I’m driving my wife’s 2002 VW Golf on the highway to build miles (it’s at 84k). It’s a manual with gearing that’s at 3500 rpm at 70 mph in 5th gear, which seems pretty high. It had been doing fine on the highway, even though the RPM seems a bit high due to gearing, but it keeps me under 80 mph (highway is largely 70 mph). It burns oil, but not too bad, like a quart every 500 miles or so.
Recently, when driving at “high” speed (slightly over or near 70 mph), I get a plume of intense white smoke. After slowing down, the plume goes away, and I can continue near 65 mph.
After this happened today, I put on a code reader, and saw of P0159, air fuel ratio oxygen sensor issue.
Any ideas on what causes the white plume of smoke, and what to do about it? Seems like the car should have more miles on it.
You say the engine is burning oil already. Do you notice any exhaust smoke at startup?
The white smoke at highway speed could be oil as well. Try this. Get up to highway speed, then let off the gas completely for several seconds, then give it gas again and look for smoke. If that causes a big puff of smoke, oil is being sucked into the cylinders, possibly through worn valve guides.
The “smoke” may also be coolant being sucked into the engine through a bad head gasket. Have you noticed any loss of coolant? When engine is cold, check coolant levels in both the radiator and the overflow tank.
What is the blue smoke test? There isn’t anything electrical.
Just to be clear, the car drives fine, it’s going well, gets like nearly 30 mpg, and then, after about 20 minutes at 73 mph, a big white cloud of white smoke comes out until I slow down. Once slowing down, the smoke stops, and I can continue at a slower speed without any issue.
There is no smoke at startup, or while normally driving at highway speed. It’s only after being at 73 mph for a solid 20 minutes that there is the quite massive plume of white smoke. This has happened about a half-dozen or more times (different days), with sometimes cars behind me swerving to avoid the smoke.
Could this be caused by the oxygen sensor? Can I keep driving (sometime having this issue) or is this causing any permanent damage?
Unlikely to be O2 sensor related. If you have access to the factory shop manual, you can read what it says are possible causes of that code and what procedures are required to find out which one it is.
First guess would be compromised head gasket. If so, you should be noticing some loss of coolant. Use a Sharpie pen to mark the level of the coolant on the plastic bottle first thing in the AM, then check it each day at the same time, before first drive of the day. If it is steadily going down, ask your mechanic to do the necessary tests to check for a head gasket problem. And monitor the coolant level carefully. You don’t want it to run dry. You may have to remove the radiator cap to double check, as the plastic bottle isn’t always a good measure of the coolant level, especially when coolant is being lost.
After the head gasket, my second guess would be a way-overly-rich mixture, likely due to some problem in the fuel injection system. A fuel pressure test would be a good start to rule that in or out. It’s odd though that you don’t notice the engine sputtering a bit when this happens.
500 miles per quart is sort of right on the line between excessive and “more than normal, but ok” oil usage. Still, I wouldn’t consider an oil-control problem to be the most likely cause of your white-smoke symptom. But it would be third in line, after the head gasket and the fuel mixture problem.
A friend with an old Rabbit diesel years ago described driving at 65 mph, a blue/white plume appearing behind him, and the car began accelerating by ingesting its own crankcase oil for fuel. He would brake it down to 50 mph and all was normal until he tried 65 again. He never drove over 60 after that happened twice. Valve seals or rings? Don’t know.
Okay, I seem to have decreasing coolant levels after marking it and tracking. At first, I did look at washer fluid, before I quickly realized my mistake. I also noticed that while driving at steady highway speeds, the engine coolant level shifted dramatically, going all the way from 190 to dead cold at times. That isn’t normal, right?
Someone suggested a warped or cracked head gasket that leaks when the pressure builds up. Is that something expensive to have detected and fixed?
The car is still good with driving around town or short highway trips.
No, it isn’t normal at all for the coolant temp to go from 190 to cold, not once the engine is warmed up. Maybe some of the experts here know if this symptom is consistent with a compromised head gasket or not.
If your only symptom was that the coolant temp varied like that, I’d suspect a sticking thermostat. It might pay to have that checked on your car, as doing so, even if it needs to be replaced, is usually an inexpensive procedure.
But the loss of coolant, and no visible signs of leaking, along with the puffs of white smoke … hmmm … I’m thinking you are looking at a gasket problem of some kind or another. It would’t necessarily be the head gasket, the intake manifold gasket, or even the throttle body gasket could cause this symptom on some cars, depends how the coolant routing is done. Shops have tests to determine where the leak is happening.
A quart of oil per 500 miles is a bit much so my suggestion is with the others; a dry/wet compression and/or leakdown test.
I assume you’re referring to engine coolant temperature so that could point to a faulty thermostat, excessively low engine coolant, or flaky temp gauge or gauge sending unit.
The oil consumption is an issue and that really needs to be determined. At this point I wouldn’t worry too much about a head gasket problem as coolant loss could be something far less serious.
There are several other tests that could be performed to weed out head gasket issues, etc and a compression test is one of them.
Regarding insightful’s friend with the diesel Rabbit, that problem could have been due to a failed diaphragm in the vacuum pump.
The O2 sensor code is a symptom, not a cause. The sensor is very likely covered with oil residue and no longer able to function properly. A quart every 500 miles will do that. Your cat converter is probably just about shot too… for the same reason.
I think you need to do a compression test as well as a cylinder leakdown test. Post back with the results. I suspect the results will show that your engine is in the autumn of its life.
Interestingly, there was a recent call from someone with a Subaru and the same symptoms, white smoke coming out the back. Click and Clack described it as the head gasket, and said eventually the problem goes away when the motor runs out of coolant and the engine overheats and stops.
Question: If I keep my eyes on the coolant level, ensuring that it doesn’t drop too low, but still have the occasional puffs of white smoke (and the driving hazards that ensue), is there damage from the leak when pressure builds up? Is this something that I really need to get fixed soon, or does it slowly become worse and worse, eventually depleting all the coolant in a single trip?
The coolant leaking into the cylinder could cause some corrosion on the flat surface where the head gasket seats, which might add some machine-shop expense come time that you fix the leak. It also isn’t doing the exhaust system any good, and may add some considerable expense there if rust takes hold.
If hot exhaust gasses are getting into the coolant, that can make it very acidic and corrode the entire cooling system. There are chemical tests available to determine if this is happening.
Likewise, if hot exhaust gasses get into the coolant the extra pressure can damage things like blowing a hose and causing a major leak that depletes all the coolant in a matter of minutes, or even if it is just a slow build of pressure, ruining the radiator.
Whether any of this applies in your case, best to consult a shop.
While you are there ask them if a leak like this can be fixed by re-torqueing the head bolts.
Oil can come across as white in color. You’ve already stated this engine is blowing through a quart per 500 miles and that’s horrid. Do a dry and wet compression test.
I tend to agree with the same mountainbike that the engine is in the autumn of its life. A piston ring issue makes everything else moot points.