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Loss of oil in Saab 9000 CSE Turbo

I have a 1997 Saab 9000 CSE Turbo. It has been a great car overall. Last summer, our water pump died while cruising on the highway, leading to a major overheat, leading to warped head. We decided to roll the dice on a rebuild, which was done by a reputable import specialty shop that has worked on many Saab 9000s. Since we got the car back 5000 miles ago, we have lost a few miles per gallon, and we hear a rough noise in the engine (particularly when it’s cold). In the last few thousand miles, we lost a lot of coolant, apparently because the new water pump is faulty (the shop looked at it and agreed to replace under warranty). In the last 1000 miles (but no evidence of it previously), we have begun losing oil like crazy and occasionally (but not most of the time) smelling burning oil (the heater is on, moving air around). We are now adding about a quart per 200 miles. When we inspect the block, there is some small evidence of oil leakage, but not a lot, and there are never drips on the driveway.

Where is all that oil going? I showed it to the shop, we put it on the lift, and there is no spray on the underside, leaking oil pan, etc. I suspect the new head gasket is leaking, but there is little enough residue on the block that it’s hard to be certain. What other explanations are there, and is it fair for me to blame the repair shop and insist that they redo the head gasket? The shop is a 6hr drive from my house, so I can’t just drop by to discuss it with them.

Thanks for your advice!

This is indeed a puzzle. Well, the oil has to be going somewhere. Maybe it is only leaking while you drive. In that case, it would be leaking from a part that is presurized, like the oil pressure sensor, the front or rear main seal. I think you would spy signs if there was a big oil leak from the top part of the engine, so I doubt it is the valve cover gasket or the cam seal or the head gasket exterior leak. Ask your mechanic to look in the area of the oil pressure sensor and the two main seals while the car is idling and being rev’d a bit. Maybe the leak will be evident then.

More likely the oil is either leaking through the head gasket into the coolant jacket, and getting into the radiator fluid. Or it is just blowing past the piston rings and being burned and out the tailpipe. Take off the radiator cap and look at the radiator fluid. Does it have an oily film on top? Look at the end of the tailpipe. Does it look and feel oily and greasy?

It’s hard to say who or what is to blame at this point.

When you overheat a turbo engine there’s a good chance the turbo bearings will be damaged. Not only does oil circulate thru the turbo to keep it cool, but coolant also passes thru the turbo to keep it cool.

Have you pulled the oil dipstick out to check the condition of the oil?

Tester

What was done on the rebuild? Complete top and bottom? Valve guides and stem seals for the heads. Journals, end bearings, pistons, rings, block rebore( or sleeves, I forget) and the rest of the banana? Block should have been scoped for cracks. If the job was sub $3K you may have gotten less than you needed.
Lastly was the turbo checked for an oil leak? Some turbo bearings were famous for blowing a lot of fine oil mist. This could be checked with a hydrocarbon emission test while running. Burning a fine hot oil mist while in turbo mode may not leave a lot of oil deposits or detectable smoke and will ding your fuel economy.

Overheating an engine quite often leads to piston ring damage and this can be a major contributor to oi loss. Rings can seize in their ring lands (grooves) or lose their temper; which means loss of springiness and that in turn means a poor fit in the cylinders.

Replacing a head gasket only (which I assume is the case here) can be a dicy proposition if a dry and wet compression test was not performed before the head is removed.

At this point I would go back and have both the dry and wet compression tests performed. Good cylinder readings should be in the 175 PSI and up range. If the readings are lower (say 130, 140, etc) and they go up dramatically during a wet test then the rings are shot.
This means you would need another engine and is a good reason why a repair like this should not be done without some diligence in advance and even more so if the engine has high miles on it.

At 200 miles per quart the converters and O2 sensors are probably not going to last over the long haul either.

I second the compression test. That will tell you if you are loosing oil past the cylinder rings.

As others have mentioned, the oil seals inside the turbo are also a common source of oil loss.

However, the fundamental fact is that the oil has to be going somewhere, and if it’s not going on the ground, then it must be going out the tail pipe. If you are having to add oil every 200 miles, there has to be some pretty obvious evidence of where the oil is going somewhere. Are you noticing any bluish smoke coming out the back? Is there carbon build up (soot) around the tail pipe?

I’m assuming they either replaced the head or shaved it to obtain the correct flatness, right? Did they also pressure check it, and inspect for cracks?

Check the oil and the coolant overflow tank. If either one looks like creamy mayonnaise or a milkshake, then you have oil and water mixing, most likely due to a failed head gasket, or a crack in the head.

How many miles are on the car? Do you know when the last time the turbo was replaced? The T25 turbos in the 9000 CS/CSE’s typically last in the 125-150k miles range before they need rebuilding. Try pulling the big elbow shaped hose off of the throttle body, is there a lot of oil collected in there? It’s common to have a few milliliters of oil collected in there, but if the inside it rather thickly coated, then that indicates a problem. You can also pull the big hose down by the cooling fan that goes into the turbo. Again, it’s ok to have a small amount of oil, but a serious coating isn’t good. If you do this, also try to spin the turbine blades with your fingers. They should turn easily, and not wobble (do all of this when the engine has sufficiently cooled off, of course).