General Question

prioritymail's avatar

What causes a car engine to whistle upon accelerating?

Asked by prioritymail (1630points) August 23rd, 2011

Pretty sure it’s the engine, positive it’s coming from somewhere at the front of the car.

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25 Answers

sakura's avatar

Not a mechanic…but it could be that your fan belt needs tightening

augustlan's avatar

I would guess a belt, too. Though I think of that as a ‘squealing’ sound, rather than a whistle.

Afos22's avatar

If it’s a whistle, perhaps you have a hole in your exhaust system.

funkdaddy's avatar

If it’s not a belt as mentioned above then a leak in the intake or exhaust could cause whistling.

Also, if the sound isn’t necessarily new, cars with turbos will whistle when they accelerate as the turbo spools up.

See also

sakura's avatar

Just had a thought…do you have air conditioning? If so you could have a leak in the pipe, has it been working as efficiently as it used to? that whistles when it has a hole and sounds like it’s coming fromt he engine when in the car.

tedd's avatar

Need more of a description than a whistle.

My immediate thought is you have a belt going bad. If the whistle gets worse the faster you go, that would be indicative. As stated before its usually more of a squeal though.

Some kind of a hole in the exhaust system is also a possibility. But typically those are more of a “rumble” or it’ll sound like you put a tin can muffler on your car.

I would like to think you would know if you have a turbo on your car, which would definitely whistle. But it would whistle mostly (or most noticeably at least) when you shifted and it released all the built up pressure.

jerv's avatar

One that isn’t mentioned but has happened to me a couple of times; radiator cap.

Of course, that is merely a possibility, as I can think of a few things that will make a car whistle, including not rolling the window quite all the way up.

john65pennington's avatar

I drive a police car that had the same symptoms. Discovered it was a blown head gasket on the engine.

CWOTUS's avatar

I doubt if it’s a hole in the exhaust system; I think that would manifest more as a “booming” or other loud sound that would not be confused with a whistle. My first thought was also “loose belt”, but my second thought was that there may be a hole in the intake manifold or air filter housing. Air would definitely tend to “whistle” into that hole. (Air or hot gas coming out, as in exhaust, would be louder.)

Is the air filter in place? Running without an air filter – not a good idea! – will cause a whistling sound.

flutherother's avatar

A loose fan belt, especially in wet weather.

Tropical_Willie's avatar

Sometimes a water-pump that is on its last legs will make a NOISE.

prioritymail's avatar

Thanks for all the answers! It’s not the exhaust or the windows. Don’t have a turbo. The car is supposed to have a/c but the motor can’t handle the load or something so I don’t use it. Water pump has supposedly been changed recently. I haven’t checked…I guess I should. I think it becomes more noticeable as I accelerate but that it’s always there. I will look into belts, radiator cap, intake manifold, filter housing, air filter….head gasket :S… Thank you!

jerv's avatar

If the motor can’t handle the load of the A/C then there are some serious issues here, possibly related to the whistle. Loss of power is another possible symptom of a blown head gasket. I can’t think of any other single thing that would cause both whistling and taht degree of power loss… though I allow for the possibility that your engine has multiple problems as well.

prioritymail's avatar

@jerv Thank you for your reply. I am going to start Googling blown head gasket symptoms right now!

tedd's avatar

Blown head gasket could be it, but that would have to be a short lived problem as typically that leads to getting coolant into your oil and gumming up the engine. Does a lot of smoke come out of your tail pipe?

Take a look at your engine oil, if its “milky” then you blew a head gasket (more than likely).

jerv's avatar

True. A born head gasket generally lasts less than a week before the engine quits. Assuming that this has been going on for longer, I am leaning towards “multiple problems”. The head gasket is still possible though.

@tedd Of the three I’ve blown, none smoked. One lost power, one overheated, and one did both. Now, they do sometimes smoke, but the lack thereof is not a clean bill of health. The oil is also not an always thing. I recommend a compression test.

tedd's avatar

@jerv Oh I know, but its a pretty typical symptom, and very easy to spot.

prioritymail's avatar

Thanks both of you… I am going to check the oil and radiator today and see if I can find any evidence. There is no white smoke coming out of exhaust. I’m not sure how long it’s been going on. I have only driven this car for about two weeks, separated by about a month. I’m not sure if this was happening in week #1 but it’s been going on for week #2. It does not seem to be overheating, at least according to the temperature gauge which is planted in the reasonable middle between C and H. I suppose it could equally be “multiple problems” as this car also has transmission, brakes, and body issues (i.e. not well taken care of).

CWOTUS's avatar

If the car has been inactive for a long time, especially if it has been left outdoors, then squirrels and mice may have found places to store food and make nests. This is quite common, in fact.

I would suspect that this may be one of the problems with the A/C: these critters often find a way into the cabin air ducts and make nests there. (I once turned on my fan at the beginning of the winter season, to run my defroster and cabin air heater, and was rewarded with a shower of chewed-up acorn bits. The duct system needed to be partially disassembled and vacuumed, and the pieces pulled away from the fan itself.)

I’ve never known this to cause a problem with the engine itself, though, unless the coil wire or spark plug wires or some other crucial component is damaged past a point of being able to function.

prioritymail's avatar

Some new things I’ve noticed:

-The whistling seems to start around 20 mph and continue as speed increases but cannot be heard at lower speeds. Also it kind of seems to follow the transmission gear shifts – like it’ll get a little louder as the revolutions increase and then drop and get softer as the car shifts to a higher gear, then get louder as the revolutions increase again.

-There is no residue or sign of oil at least on the inside of the radiator cap. I have not been able to find the oil dipstick for sure. EHow says this about its location –
On most models, it’s on the driver’s side of the engine compartment parallel to the oil fill cap and valve cover. It has a yellow colored ring handle and “engine oil” is stamped on the ring.
But I did not see anything yellow. There was a black plastic thing that vaguely looked like a syringe top that I was able to pull out that had an H and L stamped on the dipstick end, and I’m assuming this is the oil dipstick, but it looks nothing like any other dipstick I’ve seen. And, the stick was only about ¾” long so not too much oil/whatever it is on it to look at. Looks like oil and no radiator fluid traces on it. Although oil was changed recently.

-When I turn the key in the ignition to start the car there is now a weird pause where there is no noise at all before the car starts to run. I don’t know why this is but it can’t be a good thing.

funkdaddy's avatar

> What kind of car is it? This will help with everything.

> If it seems to be related to the transmission, is it an automatic or manual? Does your speedometer work correctly? Do you have a tachometer?

> The reservoir you found sounds more like power steering or brake fluid, not oil. Althought ¾ of an inch still sounds really short for either.

If it’s a modern 4 cylinder car, the dipstick will probably be up front, sometimes they snake through the exhaust manifold, most of mine haven’t been colored any particular color that I can recall. They all have had some sort of loop at the top and been between a foot and three feet long.

Others could be slightly different, but they’re usually pretty easy to check.

Easiest way to find yours is probably just to go to google, type in ”<make> dipstick location” and then click “images”... someone probably has an image of your engine bay with a nice arrow pointing right to it. Civic example

prioritymail's avatar


> Mazda Miata MX 5 1992.

> Auto. Speedo works. Tach works.

> Right? I know where the brake fluid is so it’s not that. Never dealt w/ power steering fluid so I guess it could be that. I know exactly what you’re describing, as all my previous cars have had the same, but I am not seeing it under my hood. I am gonna look again later today. I kind of wonder if it looks different since I’ve also never seen the trunk and gas cap release in a plastic compartment between the seats. I am gonna try the images…great idea!

funkdaddy's avatar

It looks like it’s exactly where you described, by the firewall on the driver’s side. It may not be yellow anymore after 20 years ;)

dipstick and closeup

You might want to just go ahead and swap the transmission fluid, check the old fluid for metal shavings.

Also there’s tons of miata forums that would probably be great resources (not pushing you away from here) Each car tends to have it’s own quirks so there may be a common failure that your situation describes perfectly.

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