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74 Spider 78 Spider 84 Spider
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Discussion Starter #1
The small hose that returns oil to the base of the dipstick....Is that gravity drain or is that sucking oil back by vacuum? I gather that there is a continuous vacuum going thru this hose sucking whatever oil drips the OVS is scavenging.

I ask because my return line is routed in a way that it is higher than the OVS in a spot. It's difficult to get it to have a continuous slope to the dipstick. And where is goes along the bottom of the radiator support it seems lower than the dipstick anyway, making a P-trap.
 

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The original configuration that runs the hose below the radiator is effectively lower than the connexion at the dipstick tube. There are instructions to inject a few ml of oil in the hose when you reinstall it, effectively making it into a p-trap. This is supposed to prevent crankcase fumes from escaping.
 

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Discussion Starter #4
I'll have to investigate with my vacuum gauge. I assumed a slight vacuum would draw separated oil back to the sump...perhaps not and thus hose routing is critical.
 

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Discussion Starter #6
test results...pulled the return line off the OVS and plugged the drain nipple. Inserted vacuum gauge to the return line....NO vacuum, NO pressure...reved the engine a bit and no movement on the gauge...well maybe a 0.1% needle movement. Basically nothing measurable. Or is my brand new hose clogged already? Or is the dipstick fitting clogged?

It seems there is nothing but gravity that will return oil to the sump. Which might explain why that line gets clogged so often. There is no oil flow unless fresh oil is coming from the OVS to push the old oil at the bottom of the hose into the sump fitting at the dipstick. I'm guessing the oil recovery by the OVS is really just a constant slow "drip" that works it's way down the hose and eventually to the sump. But it's so slow that if not driven on a regular basis, can become stagnant and develop into a clog?
 

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Does anyone know what size line this is? thinking it will be easier to just replace it for $20 than to mess around trying to clean it! Thanks!
 

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Does anyone know what size line this is? thinking it will be easier to just replace it for $20 than to mess around trying to clean it! Thanks!
.Doesn't your go to the sump right below the OVS? . that is just the tip of the iceberg.. It clogs from a malfunctioning ROTTING .. no other way to put it ..OVS internally.. I see you are a new poster so you have some catching up to do. As for priming the line .. ( it will fill-up with debris again in short order) .

Search up on this forum and all the "OVS" threads.. some are long and wordy so pour a cup of coffee and start click ing and scrolling. To search ..click the THREE DOTS next to you avatar ..upper right hand corner and go to advanced search Then OVS Oil Vapor Separators in Key words and my handle in members .. Click this to open A Permanent Solution to FAILED CORRODING Oil Vapor...
 

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.. that is just the tip of the iceberg.. It clogs from a malfunctioning ROTTING .. no other way to put it ..OVS internally.. I see you are a new poster so you have some catching up to do. As for priming the line .. ( it will fill-up with debris again in short order) .

Search up on this forum and all the "OVS" threads.. some are long and wordy so pour a cup of coffee and start click ing and scrolling. To search ..click the THREE DOTS next to you avatar ..upper right hand corner and go to advanced search Then OVS Oil Vapor Separators in Key words and my handle in members .. Click this to open A Permanent Solution to FAILED CORRODING Oil Vapor...
Thanks divotandtralee! Yeah I have been doing a lot of reading...this is such a great site to learn from, though it can get a bit overwhelming for a newbie like myself with so many opinions about any given subject! Since new OVS's are not available I was going to do my best to clean the one I have and replace the lines to and from it. Waiting for Centerline to deliver a new crop of OVS's! Thanks again!
 

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Thanks divotandtralee! Yeah I have been doing a lot of reading...this is such a great site to learn from, though it can get a bit overwhelming for a newbie like myself with so many opinions about any given subject! Since new OVS's are not available I was going to do my best to clean the one I have and replace the lines to and from it. Waiting for Centerline to deliver a new crop of OVS's! Thanks again!
John, CL has been back ordered for years and forced me to engineer a copy of the OEM OVS in BRASS. I sell the kit in the thread for $120 shipped.. Cleaning yours is a total waste of time and energy and solvents and whatever. I build the kit MYSELF and have sold over 100 since last July when I introduced them. Mine is the only game in town. Yves ..poster #2 is a good customer!
 

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I can vouch for divotandtralee’s kit. Very well designed and the instructions make assembly pretty easy if you’re comfortable with soldering. It will never rot.

Regarding the return line, I don’t recall the size but it’s metric and available by the foot/meter. I think I got mine in silicone.
 

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I enjoyed putting it together, it's actually a work of art.

The oil return line on mine was plugged. A combination of solvent, steel wire and compressed air blew out a blob of rust flakes that was trapped near the bracket that holds the line on the corner of the rad. This rust is what a decaying separator returns to your oil pan. Enough said.

BTW a vinyl tube should do it, $2 should be enough.
 

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I enjoyed putting it together, it's actually a work of art.

The oil return line on mine was plugged. A combination of solvent, steel wire and compressed air blew out a blob of rust flakes that was trapped near the bracket that holds the line on the corner of the rad. This rust is what a decaying separator returns to your oil pan. Enough said.

BTW a vinyl tube should do it, $2 should be enough.
Ordered mine today! Looking forward to a better running car and less fumes in the cabin!
 

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I used the method Yves did .. and describe it in the instructions.. It's a mini-Roto-Rooter operation and a lot simpler than replacing the line which is in an awkward place, strung under the radiator especially if you have a sump guard.. Just double over the wire tip so it doesn't get hung up as it is finding its way through the restriction of the rust blob.It clears out with a little persistence and patience and a final flush with Bakekleen... Pretty amazing how much gunk is in there. What is really surprising is Alfa never had a service schedule on these matters which falsely lends to the perception it is good for 40+ years. The other item is the skinny metal pipe return to the cam cover outlet that runs along the top of the manifold. It is a return line from the gas tank to recycle gasoline fumes from the tank (SPICA).. I think the current Porsche doctrine on their modern cars is to toss their OVS on a regular schedule and replace it periodically.. There are some interesting videos on it on You tube explaining why.
 

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Great advice! Will try the roto rooter method. I’m guessing this will help my spider rum more smoothly and perhaps even a little more pickup?
 
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