Saab turbo smoking on first start up.

[Boosted LS1]

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.

[Boosted LS1]

Thanks. Compression is even on all cylinders after I fitted a new head gasket and rebuilt the head. I do expect to find some oil residue in the pipe work in which case I'll swop the turbo. I'l have a better idea tomorrow, hopefully.

[Boosted LS1]

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.

[Boosted LS1]

^ Yes, I refurbished the head 4'000 miles ago. New stem seals fitted and the valves were lapped in. New gasket, new bolts etc.

[Boosted LS1]

^ 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.

[Boosted LS1]

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.

Edited by Boosted LS1 on Monday 17th December 09:18

[Boosted LS1]

^ 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.

[Boosted LS1]

Yes, I've not looked inside the inlet yet but I doubt it's full of oil. I'll do a load of miles over the next few days and see what happens. :-)

[Boosted LS1]

^ 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.

[Boosted LS1]

I checked the oil level and it seems pretty much as it was before so I've not lost oil over the last 400 miles or so. I got some smoke on startup but nowhere near as much as previously.

I think an oil change is on the cards just in case the rings are being problematic when cold.

[Boosted LS1]

^ Thanks. It does get worked from time to time but not thrashed. I'll enjoy doing that :-)

[Boosted LS1]

So, an update.

The car's certainly smoked less since I topped the engine up with 5/30 but there's still some smoke after I drive 100 ft or so. The smoke isn't immediate which is why I'm leaning towards the oil rings and not stem seals. I can't imagine rings or seals on all cylinders developing a simultaneous fault though.

Yesterday I changed the oil for a fully synthetic 5/30. The car definetely runs smoother. This morning after a 100 ft or so I had a lot more smoke then previously, with the the 15/40.

I'll have to wait and see what happens over the next week or so.

[Boosted LS1]

GreenV8S said:

Is it possible the turbo is seeing too much oil pressure when the oil is cold, and it is blowing past a seal?

I did think it was a turbo seal Peter hence swopping the turbo. Now it's either duff rings on all cylinders (unlikely), an oiling issue/pcv, or a stem seal. The engines transverse, canted forwards towards the exhaust side but oil had good drain back to the sump. I'd be surprised if the valve stem seals are submerged in oil. I'll have to remove the cam cover if nothing improves.

[Boosted LS1]

GreenV8S said:

Boosted LS1 said:

I did think it was a turbo seal Peter hence swopping the turbo.

Have you checked the oil supply and return line restriction?

^Thanks.

The oil supply is unrestricted and the drain pipe is 1/2" dia. I'm going to park the car on the tilt for a few nights to see if that drains the oil away from around the valve stems. I'd be surprised if they're submerged in oil once the engine's been standing for a while but it's an easy test. I can also loosen the exhaust header and look for oil the following morning.

[Boosted LS1]

^Thanks, It doesn't have a boost guage but I intend to fit one. The turbo was replaced with one that I used on a former engine. The car pulled better after the replacement but feels 'normal' now. The turbo hangs underneath the exhaust header and I have seen oil on the mounting flange, ie above the turbo cartridge. I'll take a closer look at the turbo I removed.

[Boosted LS1]

Thanks guys, it's a 9000. B234 engine, t25 turbo.

As for the stem seals, the top end kit was BGA. The stem seals are stiff to press on so I doubt one has fallen off. The car's done over 4000 miles since I refurbed the head.

I've just ordered a boost guage.