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Discussion Starter #1 (Edited)
Oil pan and oil screen cleaning, bearing inspection

1996 SET, 107k miles and counting... Belated 100k overhaul in progress. Finally got as far as the oil sump and the oil screen.

As expected, the screen was about 80% plugged, which was probably the root cause of the worn chains and chain guides. Fortunately, I had decided not to do this job myself, because we also found a handful of metal flakes in the screen and sump. The mechanic pulled one each of the main and rod bearings. Rod bearings are shot as well.

List of worn or damaged parts now includes timing chain, balance chain, chain guides, probably the balance chain tensioner, and rod bearings.

Pics show the open oil sump, closeup of the screen, and half of a rod bearing.

Link to more oil pan pics and details:
http://www.geocities.com/ng900set/Oilpan/oilpan.html

Link to related post on the rod and engine bearings:
http://www.saabcentral.com/forums/showthread.php?t=53285
 

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Do you have any of the oil change history ?

Did the hydraulic lifters continue to function, or did that go "click - click !!" or tick - tick ??

The chain does stretch, then the guides are worn down - I do not see the oil having much of an effect on this..
 

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Discussion Starter #3
earthworm said:
Do you have any of the oil change history ?
I have owned the car since new, so I pretty much know how it has been driven (lots of short trips for 3-4 years of its life), and how the oil was changed (often).

Did the hydraulic lifters continue to function, or did that go "click - click !!" or tick - tick ??
A few months ago, there was a problem with one leaky intake valve. Fixed after a couple tanks with valve-clean.

The chain does stretch, then the guides are worn down - I do not see the oil having much of an effect on this..
Not sure about this myself, possibly not enough oil flow to lubricate the chains and guides well, some oil passage may have clogged. May or may not be related.
 

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Discussion Starter #5
Ice Man said:
What kind of oil did you use?
Conventional oil, 3-5k between oil changes, 3-4x per year. If you are wondering whether one can prevent the same thing from happening by using synthetic oil, or changing oil even more often, I don't know. Even though it gets more attention now because newer 9-3 models appear more susceptible than the older 900, I suspect the 9-3 may be getting a bad rap there.

People who actually fix these cars for a living seem to be looking at other things, like short v. long trips, low winter temps in combination with emission requirements (poor crank case ventilation) etc. A shop that deals primarily with German imports saw an almost completely clogged engine on an Audi after 27k miles. I don't think the answer will be found on a message board.

A better question is how to detect it before the chains and bearings are worn, or worse, before the engine breaks like many are doing. From the statistics, it seems most people have no warning. If you can detect it, running the sump and oil screen through a parts washer is a cheap fix compared to the alternative.
 

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Whooooo:eek:

Now that makes me want to strip the sump of my 94 900t at its current 83000 miles and clean the screen.

I know its quits a job. What with the subframe off ect but maybe its worth it??

Dead
 

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You have done all correctly, PMI. More than I can say for myself, but I do avoid those short trips - she either sits or runs..

I believe much automotive engineering is shared, maybe all the auto-makers use the same screen grid ???

And there is a strong possibility that the stringent emissions controls has something to do with this..

In the 30s to 60s, the engines did run cooler, but then the emission-controls were nigh zero and the oil change interval was one to two thousand miles as I recall.

Volkswagen was at 1,500 miles with a cleanable screen..

And maybe these "modern" cars should be the same way.
GM does have ( or did have) one engine with the filter directly in the sump, but I do not know how this affects the screen..
 

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With 113K miles on my engine now I'm definitely going to start looking at taking the sump off, maybe run some Seafoam through the system.
 

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Discussion Starter #9 (Edited)
Description of how the oil sump was removed, with car on the lift:

The air shields we already off.
Oil was drained.
The plastic crankshaft pulley access cover was removed.
Passenger side subframe bolts were removed in the front with an air tool, but the subframe was left attached in the back.
Exhaust was separated between the cat and the flex pipe, and left hanging.
O2 sensors were unscrewed to protect the wires.
Sump bolts were taken out with an air tool.
Couple whacks on the side of the sump with a soft mallet and it came loose.
A pry bar was inserted between the loose end of the subframe, and the front crossmember. One person held the subframe section down about two inches with a pry bar from the front while another one worked to get the oilpan out. Then the sump was moved toward the exhaust side, and rotated 90 degrees, and it came out.

The metal plate over the screen was removed, then the screen. The metal flakes and bits were under the metal plate, in and around the screen. I did not see any earlier when I drained and strained the old oil through a cloth. It does not look like you could get anything out of the sump fishing around through the drain hole with a piece of wire. That may work on other cars, but I don't see how it could work here.
 

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Discussion Starter #10 (Edited)
earthworm said:
In the 30s to 60s, the engines did run cooler, but then the emission-controls were nigh zero and the oil change interval was one to two thousand miles as I recall...
Some models have a heat shield between the sump and the exhaust, attached to the sump. My car did not have one... may not mean much, not sure.

As for an engine flush, I had already used Amsoil Engine Flush once, and Auto-Rx once. Those may help clean some parts of the engine, but not really intended to clean clogged oil screens, not when they get like this.
 
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