Weird Noise When I Turn Off My Car

[tjmach]

there is a weird noise when i turn off my car 1996 LS 400 130,000 miles. it comes from the motor area, and it's a weird pulsating sound. it's hard to describe: it's not constant, its like a pulse and it gets slower the longer the car sits. like a short hum sound. any ideas what it could be? thanks for your help!

tj

[chilkoot]

that is weird. how long does it take to go away and how loud is it? most cars make a "tink-tink-tink"ing as they cool that gets slower over time, pulsating like you said. However, it's nothing like a hum, they're short and fast little ticks.

[aggiecarpenter]

My 96 with 85,000 miles does the exact same thing. I posted this exact same problem a couple of months ago. Someone told me it was the rad cap so I replaced it. I didn't hear the noise for a week or so, and then it started again. Its an intermittent moaning sound that starts when I turn the car off and slows down until it stops. It sounds to me like it is coming from the radiator. I would love to know the cause of this as well. Its embarrassing when I get out of my nice car in a parking lot and it starts to moan!

[tjmach]

that is weird. how long does it take to go away and how loud is it? most cars make a "tink-tink-tink"ing as they cool that gets slower over time, pulsating like you said. However, it's nothing like a hum, they're short and fast little ticks.

it takes about 4-5 minutes to completely subside. i know the tink-tink-tink sound you're describing, but it is not that at all. it's kind of dull sounding, and you have to really listen to be able to pinpoint it. however it is audible. i hope it's nothing serious, i just bought the vehicle.

thanks,

tj

[tjmach]

My 96 with 85,000 miles does the exact same thing. I posted this exact same problem a couple of months ago. Someone told me it was the rad cap so I replaced it. I didn't hear the noise for a week or so, and then it started again. Its an intermittent moaning sound that starts when I turn the car off and slows down until it stops. It sounds to me like it is coming from the radiator. I would love to know the cause of this as well. Its embarrassing when I get out of my nice car in a parking lot and it starts to moan!

you know, it sounds like it's coming directly from the center of the motor (where the carb would go if it were an older car). it's barely audible with the hood closed, but you can kinda hear it. i just noticed it this past weekend. i hope it's nothing expensive! i just bought it!!

thanks,

tj

[chilkoot]

...my old Taurus made a noise after shutdown because of a bad seam between the coolant tank and its lid, it was a pinhole leak that I never really lost any fluid through, but the release of pressure made noise.

tighten down your water filler housing bolt, see if that helps.

[oslo]

Its embarrassing when I get out of my nice car in a parking lot and it starts to moan!

I lol'd.

[landar]

that is weird. how long does it take to go away and how loud is it? most cars make a "tink-tink-tink"ing as they cool that gets slower over time, pulsating like you said. However, it's nothing like a hum, they're short and fast little ticks.

it takes about 4-5 minutes to completely subside. i know the tink-tink-tink sound you're describing, but it is not that at all. it's kind of dull sounding, and you have to really listen to be able to pinpoint it. however it is audible. i hope it's nothing serious, i just bought the vehicle.

thanks,

tj

Noises can drive one crazy when trying to pinpoint. So, how about trying an experiment? This has worked for me on several ocassions.....get a stethoscope like the kind used to monitor blood pressure(you can buy these pretty cheaply at a drug store), only take the diaphram off the end of the hose and replace it with a large nail(spike). Then when the car is making the noise, carefully listen thru the stethoscope by positioning the point of the nail on various areas of the engine. The noise will be much more pronouced when you get near the source. While not perfect, this may give you a better clue as to the source.

Also wonder if it isnt some slight boilover of the radiator fluid indicating that your thermostat needs replacing and/or cooling system flush and refill. Anyway, let us know what you find.

[nc211]

radiator cap.... change it. seal is bad, sound coming from system depressurizing itself after car is turned off. it happens....... no biggie...

[aggiecarpenter]

radiator cap.... change it. seal is bad, sound coming from system depressurizing itself after car is turned off. it happens....... no biggie...

Its not the radiator cap. I have the same issue with my 96 and the rad cap did nothing.

[nc211]

yours might not of, but his might, as this is usually a common solution to sounds like this. plus, it's a cheap part, and why not start with the cheapest and go from there? do as you wish, but a bad seal seat of a radiator cap can make this happen too...

[aggiecarpenter]

yours might not of, but his might, as this is usually a common solution to sounds like this. plus, it's a cheap part, and why not start with the cheapest and go from there? do as you wish, but a bad seal seat of a radiator cap can make this happen too...

I agree with you. The rad cap could make this noise, but he said that the noise was coming from the middle of the engine compartment.

[dcfish]

there is a weird noise when i turn off my car 1996 LS 400 130,000 miles. it comes from the motor area, and it's a weird pulsating sound. it's hard to describe: it's not constant, its like a pulse and it gets slower the longer the car sits. like a short hum sound. any ideas what it could be? thanks for your help!

tj

When was the last time the rad fluid was changed ? And what was put in at what ratio to water ? Does the car run hot ? Is there fluid in the rad overflow ? Was the thermostat changed ? Have you changed your oil lately ? Did you seafoam the crankcase ?