Strange engine odor

December 21, 2006 3:51 PM

Why does my engine smell like butterscotch?

Seriously... after running for any length of time, my engine has an odor that can only be described as butterscotch-y.

What could be causing this?

posted by I_Love_Bananas to travel & transportation (23 comments total)

Radiators tend to have a maple syrup-y smell. Do not know why, though. I am a whole lotta help, huh?
posted by Sassyfras at 3:53 PM on December 21, 2006

a prankster put some Twinkies under your car hood?
posted by matteo at 3:55 PM on December 21, 2006

Twinkies smell like butterscotch?!
posted by Sassyfras at 3:56 PM on December 21, 2006

if you fry them on your car's engine, maybe
posted by matteo at 4:03 PM on December 21, 2006

Anti-freeze smells (and tastes) sweet (that's why it's a danger around pets)... Maybe you're leaking anti-freeze and smelling the aroma?
posted by amyms at 4:14 PM on December 21, 2006

As sassyfras noted, the stuff inside radiators smells sweet. You probably have a minor coolant leak. Somewhere in the system, hot coolant is escaping,. maybe even onto the hot engine block, which would make it smell even stronger. Try parking your car over a piece of cardboard and running it until it's hot. Then watch for drips.
posted by cosmicbandito at 4:18 PM on December 21, 2006

Probably a coolant or antifreeze leak. Have your mechanic check the radiator and hoses.
posted by letitrain at 4:18 PM on December 21, 2006

Maybe a coolant leak. Antifreeze burns sweet because it's made out of glycol. See if your dipstick is muddy or frothy.
posted by Brian B. at 4:23 PM on December 21, 2006

On preview, agree with Brian B.

You could also have an internal engine problem, such as a head gasket leaking coolant into a cylinder. Over the long run, that will produce lots of diagnostic engine problems, the classic ones being a good deal of white exhaust smoke on start up, and discolored/frothed motor oil; but if the leak is very small, or located so as to be leaking into adjacent cylinders, there may not be much smoke at start, and yet still enough coolant being pulled into the combustion chamber(s) to produce a sweetish exhaust smell, which is pretty pungent.

A compression check, "reading" the spark plugs, and checking the oil and coolant systems for overpressure and contamination can reveal much about internal engine condition, if no obvious external coolant leak is found first.
posted by paulsc at 4:31 PM on December 21, 2006

Rather than butterscotch, could it be that you're smelling caramel? That could be from ethylene glycol getting hot.

(By the way: ethylene gycol does taste sweet, but it's also poisonous.)
posted by Steven C. Den Beste at 4:32 PM on December 21, 2006

This thread is making me hungry.

Oh, and yes, most likely coolant. Though it may not be such a dire situation - make sure you check all hose connections as well. It could just be dripping out onto a hot exhaust pipe and creating that smell. This also might make it hard to find the exact location of the leak when parked over cardboard - sometimes the drips burn up on the pipes, or trail somewhere else before hitting the ground.
posted by krippledkonscious at 4:39 PM on December 21, 2006

If you do discover it's an antifreeze leak, particularly one that is leaving it behind on your driveway, you may want to take a few steps to clean it up. As stated above, it's really bad for pets who seem to be drawn to it like it was God's-own-nectar.
posted by quin at 5:56 PM on December 21, 2006

What type of car is this, by the way? Please tell me it's not a GM with a plastic intake.......
posted by IronLizard at 6:08 PM on December 21, 2006

It could also be a transmission fluid leak...... trans fluid also has a peculiar smell if it is for instance dripping onto to your exhaust......

I would start by checking all fluid levels before every time you drive the car, and make notes...... your owners manual should tell you how to do this..... and then see what fluids are going down and how fast..... it is normal for a car to use a little oil and windshield fluid..... but the other fluids should not be consumed by your car......

but, usually, if you are losing precious fluids, at a rate that will harm your car in the short-term, you will lose all of a particular fluid at once......

If you are not able to do check them out yourself, have your car looked at by your trustworthy mechanic......

You do have a trustworthy mechanic, don't you?
posted by peewinkle at 7:40 PM on December 21, 2006

Have a UV light or LED? Most antifreeze has a fluorescent dye in it. Wait until night, shine the light on the engine. Coolant leaks will be obvious.
posted by eriko at 9:57 PM on December 21, 2006

It's a Taurus... all good ideas and I will have it checked. Have not noticed any blatant under-car drips or pools of coolant, but that doesn't rule out a more insidious issue.

Thanks to all!

BTW- what IS the difference between caramel and butterscotch, anyway?

I don't know that I could tell the difference in the smell.
posted by I_Love_Bananas at 4:52 AM on December 22, 2006

It's a Taurus.

Fords are notorious for antifreeze leaks. Often untraceable.

If you own a Ford, you will smell that smell sooner or later.
posted by Max Power at 5:15 AM on December 22, 2006

BTW- what IS the difference between caramel and butterscotch, anyway?

Caramel is just cooked sugar -- candy, basically, that hasn't even reach the thread stage of candy making. Heat sugar slowly, stirring constantly, until it reaches 170C/340F and hold there until it is done.

Butterscotch has butter, cream, and often vanilla mixed in with the sugar, and is only cooked to at least the soft-crack stage -- 280F. The difference between Butterscotch and toffee? You cook toffee up to hard-crack, 300F.

Caramel candy is candy made with caramel -- two processes.
posted by eriko at 7:41 AM on December 22, 2006

If it's the V-6 Taurus, odds are you are losing a head gasket, especially if it's the 3.8. The Ford 3.8 is well-known for head gasket problems and has had several recalls/warranty extensions over it. We just replaced the head gaskets in our Windstar minivan two years ago at 120,000 miles or so, at a cost of approximately $1400.

And it's smelling like antifreeze again, by the way.

GRRR.
posted by mr_crash_davis at 7:44 AM on December 22, 2006

And it's smelling like antifreeze again, by the way.

Every Ford I've ever driven, from Mustangs to their biggest vans,(name escapes me and I drive one quite often for work) 80's to 90's Crown Vics, et al.

They will ALL start smelling like this. get used to it.
posted by Max Power at 8:48 AM on December 22, 2006

Diacetyl, or 2,3-butanedione, often contributes to a buttery or butterscotchy smell or flavor. I doubt this will be useful to you, but it may be interesting.
posted by ikkyu2 at 2:28 PM on December 22, 2006

Not just the head gaskets, the intake gaskets go too, sending coolant in with your fuel air mix. (The GM's intakes just melt and pours it in through holes in the egr passage).
posted by IronLizard at 4:10 PM on December 22, 2006

Holy Jugs! That sucks!

So I guess your answer, Bananas, is that Butterscotchness = Buy Un-American. A tough lesson indeed.
posted by krippledkonscious at 1:56 AM on December 23, 2006