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Discussion Starter · #1 ·
Hi everyone, I'm new to the Saab community. Just got an 03 aero and have been battling the oil pressure light at hot idle. Been all over the forums and google searching for a cause, and i haven't found someone with a solution. I've seen people clean pickups, change bearings, oil pumps, covers, pressure valves, thermostats...... And still that damn light at idle. In my particular case as soon as the car reaches temperature the light comes on idle 600rpm. A soon as i touch the gas ( 800 rpm ) light is off.
I'm in the middle of rebuilding a 2001 b235e ( which is my other dilema, what is really b235r on a b235e ). But im afraid of starting a rebuilt motor with this oil situation still unresolved. Has anybody successfully sorted this out? I ran into a thread about the balance shaft being replaced and problem solved, but it just doesn't make sense to me.
Plus i think there should be a comprehensive thread stocked on this subject
 

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If your building a new engine that will replace everything that would cause this engine to have low oil pressure. Your oiling system is all internal and a drop of oil pressure at idle could be many things as you have discovered. There is never one real reason for your situation. It could be one of many or several. For instance... As your bearings wear there becomes more of a gap between the bearing surface and the journal. As that gap widens it takes more oil to fill the gap. This also makes it easyer for the oil to escape, causing les back pressure, AKA oil pressure. This can be caused by one realt bad bearing that you would most likely hear or several or all your bearings being slightly warn. The reason your oil pressure light would go away at higher revs is because oil pumps make a surplus of pressure/flow because as the engine revs it requires exponentially more lubrication.

But to be honest that's just pressure loss dew to bearing wear. It could be the pump it's self or sludge buildup. Just keep on with your engine build and keep and pull your pan and clean things out in the meantime.
 

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If you are getting only 600 rpm at idle that is likely the issue. Normal 9 5 idle speed is 850. I believe any unit idling at 600 rpm will get a light just because it is too low and not because there is something wrong with the motor.
 

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If you haven't dropped the sump, and upgraded to the PCV 6 there's no point in trying to guess what it could be; but by the time we run out of guesses you will need that lower power 235e. How many miles is on the car? What oil do you use? Pull the VC and see what the engine looks like top side. Do you have any oil leaks/loss?

Hi everyone, I'm new to the Saab community. Just got an 03 aero and have been battling the oil pressure light at hot idle. Been all over the forums and google searching for a cause, and i haven't found someone with a solution. I've seen people clean pickups, change bearings, oil pumps, covers, pressure valves, thermostats...... And still that damn light at idle. In my particular case as soon as the car reaches temperature the light comes on idle 600rpm. A soon as i touch the gas ( 800 rpm ) light is off.
I'm in the middle of rebuilding a 2001 b235e ( which is my other dilema, what is really b235r on a b235e ). The difference is horspower.
But im afraid of starting a rebuilt motor with this oil situation still unresolved. Has anybody successfully sorted this out? I ran into a thread about the balance shaft being replaced and problem solved, but it just doesn't make sense to me.
Plus i think there should be a comprehensive thread stocked on this subject
 

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Discussion Starter · #6 · (Edited)
Dropped the pan first. Clogged as usual....
Dropped main and rod bearings , some worn as usual replaced.
20w50 lof ...
New sensor
pcv 6 done previously
Pulled oil thermostat thinking maybe clogged oil cooler.
Car is not knocking or anything , no.smoke , no noises.
 

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Discussion Starter · #7 ·
If you are getting only 600 rpm at idle that is likely the issue. Normal 9 5 idle speed is 850. I believe any unit idling at 600 rpm will get a light just because it is too low and not because there is something wrong with the motor.
i still cant see why 500rpm would cause low oil pressure...
ive usually had bmws, and on a stick shift bmw , i can bring the idle to 200rpm by holding the brakes and slowing the engine down with the clutch... and still have sufficient oil pressure.
not saying that its a possibility but it doesnt seem normal. even a vacuum leak can bring the idle down to 500-600.
 

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Your oil is to thick and your Oil Pump is probably working to hard at idle; change to a thinner oil eg: 5 or 10w. What type of driving do you do?


Dropped the pan first. Clogged as usual....
Dropped main and rod bearings , some worn as usual replaced.
20w50 lof ...
New sensor
Pulled oil thermostat thinking maybe clogged oil cooler.
Car is not knocking or anything , no.smoke , no noises.
 

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Discussion Starter · #9 ·
If you haven't dropped the sump, and upgraded to the PCV 6 there's no point in trying to guess what it could be; but by the time we run out of guesses you will need that lower power 235e. How many miles is on the car? What oil do you use? Pull the VC and see what the engine looks like top side. Do you have any oil leaks/loss?

this alone is probably worth starting a new thread, but why would a b235e result in lower power? from my findings the long block is identical except for:

the trapezoidal ends on the rods, pistons different material , exhaust valves and exhaust cams (which i will probably all reuse from my b235r if they are still good)
from my understanding the power output difference lies in the turbo and software.
can someone please verify this ?
 

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Different engine configurations; for Aero and other 2.3L models; some engine parts will fit some won't.


this alone is probably worth starting a new thread, but why would a b235e result in lower power? from my findings the long block is identical except for:

the trapezoidal ends on the rods, pistons different material , exhaust valves and exhaust cams (which i will probably all reuse from my b235r if they are still good)
from my understanding the power output difference lies in the turbo and software.
can someone please verify this ?
 

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I second the thought that your idle is a bit low, my car when warmed up idles at just over 800rpm. I have the Torque app for my phone and a bluetooth adapter to check this precisely and thata number has not changed in the 4 months I've been running this on my phone.
 

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On the 4cyl; as low as 750, engine warm is acceptable; with the torque mine is around 824 warm.


I second the thought that your idle is a bit low, my car when warmed up idles at just over 800rpm. I have the Torque app for my phone and a bluetooth adapter to check this precisely and thata number has not changed in the 4 months I've been running this on my phone.
 

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Discussion Starter · #17 ·
Im not disagreeing with the fact that my idle is low . In fact I'm pretty sure that it is tired to my oil light because as soon as i touch the gas oil pressure goes up. Im more surprised that a 600 idle would cause a low oil pressure scenario. This would mean that under normal circumstances if you would have a vacuum leak our a dirty throttle body you would be under risk of smoking a motor?
 

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Discussion Starter · #19 ·
It was aftermarket.... Ive ran into a post mentioning the aftermarket switch problem.. However i am in the middle of installing am oil pressure gauge just to verify everything.
 

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Discussion Starter · #20 ·
Definitely not the switch, between running around with the pressure gauge hooked up. Cold i get very good pressure ( 20-15), warm starts to drop all the way down to 5.
 
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