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Car Forum / Saab Cars / March 2006Yikes! Puff o' smoke...
1987, T16 Aero. Coming up the motorway on Sunday I thought I noticed a "puff" of smoke from my exhaust. The only way I could reproduce it was thus... 1/ Floor it and get it flying, (80mph ish in fifth gear) 2/ Let go of the throttle and ride on the overrun for about ten seconds 3/ Floor it again.....single puff of whitish smoke. At no time do I change gear or over rev the engine, I generally try to change at no higher than 4000rpm, but sometimes go to 4500rpm. In addition despite several attempts, I only reproduced the phenomenon once... She doesn't smoke under normal circumstances, and I don't get the classic turbo smoke if I leave her standing running for a while. What's going on? I don't appear to be losing oil, I'm not aware of any sign of a head gasket problem. Could this be un-burnt fuel just smoking off in the exhaust system, i.e. nothing to worry about OR is my beloved C900 about to go pop.... Thanks Al > 1987, T16 Aero. > Coming up the motorway on Sunday I thought I noticed a "puff" of smoke from [quoted text clipped - 3 lines] > 2/ Let go of the throttle and ride on the overrun for about ten seconds > 3/ Floor it again.....single puff of whitish smoke. My old T16 used to do this. It isn't whitish smoke, honest, it's a healthy blue/grey, burning oil type smoke. It just looks white in the mirror. > At no time do I change gear or over rev the engine, I generally try to > change at no higher than 4000rpm, but sometimes go to 4500rpm. In addition [quoted text clipped - 6 lines] > of a head gasket problem. Could this be un-burnt fuel just smoking off in > the exhaust system, i.e. nothing to worry about You are burning oil, but a very small amount of it. It gets sucked in during overrun, builds up, then gets burnt off in one go when you floor it. There are two things that cause a T16 to do this: leaky valve stem seals and leaky turbo seals. In most cases, it's the valve stem seals. As such, I'd do them first. > is my beloved C900 about to go pop.... No, far from it. It will slowly, gradually smoke more, until you fix it. If I were you, I'd do nothing right now, and schedule the work in for next time you're doing some major work on the engine.  SignatureGrunff <snip> > is my beloved C900 about to go pop.... Sounds like blow-by gases building up in the crankcase and re-cycling when you boot it again. I wouldn't worry. Do T16s have an oil separator in the crankcase, like T8s do? Might be worthwhile pulling the crankcase off and giving it a clean. Paul 1989 900 Turbo S http://saab.go.dyndns.org/ My 86 900T started doing that, a little puff at first and it went away. However, after time the smoke just started coming more frequently, until it was a health hazzard. it was the turbo. It died. the seals were all rotted and oil was bloing into the system. You could be at the beginning of the same thing, after all the car is nearly twenty years old. My dealer said that the turbos usally start to go after ten. Jeremy http://Jerem43.home.att.net > 1987, T16 Aero. > Coming up the motorway on Sunday I thought I noticed a "puff" of smoke [quoted text clipped - 23 lines] > > Al My '88 9kt started doing that when I coasted to a stop at the bottom of a long expressway exit. I switched to 10w40 synthetic oil, and it practically stopped smoking. >My 86 900T started doing that, a little puff at first and it went away. >However, after time the smoke just started coming more frequently, until it [quoted text clipped - 34 lines] >> >> Al > 1987, T16 Aero. > Coming up the motorway on Sunday I thought I noticed a "puff" of smoke from [quoted text clipped - 22 lines] > > Al My guess is the seals in the turbo are wearing out. When you let off the gas after hard throttle you have a lot of vacuum in the intake side and the turbo is spinning fast, oil gets past the shaft seals. My turbo has always whistled....is this a bad thing? :-(( I kinda liked the sound, it certainly doesn't screech and I was only able to reproduce the smoke once out of four or five attempts.(He said re-assuring himself) If it's turbo repair time what's best option? New (gulp) turbo now before it gives up completely or a Turbo rebuild? OR cheapskate option, pull one off a scrapper? If I do this what should I be looking for? Please bear in mind that my mechanical knowledge is at enthusiastic amateur level, that's why Phil and Phil at Aeromotive do most of my mechanicals for me. PING Paul Halliday, didn't you get your turbo rebuilt somewhere local to us? (I preffered Grunffs valve seals idea....) Al A higher than usual whine is a sign of turbo death. I picked up a rebuilt unit for $300 US. Checkout your local auto shop, they might be able to order you a rebuilt one. Rebuilding one can be problematic. If there is any cracking of the housing, it shouldn't be rebuilt. At least with one that is a professionally redone, you will know that the unit has be inspected for any flaws (hopefully) in the housing. The biggest issue in replacing the turbo isn't getting the replacement, it is getting the old one out. On mine, the mounting bolts had decayed and two snapped off on removal. That is where the large cost will be. It actually cost me more to have the new turbo installed than the turbo itself. Jeremy > My turbo has always whistled....is this a bad thing? :-(( > [quoted text clipped - 15 lines] > > Al I was "thinking about it", since mine whistles. It whistles, rather than whines ... and I have heard a kippered turbo. It sounded like a helicopter! There _is_ a place in Birstall that does turbochargers, which I think Aeromotive use for their special turbos. Ask them about it :) Otherwise, I wouldn't expect to pay more than 350 UKP for a new (reconditioned) turbo unit. > I was "thinking about it", since mine whistles. It whistles, rather > than whines ... and I have heard a kippered turbo. It sounded like a > helicopter! There _is_ a place in Birstall that does turbochargers, > which I think Aeromotive use for their special turbos. Ask them about > it :) Otherwise, I wouldn't expect to pay more than 350 UKP for a new > (reconditioned) turbo unit. Sorry - this is in reply to Al's last post. I have been experimenting with Google's groups whatsit and erm, this posted without reference to what I was posting in reply to :( Oh well ... Back to good old Entourage :) The company are AR Turbo Engineering. <http://www.arturbo.co.uk/> <http://www.the-business-search.co.uk/biz/131530-A.R-Turbo-Engineering-Ltd> ... And the Northern office for BTN Turbo: <http://www.btnturbo.com/contact/default.asp> - See bottom of page. Paul 1989 900 Turbo S http://saab.go.dyndns.org/ > I was "thinking about it", since mine whistles. It whistles, rather > than whines ... and I have heard a kippered turbo. It sounded like a > helicopter! There _is_ a place in Birstall that does turbochargers, > which I think Aeromotive use for their special turbos. Ask them about > it :) Otherwise, I wouldn't expect to pay more than 350 UKP for a new > (reconditioned) turbo unit. The simple solution is to continue using plenty of revs in the gears of his 20 year old car and the problem will disappear - in a puff of smoke. >> I was "thinking about it", since mine whistles. It whistles, rather >> than whines ... and I have heard a kippered turbo. It sounded like a [quoted text clipped - 6 lines] > his > 20 year old car and the problem will disappear - in a puff of smoke Yeah. Must try that one...... Hey ho, if the turbo goes boom I'll pull one off a scrapper if I can. Short of that, I'll break her myself, sell the parts on ebay and make enough money to buy another car. (Worth more in parts) Thanks for the replies, I'm less worried than I was, but am making financial arrangements to face a major bill in the not too distant future. Al
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