this post was submitted on 28 Oct 2023
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Mechanic Advice

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I drive a 2008 4runner with 85k miles. It's been receiving by the manual maintenance for its whole life.

Recently I have started noticing a gas smell when I start the car in the morning. It seems to dissipate after a few minutes. I also don't really notice it on subsequent starts on the same day if I take the car out multiple times. Or if I do, it's less pronounced.

There is no visible leak or gas on the driveway that I can see.

Any ideas? I'm planning to take it in but figured no harm in asking here to see if anyone knows what I might be dealing with first.

Thanks!

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[–] czardestructo 8 points 1 year ago (1 children)

Totally normal for any car to run rich, especially on cold days while the engine warms up. Rich just means the engine is operating with slightly more gas than necessary as it's safer during warm up though its less efficient and that's why you smell gas. The un-burned fuel is just going right out the tail pipe. Sniff back there to confirm.

[–] theragu40 1 points 1 year ago (1 children)

Interesting! I am pretty sure the smell is stronger by the exhaust. That would make sense!

So even if it just seemingly started out of nowhere, nothing to worry about?

I really appreciate the reply!

[–] czardestructo 2 points 1 year ago

Nope no problem it's just the colder weather. It just needs to operate in the warm up mode for longer to heat up the oil and coolant until it go into normal operation and stop wasting gas. Perfectly normal. Some cars are a lot more aggressive for warm up. Subarus, especially old ones, can sound like a broken tractor while warming up then the engine quiets down and sounds normal.

[–] Everythingispenguins 2 points 1 year ago (2 children)

Is this gas smell only outside of the vehicle or can you smell it inside. If it is inside that is a much bigger problem. As brain cells and gasoline don't get along.

So a few thoughts - Could be normal because of the cold start. Though if this is a new thing there is probably something new that is being exasperated by the cold start.

Hole in the exhaust system. This is letting you smell the normal exhaust smell where you are not used to smelling it. (Still dangerous to the brain)

You have a leaky fuel injector which is leaking into the cylinder and causing an extra rich start. This would be more likely to cause the smell on hot restarts.

Leak in the fuel system. Which goes away after the engine is warm due to expansion resealing a gasket or something.

Do to the dangers associated with fire and brain cells quitting. I would recommend you take it in sooner than later. You will probably have to leave it overnight so they can do a cold start on it.

[–] theragu40 1 points 1 year ago

Good question on the inside vs outside thing. It is definitely more pronounced outside. I'm usually loading kids so the doors are open when I start the car in the morning. I'll have to do a test with getting in first then starting.

[–] theragu40 1 points 1 year ago

Just checked this morning and it is not detectable inside the car. And it is definitely stronger near the exhaust (and/or is coming from the exhaust).