Car producing white smoke after a dead battery

Maintenance/Repairs
,
1

I have a 2011 Subaru Outback. The car is 12 years old, but the battery is just under 2 years old. I parked the car at my brother’s house before leaving on an 18 day trip. On day #8 of the trip my brother back home needed to move the car and reported to me that the car wouldn’t start. This is unusual for the car as it routinely goes 1 week or 1.5 weeks without being started.

Doing a traditional jump start wouldn’t work, nor would the car start after it was plugged into the house via an extension cord. When I got home (after my 18 day trip was over) I was able to source the problem to an EXTREME level of corrosion building up on the battery. After cleaning off the battery the car started. It didn’t take much effort to start the car, it simply needed a clean. Car runs fine, sounds fine…

THE PROBLEM: The exhaust pipes are emitting very heavy white smoke + oder. If not for that white smoke I’d say nothing was wrong with the car other than the car not moving for 18 days.

Is this smoke something to be expected, some sort of buildup that needs to be cleared out, or is it a sign that something is seriously wrong? I turned the car off right after noticing the smoke and haven’t given it a chance to determine if it just needs some time to “clear out” a residue or if I’m on the verge of blowing some kind of gasket.

In the 18 days I was gone my brother probably turned the key 40+ times trying various methods to get the car running (jump starts & what not) and perhaps that caused some kind of buildup. The car was also outside for 18 days and in that time the temperature has had some extreme shifts dropping as low as -15 (F) for a few days and now we are in a warm streak with temperatures in the high 40s.

I’m hoping its residue buildup and the car simply needs some time to run and clean out the engine. Or is this something that needs a mechanic ASAP? I wanted to ask you guys for your advice before I attempt to let the engine run for more than the short time I’ve had it running.

2 Likes
2

If the odor is sweet like antifreeze, get some strips from an autoparts store to dip in the coolant to check for the presence of exhaust gas in the coolant, indicating leaking head gaskets. This is always suspected on 4 cylinder Subaru’s.

If the white smoke stops after the engine warms up it may be just condensing water vapor from a cold startup.If it was any car but a Subaru, I would have put this suggestion first.

5 Likes
3

Charger was on for 10 days?

4

My hunch is there’s a buildup of unburned fuel and maybe antifreeze because of the long non-start period and a small head gasket leak.

Make sure the radiator and its expansion tank have enough coolant; also that there’s enough oil in the engine. Then drive it as usual.

Be on the lookout for more evidence of a head gasket leak.

2 Likes
5

Suggest to orient car so exhaust is facing downhill, engine a little higher than exhaust, then idle until engine coolant temp gauge shows normal operating temp, then increase idle rpm a little, say 1200, run until engine coolant fan turns on and off a couple of times. Should heat up the exhaust system enough to eliminate any water (or fuel) that has accumulated. Does that reduce the amount of white smoke from tailpipe?

I had similar problem on my Corolla. I can’t drive car on road as I used to, so I idle once a week (for Covid related reasons) to keep everything lubed. This idling routine causes water to accumulate in exhaust system, and the result was a lot of whitish smoke out the tailpipe. Fixed by doing the above routine.

1 Like
6

I think he wants to get the car from his brother’s house and back home. Driving it should do that, and heat up and clear out the exhaust. No need for lengthy idling.

7

It was plugged into the house for maybe 16 hours at most. It plugged in overnight. Then when the weather was warmer my brother tried one more time for 4 hours hoping the warm weather would get the car to start.

8

My main objective is to figure out:

  1. How to clear out that white smoke

  2. Is reving the engine in its current state going to blow something and cause major damage?

9

I’ll try this. Thanks

10

Well I just wouldn’t assume you are getting the full story on trying to start the. Wouldn’t. Be the first time that something unusual was done and just won’t own up to it. Just tow it to a shop to have it looked at. Tried for four hours to start it? Free parking is nice but I always keep the key.

11

Maybe take the radiator cap off before starting the engine and see if there are bubbles coming up. If your radiator is full and your overflow has some coolant in it you can skip the radiator cap and see if there are bubbles in the overflow tank. If there are, take your Starbucks money and start putting in a piggybank, you’re gonna need it.

12

Buy your brother a tutorial on basic auto maintenance. Had he known what snow corrosion on a terminal means, how to clean it with a pilers and baking soda, how to coat the terminals with dielectric grease when they’re clean and dry before putting the cables back on, he would have saved you and him hours of time.

13

If someone dropped off a vehicle for free storage and expected me to perform maintenance on a neglected battery, he would receive a “tutorial” from me. The vehicle should be in reasonable condition so it can be moved when necessary.