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Discussion Starter · #1 ·
Has anyone tried this with their pickup screen?

www.saabservices.com said:
Prevent SAAB 4 cylinder engine failures.

SAAB 900, 9000, 9-3, and 9-5 can all benefit from this modification.

One solution for SAAB oil pickup screen becoming clogged with sludge and/or oxidation product particles.



We are not the first to use this method, but we felt that an engineering explanation of the method was in order. The author of this document (blue text) is D.O. Schultz.

Mr. Schultz is a retired engineer, pilot, and FAA licensed airframe and powerplant mechanic, and has driven Saabs for many years. Currently he owns a 9-5 wagon.

The existing wire mesh screen has an open area on the pickup of 62mm diameter, which equals 4.67 sq. inches of area.

This particular screen, called 30 mesh, is manufactured .011” diameter wire, spaced .033” on centers, in a square pattern. Openings are .022” X.022” and .031” on the diagonal. This equals an open area of 40.8 % or 1.91 sq in which is about 410% of the pickup tube ID area.



Replacement screen vs original. Placing a strong magnet on the back of the pickup is advised.

The proposed replacement screen is based on proven history in the Continental TSIO-360; a 220 hp turbocharged, intercooled aircraft engine that has been is use for over 30 years. In this application, there is only 1.1 sq in of total screen area and the perforations are .081”diameter, resulting in an open area of .385 sq in. Normally this screen remains clean at oil change intervals of 50 hours (which equates to about 3,000 miles of highway driving) unless there is an internal part failure in the engine.



Using this historical example, the screen shown is made from 22 gauge mild steel using .079” diameter perforations, staggered on 7/64” spacing.

This equates to an open area in the modified SAAB pickup, when directly replacing the wire screen, of 46% or 2.15 sq inches, which is 474 % of the pickup tube ID area.



The factory screen allowed passage of a particle of up to .022” and the replacement screen allows passage of particles up to .079” diameter.

This equates to a 260% increase in particle size and a 12.5% larger open area for less overall screen restriction.

Careful examination of the ”sludge” reveals that it is primarily composed of small granules of what appears to be cooked oil and is not a hard substance like combustion chamber carbon particles. These granules should not cause any harm to the oil pump and will be trapped in the full flow oil filter and thus not continue to circulate in the oil system or serve as a clogging agent for the pickup screen.

It goes without saying that the oil filter must be changed at each oil change and in our opinion this period should not exceed 3 to 5,000 miles or every 90 to 180 days.

 

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Never tried that, no.

But, mine does have a hole the size of a pencil punched in it. :cheesy:
 

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It sounds like a good idea, since the screen is designed over caustiously. My only questions is why bump up so high (I'm thinking availability and price)? Other screen sizes like 10 screen material might be just fine.

I would only question one statement b/c i'm not a pump guy "Careful examination of the ”sludge” reveals that it is primarily composed of small granules of what appears to be cooked oil and is not a hard substance like combustion chamber carbon particles. These granules should not cause any harm to the oil pump and will be trapped in the full flow oil filter and thus not continue to circulate in the oil system or serve as a clogging agent for the pickup screen."

I would think sludge could then build up in the in the oil pump walls, much like it does in the engine and crankcase. This would probably take much longer than a clogged pickup screen, so probably not a big deal.

I would also like to know what magnet he mounted behind his new screen and how he mounted it.
 

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Bad idea!!! Don't do that. I saw this method a long time ago. Basically the carbon particles you see on the screen aren't carbon, they're plastic shavings from the timing chain cover, plastic guides and the degraded remains of the PCV valve hoses insides (have you seen one disected? Not a pretty sight)

Any how, poking the holes, small as they may be, will let those particle go into the oil pump gears and sometimes lead to failure over time. The best thing is to either drop the oil pan from time to time if sludge is discovered or to buy one of those pans with a sludge inspection access
http://www.saabnet.com/tsn/class/parts.html#070611abcsa
 

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tucksayre said:
It sounds like a good idea, since the screen is designed over caustiously. My only questions is why bump up so high (I'm thinking availability and price)? Other screen sizes like 10 screen material might be just fine.

I would only question one statement b/c i'm not a pump guy "Careful examination of the ”sludge” reveals that it is primarily composed of small granules of what appears to be cooked oil and is not a hard substance like combustion chamber carbon particles. These granules should not cause any harm to the oil pump and will be trapped in the full flow oil filter and thus not continue to circulate in the oil system or serve as a clogging agent for the pickup screen."

I would think sludge could then build up in the in the oil pump walls, much like it does in the engine and crankcase. This would probably take much longer than a clogged pickup screen, so probably not a big deal.

I would also like to know what magnet he mounted behind his new screen and how he mounted it.
Have you seen a SAAB oil pump removed from the engine? It is a gear pump, meaning there are two gears meshing. That will rub off anything that might try to get deposited on the pump itself.

Not to mention, most things with oil flowing through them don't sludge, it's where oil pools and cools where sludge forms. (Heads and sumps)
 

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The c900 ran with a bigger mesh for it's lifetime on essentialy the same engine without problems. Plastic and rubber debris will just get squashed and ground up in the metal teeth of the pump - I'd rather have a good flow of oil and accept the occasional but of soft gunk going through the pump.
 

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Discussion Starter · #7 ·
hkayssi said:
Bad idea!!! Don't do that. I saw this method a long time ago. Basically the carbon particles you see on the screen aren't carbon, they're plastic shavings from the timing chain cover, plastic guides and the degraded remains of the PCV valve hoses insides (have you seen one disected? Not a pretty sight)

Any how, poking the holes, small as they may be, will let those particle go into the oil pump gears and sometimes lead to failure over time. The best thing is to either drop the oil pan from time to time if sludge is discovered or to buy one of those pans with a sludge inspection access
http://www.saabnet.com/tsn/class/parts.html#070611abcsa
I hear what you're saying but I think the point here is that the Saab has a much finer mesh than most cars. While I agree with you about the rubber from the deteriorating hoses I don't think it would harm the hardened oil pump gears. As for plastic breaking off of the timing chain guides, this should only happen when the oil screen has already clogged, starved the timing chain of oil and allowed the chain to become so slack that it is beating the guides and breaking them. On my car, when I pulled the guides they were perfectly intact and showed no signs of wear. I did have some plastic from the balance chain tensioner but I broke that when I tried to remove it and it jammed.

The c900 ran with a bigger mesh for it's lifetime on essentialy the same engine without problems. Plastic and rubber debris will just get squashed and ground up in the metal teeth of the pump - I'd rather have a good flow of oil and accept the occasional but of soft gunk going through the pump.
I agree with you here. On that site they showed a car with a screen 50% clogged after 16k miles.
 

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Strap a magnet to the outside of your oil filter if you are worried about ferrous material in your oil.
 

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If you feel that strongly that the mesh used is too fine, use the poking holes in the mesh screen method; basically poke 4-5 very small holes in the mesh screen thus preventing the small sludge particles from accumulating too much but not letting out any of the bigger sized stuff.


This is what the PCV system might look on the inside when it's deteriorated
http://www.flickr.com/photos/[email protected]/sets/1730928/
 

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Gripen 1985 has reported that he has learned that the 9-3 that he has owned for the past 4 years has all this time had a screen that someone had poked a large hole in more than 4 years ago-as a cheap and dirty 'fix' for a blocked screen. This seems to indicate that the 9-3 could tolerate a screen that has larger openings than the original equipment.
 

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john bernard said:
Gripen 1985 has reported that he has learned that the 9-3 that he has owned for the past 4 years has all this time had a screen that someone had poked a large hole in more than 4 years ago-as a cheap and dirty 'fix' for a blocked screen. This seems to indicate that the 9-3 could tolerate a screen that has larger openings than the original equipment.
you should never have a large hole poked in the screen :eek: . Even the small hole method isn't very recommended, however, when a sludge problem is detected, the extra slightly larger holes in the screen allow for less blockage when remaining sludge finds it's way to the sump thus clogging the screen. the small holes would allow for the amall particles to go past the screen but the larger diameter particles remain on the mesh screen. In some cases, the particles that go past the screen could damage the oil pump
 
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