The second one I cut lower down as the bracketry that holds it to the plenum will go right over the seam. Sealed with same tape then the rubber insulator slips over it all. I highly recommend cutting one open higher up the body of the OVS as cutting lower released the brass ribbon and putting it back together was very fiddly. Cutting it higher precluded ribbon coming apart. The bell cone does fit snug over the rolled up ribbon so this helps keep things secure. My gut is "if it wouldn't leak, prolly could run it just pressure fitted together" but we all know better.

The lowest picture is how it looks mounted. This OVS had not been cut apart - yet. You can see the clearance issues and the center rubber isolator/bracket. kcab suggested the F4 tape and it does work well. Looked on amazon and indeed a - what looks to be - nice ultrasonic cleaner 220V is about 100 bucks!! Hmmmmm ciao,
chris
 

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The water pump bypass hose off of some for 3.0L Ford/Taurus motors are a close fit. I have had no, none, zero luck in sourcing for this and the other 2 "big hoses". My next hidey hole to look in will be a silicone tubing supplier. It would be fairly straightforward if the metal ends were the same size. If no joy in this approach, I may look toward Earls or Russells for a solution tho I'm not too concerned about originality where you might be. Ciao, chris
 

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Classic Alfa sells some of the hoses for injected engines. Maybe they could be adapted to fit? Part numbers EN133 and EN134.
 
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