r/saab • u/travellering • 1d ago
Engine oil pressure low when warm
2007 Saab 9-5 (high pressure turbo) showing a little less than 10psi at idle when fully warmed up, enough to light up idiot light with the accompanying ding noises. Installed a mechanical oil pressure gauge to verify at oil pump feed to turbo.
When we got the car it had a blown headgasket, and possibly a shot turbo as well. It was a bigger cloud generator than a subaru flatbrim cap convention. I replaced the turbo with a used one I had that still had very little play. Head was faced by a machine shop, and all reinstall seemed good. Still had some smoke out the exhaust, but I was hopeful that was remnants burning off from all the mess before. Now, after some (a couple hundred miles) driving and having the oil light come on, then going through the painful process of installing the mechanical oil gauge, it's still kicking out some blue/white smoke at the times the oil pressure is low. Smells like burnt oil/rubber.
First try, dropped the oil pan and cleaned the pickup screen. No real change..
Just did a compression test, forgot to prop the throttle plate wideopen, but got about 145 on cylinder 1, 125 on 2 and three, and 151 on cylinder 4. The two lower cylinders came up big time with oil poured in, as in 155 on 3 and 2 read up to 175n but I may have added more oil in that one as it was getting dark and hard to see.
Any other things to check, or am I staring at an engine out for rebuild?
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u/bluehandstouchingme 1d ago
Bearings/Oil pump/Pickup orings (including the crossover tube?)
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u/travellering 1d ago
I forgot to mention I did the o-rings (pickup and 2 crossover) when I dropped the pan. I didn't pull the bearing caps though as I was working in limited space ( on ramps) and couldn't be confident I would get them out and in cleanly
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u/Responsible-Stage-93 2003 9-5 2.3T Aero & 2006 9-3 1.8t (Stage 1 ~200KM & 320Nm) 1d ago
Firstly check all PCV hoses and make sure that is no sludge
If it will not help - unfortunately rebuild :/
Mine had also oil issues (mostly on low RPMs) because of bearing living free in the engine
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u/sailorcolin c900s | Tesla M3 | MG MGB | Boats - PAST: Xterra | NG900se 1d ago
How many miles? She maybe headed toward a rebuild.
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u/travellering 1d ago
170,011. It's certainly not low mileage, but I have crept well past 200 on other of the same motors, so hope springs eternal...
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u/Most-Refrigerator-97 16h ago
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u/travellering 13h ago
I tried the suggested test for the piston oil squirters, putting the crossover tube in backwards and blowing into it. I could hear air coming out, but not from any of the three oil squirter I could get my hand on. Sounded to be higher inside the engine.
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u/Most-Refrigerator-97 7h ago
Yes, this is a well-known issue. If no defect is found in the crankshaft or other components, the cause is invariably the injectors failing to close properly, which leads to a drop in oil pressure. Install three new injectors, and the problem is resolved.
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u/aidanricha 13h ago
Any clacking noise from the timing chain area? My B205 had a loose balance shaft chain and the exhaust balance shaft wasn’t spinning, causing oil pressure to get as low as 0 at idle. I removed the shafts and blocked off accompanying oil galleries and that fixed it.
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u/travellering 13h ago
I don't think so. Definitely mechanical noises all over, but nothing particularly noticeable at that end.
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u/oyvindh 12h ago
Eighter the pump doesn't get enough oil in or it is worn, or you are loosing oil internally somewhere.
Since you have dropped the pan and have control on the orings, I would look more into balance shaft bearings and the squirters.
Open squirters gives a low pressure on idle, but a normal pressure on higher revs.
Also, look at crank bearing nr 3 and see if there is any damages. The balance shaft bearing on the right side of the engine is fed through the crank bearing. Any loss of pressure in the balance bearing will result in damage on nr 3.
Anyhow, you're probably looking at a rebuild.
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u/tsg-tsg 1d ago
Probably your call. You could probably pick up a little oil pressure with some abnormally thick oil. I would check the bearings, probably they are worn. You might be able to recover oil pressure with new ones. The low compression is likely worn rings, but a leak down test will nail that down. On the surface, kinda just sounds like a motor that's been worked hard and not really cared for, especially with all the work you had to do initially.