Inexpensive way to reduce blue exhaust smoke?


#1

My 12-year-old car has started to blow blue smoke from the exhaust when starting after sitting overnight or longer on cold days. The smoke stops within a few seconds. I assume this means that oil is dripping into a combustion chamber and burning off, and that the rings are sealing better when the engine gets warm. But the car isn’t using an unreasonable amount of oil between changes. The smoke is embarrassing more than anything else. Is there a cheap, easy way to reduce the smoke? The car really isn’t worth expensive engine repairs.


#2

I would suggest thicker oil. That should reduce the symtoms. Be careful though, it might put some extra strain on your oil pump,


#3

What you’re describing is typically the result of failed valve seals. They get old and hard, and no longer stop oil from running down the stem of the valves. The smoke stops because there’s not usually much oil that remains on the valve stem once the engine is running.

Having said all this, cheap is relative. Is this a cheap repair? No, not especially, but it’s cheaper than an engine overhaul or a new car. Thicker oil might help, but it’s not likely, and if it does that will be a temporary fix too


#4

I agree, price replacement of the valve seals and decide if it is worthwhile.


#5

The oil burning is from old/worn valve guide seals.

These seals prevent oil from leaking down the valve stems into the combustion chambers. As the vehicle sits after being operated, oil accumulates in the cylinders, and when the engine is restarted later, the accumulated oil burns off.

One thing you might try at the next oil change is use one of these high-mileage motor oils, such as Valvoline Max-Life. These oils have special additives that cause old/worn seals to swell slightly. And this might be enough to prevent the oil from leaking past the old/worn valve guide seals.

Tester


#6

Year, make, model would be helpful as different engines have different seal configurations. One inexpensive solution, switch to synthetic oil. These lubricants smoke very little when they burn…


#7

Thicker oil may not stop smoking at startup. It could; but not always. If it smokes for longer than five seconds, it might help a little.


#8

I concur it’s probabaly valve seals…With that said…I would just leave it alone. I’ve seen cars go YEARS and THOUSANDS of miles with bad valve seals. The car is 12 years old…why waste the money. As for using a thicker oil. Don’t bother. The problems it may cause outweigh the little difference the thicker oil will make.


#9

A car that old may not be cost-efective to fix. A puff of blue smoke on startup is almost always a leakdown of oil past the valve guides. I would get an estimate anyway. I had a 1984 Chev Impala which had this and just kept driving it, since the rest of the engine was in good shape. My son sold it with over 250,000 miles on it and it probably still running. It may not pass an emission test if your state requires such a thing. Make sure you go for the test with a warmed up engine.


#10

If the car’s worth keeping, a full top end job should be done. As long as the heads are off, do the whole job.


#11

The cheapest way is to try those high-mileage oils. They include additives that will soften and swell old seals. The next try is to replace the valve stem seals. This can be done without removing the cylinder head. But should only be attempted by a skilled mechanic. It would require using an adapter to have shop air hold the valves in place while removing the spring retainer and spring to get to the seal under them.


#12

You could be less embarrassed if you put a filter in the tail pipe. Maybe, a wad of fiberglass?


#13

Another option is to remove the spark plug, feed long lengths of soft rope into the cylinder, and manually rotate the crankshaft until the piston pushes the rope to hold the valves shut.


#14

Feed a rope into the chamber… ha. That’s a good one! Might as well feed the car spaghetti and meatballs, and dont forget the garlic bread! My my 1989 305 has a small puff at startup. I bought the car with 49k miles in 2018. I feel like maybe the prev owner rolled back some miles on the odometer for me. I’m gonna get a nice oil change and see where it goes. I doubt it’s been done in a while since when we checked the brake fluid it was black and that had to be changed too.


#15

Great job. Re-opening an 11year old post and adding nothing useful. BTW The rope trick to hold the valves up/closed is a completely time tested and useful way to do it.


#16

Perfect timing. Saturday’s rerun covered this topic.
Now this is not from that show, but similar from Dear CarTalk, May 1, 2000
RAY: And although we couldn’t get the scientists at JC Whitney to divulge their
“pelletalogical” secrets, our guess is that the magic pellets must somehow melt
against the cylinder walls, thickening the walls and therefore closing the spaces
between the walls and the piston rings (Note: this is complete and utter
speculation on our part – and therefore, probably bull-feathers).