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Q: What's wrong with my car?

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It sometimes hesitates to start and will sometimes puff out white smoke out of the exhaust but not often. A few times I've smelled coolant while driving but not recently. It's slow on acceleration from a stop and once cut off on the highway. It now feels like it doesn't want to accelerate after changing spark plugs. I couldn't go over 25mph before then. It is also shaky when I drive it and the coolant runs out fast. Also one day my oil was clumpy on the stick when I checked it but it hasn't done it again. Please help me, thank you.

My car has 142150 miles.
My car has an automatic transmission.

A: Hi there, thanks for writing in. Without be...

Hi there, thanks for writing in. Without being there to inspect your Nissan Altima's engine on site, it's very hard to give you an exact diagnosis. However, the white smoke and smell of coolant leads me to believe that you might have a blown head gasket or it's leaking. The white smoke tends to be caused by coolant in the oil. If the oil is "clumpy" or "milky" this is also an indication that you've got coolant leaking inside your engine block. Best bet is to have a professional mechanic inspect your vehicle for smoke coming out of the exhaust pipe. This will allow them to eliminate some issues and pinpoint the source of your problems.

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