Sound from under valve cover???
 

Ok, I know this could be a million things but here gos. You can here a whistling sound under my hood and it seems to be coming from under my passenger side valve covers. When I put the handle end if a screwdriver to my ear and stick the other end of the driver to the valve cover right over the #1 cylinder, you can hear it pretty loud. Anybody had this happen oe have any idea what it could be. I just started hearing it about a month ago after switching to a synthetic blend but the car still runs great. ?????????????

Could it be related to the PCV valve? It might cause a whistling sound on the passenger side valve cover. That's where mine is connected. If it didn't shut completely off at idle, it might whistle a little. Take it out and squirt some carb cleaner through it and see if that helps. A new one is only a few bucks. Just a thought.

Rev

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'66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph
1/4 mi.

Has to be the PCV. Only thing that I know can whistle. Take Rev's advice, go by a new one, they're cheap.

Mine was doing that and it tturned out to be a loose bolt on my carb.

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66 Mustang Black W/ Black
289 Hi-Po 65'heads, MSD
Lunati High lift Cam
750CFM Carb Heddman Headers

Replaced the PCV valve. Still no luck. I guess I should mention it's not a constant sound. It's the same pattern as like a lifter tick would be but this is a howling or whistling sound at the same time interval as a lifter tick. Could it be something with one of the rockers. I've never heard anything like this before. But it's definitely coming from under the valve cover.

A small exhaust leak at the header/manifold gasket has the same timed interval as a rocker and might also produce the whistle sound. Just a thought. Hope you find the problem .

Lou

Could it be valve guides leaking past the valve stem/seal? My header leaks always sound like a lifter (click, click,click) or (piff, piff, piff). Just another possibility.

Rev

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'66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph
1/4 mi.

I had a whistle that would start after my motor warmed up. Turned out it was a warped metering plate on my carb. I swapped it for a metering block and the whistle stopped.

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65 convertible
289 Hi Po
4 speed

Hey David, pull the cover and take a look. Then lay some towels just below the cover and start it up and check again. This will help narrow down where it is exactly coming from. If you want use a long piece of tubing like the screwdriver technique and you will find it.

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69 351W Sportsroof deluxe