Vacuum leak noise aroud the throttle body only on idle

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Vacuum leak noise aroud the throttle body only on idle

Postby st185_cs » Thu Sep 10, 2015 9:30 pm

Hello.

My st185 CS has been in the garage for about 6 months because of a faulty alternator and engine wire harness.

I fixed this during the weekend, but now i have another problem after i assembled the car again.

There is a noise simillar to a vacuum leak around the throttle body/intake manifold. The car makes only this noise at idle. If pull the throttle cable a bit, the noise disappears. The engine runs ok, but when it warms the idle goes too low and the engine almost stalls.

i have checked all the vacuum hoses and everything appears to be ok. The noise comes out from the area next to the throttle cable end. I dont know if this noise is normal or not.

any help? will upload a video as soon as possible.
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Re: Vacuum leak noise aroud the throttle body only on idle

Postby alltracman78 » Thu Sep 10, 2015 10:06 pm

Leak at the throttle plate shaft seal?
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Re: Vacuum leak noise aroud the throttle body only on idle

Postby masco » Fri Sep 11, 2015 2:42 pm

Sometimes after sitting the idle valve (ISV ISCV IACV whatever you want to call it) can get stuck or sticky. So the change in sound/idle characteristics is likely due to that. I suggest cleaning it out with your favorite cleaner product and see if you can get it to free up. In my experience clean ST185's sound like they have a vacuum leak at idle, which is just that valve opening up to do its job.

If you still suspect you have have a vacuum leak try spraying a brake cleaner or some cleaner product around the source of the sound at idle. If you hear the idle speed change (generally rises) then you have found your leak.
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Re: Vacuum leak noise aroud the throttle body only on idle

Postby Gibs » Sat Oct 31, 2015 7:57 am

Going to try that. My ST185 has been sitting for 4 years now and now that it is running I also have a whistle sound. Going to try to clean the ISV. Thanks
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