Saab turbo smoking on first start up.
Discussion
So it's getting worse. First start up of the day I'm burning oil. Sometimes it's instantly and sometimes it starts after a few minutes. It clears after maybe a quarter of a mile of less. Subsequent start up's are oil free. Car runs well but I'm sure I'm down on boost. Some days it burns no oil on startup but I can't see a pattern.
Piston tops are squeaky clean, no carbon. Plugs are healthy.
I'm thinking a dodgy stem seal or more likely oil leaking past a turbo seal over night that then slowly finds it's way through the intercooler.
I can check for oil in the compressor outlet pipes tomorrow. Is there anything else to look for. Compressions nice and healthy on all cylinders.
Piston tops are squeaky clean, no carbon. Plugs are healthy.
I'm thinking a dodgy stem seal or more likely oil leaking past a turbo seal over night that then slowly finds it's way through the intercooler.
I can check for oil in the compressor outlet pipes tomorrow. Is there anything else to look for. Compressions nice and healthy on all cylinders.
This is really strange. I've replaced the pcv pipework and inspected inside the pipes to/from the turbo, the intercooler and the throttle body. Nothing looks oily in those. I've ran the engine with the pipes disconnected and clean air flows from them even though the exhaust pipe's smoking like a chimney. I've fitted a spare turbo as well. Compression's 14 bar on all cylinders.
The pistons are now slightly coked and the plugs are darkened around the outer casing but a nice colour on the porcelain. The oil is common across all pistons and all plugs so I can only assume is getting into the intake manifold. On the dipstick I can see that I've lost oil.
The other morning there was a small amount of oil on the turbo mounting flange. The turbo hangs under the exhaust header.
For an engine that runs really well I wish I could figure out how the oil's getting into the cylinders.
The pistons are now slightly coked and the plugs are darkened around the outer casing but a nice colour on the porcelain. The oil is common across all pistons and all plugs so I can only assume is getting into the intake manifold. On the dipstick I can see that I've lost oil.
The other morning there was a small amount of oil on the turbo mounting flange. The turbo hangs under the exhaust header.
For an engine that runs really well I wish I could figure out how the oil's getting into the cylinders.
OK, well done, I thought you would have from your first post, just checking.
You mention the PCV & piping but is there/should there be something in the cam cover to keep oil out of the breathed gases?
Is it worth getting a cheapy OCC (and no, I don't mean an American Chopper) just to put in there & try it if you think it is just from the breather?
You mention the PCV & piping but is there/should there be something in the cam cover to keep oil out of the breathed gases?
Is it worth getting a cheapy OCC (and no, I don't mean an American Chopper) just to put in there & try it if you think it is just from the breather?
Edited by E-bmw on Sunday 16th December 20:02
^ Thanks. Cam cover has a baffle plate, I'm pretty sure it does. It still pollutes with all the pipes disconnected but soon I'll remove the cam cover and probably the intake manifold. I may even have to remove the head but after 4'000 miles I'd be surprised to have a fault across all the cylinders. That's the bit I can't get my head around.
Weirdly there is a post almost identical on the turbo mini forum where the guy is getting huge amounts of oil on top of the pistons, all 4 pistons.
And he says the breather system in no way interacts with the intake, so it cannot be from that.
So either there is a major ring seal problem, or it has to be the guides. Although never heard of guides allowing that much oil past.
But as recent headwork was done..maybe the best area to look at ?
And he says the breather system in no way interacts with the intake, so it cannot be from that.
So either there is a major ring seal problem, or it has to be the guides. Although never heard of guides allowing that much oil past.
But as recent headwork was done..maybe the best area to look at ?
Thanks for the replies. The engine was running well but had a coolant leak on the head gasket so I fitted a new head gasket . The head had a slight skim and compression's a tad higher now, at 14 bar. I've probably owned the car for 7 years or more.
The bores were really good when I removed the head and the piston tops were clean. I've since driven 4000 miles and the car runs really well, it 's a joy to drive. I don't see any smoke once it warmed up.
I had considered piston rings but on every cylinder and with good compression? Same for the guides? I've checked for puddling on the crowns and there's no visible oil. I let the car stand 24 hours before checking. The engine's breathing normally when I disconnect the pcv parts.
The only change I'm aware of is I topped up with a 15 weight oil instead of a 10 but I've done that before. To balance things I topped up with a 5/30 yesterday. So I'll see if that changes anything. Could this be significant?
I once ran one of these engines to 400'000 miles and it was still good. This engines on 205'000 miles which is nothing for a B234R Saab. The faults typical of a pcv fault for these engines but removing the pcv and doing experiments didn't seem to change anything.
The bores were really good when I removed the head and the piston tops were clean. I've since driven 4000 miles and the car runs really well, it 's a joy to drive. I don't see any smoke once it warmed up.
I had considered piston rings but on every cylinder and with good compression? Same for the guides? I've checked for puddling on the crowns and there's no visible oil. I let the car stand 24 hours before checking. The engine's breathing normally when I disconnect the pcv parts.
The only change I'm aware of is I topped up with a 15 weight oil instead of a 10 but I've done that before. To balance things I topped up with a 5/30 yesterday. So I'll see if that changes anything. Could this be significant?
I once ran one of these engines to 400'000 miles and it was still good. This engines on 205'000 miles which is nothing for a B234R Saab. The faults typical of a pcv fault for these engines but removing the pcv and doing experiments didn't seem to change anything.
Edited by Boosted LS1 on Monday 17th December 09:18
What exactly do you mean by removing PCV & doing experiments didn't change anything?
That could be indicating your PCV itself as the issue depending what you meant.
eg - Your PCV is a one way valve that should prevent boost pressure entering the engine envelope.
It COULD be possible that the PCV allowing boost pressure in is then dragging oil vapour/mist back into the inlet when the boost drops and the flow reverses.
That could be indicating your PCV itself as the issue depending what you meant.
eg - Your PCV is a one way valve that should prevent boost pressure entering the engine envelope.
It COULD be possible that the PCV allowing boost pressure in is then dragging oil vapour/mist back into the inlet when the boost drops and the flow reverses.
^ I removed the pcv pipe to the plenum and the pipe to the turbo inlet as well as removing them from the cam cover. Basically the engine was breathing to atmosphere but it had no effect on exhaust smoke .
I've since fitted a new pcv valve, obviously the correct way round :-) I've some miles to drive over the next few days so shall update my findings. Thanks.
I've since fitted a new pcv valve, obviously the correct way round :-) I've some miles to drive over the next few days so shall update my findings. Thanks.
^ Thanks.
Yesterday morning it smoked heavily on startup. I drove 220 miles at 3'000 rpm's cruising, various loads etc. It ran perfectly and I checked the oil level at my destination which seemed fine. This morning I started the engine and didn't notice any smoke but it was a bit breezy. I've just had a similar return journey of 220 miles under all sorts of engine loads. It'll be interesting to see what the oil level is when I check tomorrow. I don't see smoke behind me and the rear of the car's clean.
Yesterday morning it smoked heavily on startup. I drove 220 miles at 3'000 rpm's cruising, various loads etc. It ran perfectly and I checked the oil level at my destination which seemed fine. This morning I started the engine and didn't notice any smoke but it was a bit breezy. I've just had a similar return journey of 220 miles under all sorts of engine loads. It'll be interesting to see what the oil level is when I check tomorrow. I don't see smoke behind me and the rear of the car's clean.
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