Hello there everyone... back in the Volvo game once again. I have a 2010 Volvo S40. I have white smoke coming from the exhaust when I try to accelerate hard, like flooring it. If I drive it like an old lady (No offense to any readers), that is, slow and gradual acceleration, I have no issues. The only code I'm getting is a stuck MAF sensor, and it seems to be a generic one at that. Coolant levels are good. Don't seen any milky residue on the oil cap. Oil looks fine also. Not overheating, at all, but I know that can still mean a bad gasket. I know white smoke is almost certainly the head gasket, just trying to rule out any other possibilities before I start tearing down the block. I've heard of some weird issue with the turbo causing this, didn't know if there was any truth to it. Any help would be GREATLY appreciated my friends...

 

White smoke is steam vapor in a gas engine.

I'm not aware of anything on the turbo that would do that unless you have an internal coolant leak in the turbo. If so, its junk.

 

Thanks for the quick response tony1963! Is there anything I can do to test to see if the turbo has failed? Or perhaps to get a true read on a blown head. I'm thinking a compression test is the best way to go, just trying to see if there are any little Volvo tricks I may be missing. I've heard that some Volvos can run with a partially damaged gasket, as long as you keep coolant and drive lightly? Any truth to that?

 

Most cars can run with a gasket failure as it eats up coolant, etc. There are no tricks other than a diagnosis and conclusion. The only conclusion that you will draw is that there is some type of leak.

There are methods to test for combustion gasses in coolant or pressurize the cooling system and see if the coolant bubbles.

Another way is to look at the spark plugs. If one or two have white ashy deposits, that is commonly a sign of cooling system byproducts.

 

dunno if you can do this on the S40s but on the 850s you can pull off the top hose to look into the turbo and see if there's any bearing play. Also the turbo does have a seal that can give way and leak water and oil. Tony's suggestion about looking at the plugs is a good one - sometimes head gaskets leak between cylinders so not all the plugs will look the same. If the turbo is blowing oil/coolant into the intake you'd see some film in the tubing and intake, risk a dirty MAF and throttle body or would see it push out the exhaust. A dry/wet compression test can also help determine if there's any compression leakage. You should see a consistent 150 or so PSI across all cylinders.

 

Thanks so much guys for all help... all my tests came back a negative on the blown head gasket. BUT... the plot thickens it would appear. When I ran my scanner on it, I pulled a MAF code... the original one DEFINITELY needed to be replaced. And I remember a similar issue on my 940, though it was non turbo. So I replaced it, and things seem to be good. Took it for a quick drive, no issues until I tried to give it some gas, and then I got the infamous "Reduced engine power". Turned it off, to go grab my scanner again, engine was back to normal, no codes. Everything seemed fine once more. Gave it some gas again while parked, got the reduced engine power warning, and code P0607 - which is a control module fault. Turned it off, back on again, no issues once more. It seems I only get the code when I try to put that turbo under load... so am I leaning toward the turbo being a wrap? Mind you, I only have 133,XXX. And from what I can see, this S40 seemed to be taken care of.

 

probably not the turbo, they are pretty stout. I'd be looking for something like a tear in a hose or a hole in the intercooler which can bleed off boost confusing the ECU. Also, these cars are very sensitive to the MAFs, particularly after-markets that may fit but are not quite spot on exact. What happens if you put the original MAF back in?

 

The reduced power message was a faulty Fuel Pressure Sensor on my 2005 T5. The sensor tells the fuel pump to increase or decrease fuel pressure through changes in voltage.