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67 GTO has underhood noise

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Jul 22, 2008, 11:48 AM

Post #1 of 3 (2229 views)
67 GTO has underhood noise Sign In

I am the original owner of a classic 1967 GTO. It has a 400 engine with a factory 2bbl carb. No A/C. Recently, it developed an intermittent flapping or dull grinding sound from under the hood. I thought it might be wheel bearings or spindle damage. All checked out OK. I replaced the old water pump since it seemed to wobble slightly on its shaft. After removing it, I discovered that the bearings were really noisy and I thought I had found the source of my problem. Not so. The water pump did not make a difference as the noise continued. The noise is evident on straightaways even at slow speeds. It does not get louder with more speed or rpms. It is not a constant sound but comes briefly and then goes away. I checked the alternator at a parts place and it checked out fine. I am running out of things to check that have bearings that might be causing the noise. The only item left that is belt driven is the power steering pump. It is the original pump and the car has 121,000 miles. Could I check it by removing the ps belt and driving the car with unassisted steering? Would I hurt anything by doing this? If the noise is not evident, then it must be the ps pump. Any other suggestions to determine the location of the sound or defective part? Needless to say, this car has been meticulously maintained.

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DanD profile image

Jul 23, 2008, 4:18 AM

Post #2 of 3 (2223 views)
Re: 67 GTO has underhood noise Sign In

For a short road test; removing the belt will not do any harm. I would maybe lower the fluid level in the reservoir, by a couple of inches. Turning the steering without the pump running may force the fluid out of the steering box and in turn cause the reservoir to overflow.


Canadian "EH"


Jul 26, 2008, 10:30 AM

Post #3 of 3 (2205 views)
Re: 67 GTO has underhood noise Sign In

timing chain slop? if never changed it could concievably be loose/worn enought to intermittently slap the cover and sound like grinding. quick check by getting hold of the crank pully and moving backward and forward. you will feel the chain begin to engage the cam if you do this gently enough. more than 5-8degrees play indicates a bad chain/gears....more than 10-15degrees will cause slap.
another odd thing you might try is to rotate your tires front to rear - same side. i've seen this happen many, many times.

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