302 Engine Noise

[Hg80Design]

My problem is I have a 302 that is making a tapping noise on the front of the engine. It almost seems to becoming from the water pump / drivers side front of the head area. The noise is loudest at startup and seems to keep pace with the engine when revving it up a bit. After it runs a bit it becomes fairly quiet but still there.

I have replaced the Waterpump with an edelbrock, as well as installed a new alternator, I also thought this might be an issue with a valve in the drivers side head. I went ahead and removed the valve cover and bumped the engine. Everything appears to be working properly. I also put in new plugs and checked the oil in the heads for any metal flakes. Plan on changing the oil this weekend and cutting open the oil filter to make sure there is nothing in it as well. What I did notice through this was that a few of my header bolts had begun to back out. I tightened them back in place but the noise is still present.


Any help or ideas would be greatly appreciated.

 

[68conv4sp]

Check your timing chain. I just pulled mine off to change the heads and found that it was very worn.

 

[Fast63]

your fuel pump could be bad, and the arm making noise. However, if your headers bolts backed out, the gasket might have been damaged and re-tightening the bolts would not help that unless they are copper gaskets. Check for exhaust leaks at the header.

 

[Hg80Design]

Thanks for the ideas will go ahead and replace the header gaskets. Will take a look at the timing chain this weekend. I appreciate your help. The fuel pump is relatively new, about 6 months old. I tried getting a sound clip of this but all you can hear is the fan.

 

[D.Hearne]

It can also be what used to be called "fuel pump knock" or front main bearing knock. The Motor repair manual said the main bearing knock is caused by too much timing advance at idle. Usually caused by connecting the dist advance hose to full mainfold vaccum, or excessive main bearing clearance.

 

[Hg80Design]

An update 3/20/08 - I replaced the header gaskets and installed some new header-bolts while I was at it. I also loosened the Alternator belt just a smidge, thinking it might be overly tight. Neither of these seemed to be the issue.

Jacked the front of the car up and checked the Harmonic balancer to see if the little rubber ring in it had slipped out and was making noise. This also does not seem to be the problem. The balancer appears to be good shape.

Next, I removed the belt to try and isolate the noise. No luck here either there is to much draw on my electrical system to be able to fire the car without a belt. It dies pretty fast ( as in before I can even make it to the engine bay to listen).

So, I pulled out a long flat head and began using it as a mechanics Stethoscope. It appears the noise can be heard in the fuel pump area as well as dead center of the deep part of the oil pan. This is not a loud noise, its barely audible with the hood closed. It can be heard from the top as well as the bottom of the engine.

Anyone have any suggestions on how to isolate it further? I am leaning towards a bad fuel pump and or oil pump but want to confirm this exactly before I go on a parts replacing spree.

 

[VTStang66]

You need 2 things. First is a length of hose, garden hose or heater hose. Several feet. Cup your hand around one end and hold it to your ear, use the other end to probe around and see if you can pinpoint the noise. This works well for noises on the outside of the engine, like exhaust leaks.

I also have a stethoscope type thing I got at advance auto I think. It was pretty cheap. Not like a doctor's stethoscope with a diaphragm to go on skin, but this one has a black plastic piece around the diaphragm and an aluminum rod sticking out. You touch the rod to the engine, like valve covers, fuel pump, etc., and it works very well for finding noises inside. Noises like that can be frustrating, just keep looking, you'll figure it out. Good luck.

*edit*
I just reread your post, guess you already have the mechanic's scope idea down. Sounds like you might want to invest in a battery though. You could try spinning the water pump and alternator by hand with the belt off.

 

[Hg80Design]

Thanks for the idea about the hose for ambient noises will give that a try ad see if I can pinpoint it further. The screwdriver seems to work good for hearing internal noises tough.