sharkthehunter77

It sounds like when a kid puts a playing card in the spokes of a bicycle. I feel its coming from the fan but the fan seems just fine...wierd! I have checked the tension on the belts, they seem fine ( they are fairly new). The pulley in front of my power steering pump moves just the slightest bit when shes running. Any ideas ?

78Vette-SA

Had the same or similar problem. Was the fan hitting the shroud. It was just touching enough to be annoying. Was in a hard to see spot to.

Might want to check it.

BigJoe55

I also had this problem, and it was the fan hitting the shroud and one day when I hit the gas hard I got just enough movement to catch a good chunk of the shroud and tear it apart. Get it checked out and you may just need to trim the shroud and in many casses you can just remove the shroud if you do not have any cooling problems! Good Luck :iagree:

BSeery

A car I had once made a noise at the water pump. The studs that held the fan and pulley to the water pump were screwed in too far and were hitting the water pump casing.

BUGGSY1970

Check the fan shroud. It will look shiny or worn where the fan hits.

Make sure the shroud is mounted correctly. Check the attaching bolts on the bottom. If they are not comming thru the appropriate holes in the shroud it throws the whole symetry off.

77Dream

Sounds like the perfect excuse for a new electric fan. :yesnod: :D

Stoge

Not to flame BigJoe55, but I do not reccommend removing your fan shroud. Our cars are not the easiest to keep cool, especially in summer, even more so if you do a lot of stop and start driving.

Check your motor mounts, fan shroud mount bolts, make sure your fan shroud is seated in the radiator support correctly, and check your fuel pump. It could be a bad belt also.

The Dude

Another thing to think about is something under your timing cover, maybe? It's a long shot, but did you just install a roller cam?

The reason I ask is that I did a stupid thing the first time I installed a roller. Instead of setting the endplay for the cam button by dimpling the timing cover, I ground material off the back of the cam button. Anyhow, that "slop" between the back of the button and the front of the cam let the button slide back and forth between the cam and the lock plate when the engine was running. It would make a loud intermittant tapping noise.

Turbo-Jet

I once had a snapping sound coming from the front of the engine, but I could not narrow it down. I concluded it must be the fan clutch, as it was shot anyway, but eventually discovered it was the main V-belt. The belt had a few cracks on the inside that would randomly 'snap' due to natural vibration as it came around the smaller pulley. Check the entire belt for cracks, as it could be this simple.

GaryS

Like some of the other comments, I would suggest that the fan is hitting the shroud. Helped a friend install his 454 in his 73 and we put the fan blade on backward. :crazy: It would only touch the shroud during acceleration because the engine would torque just enough to allow the blade to touch.
Gary

jackson

It could also be a worn out timing chain slapping around inside the timing cover. Pull some belts off & listen if the noise goes away or not.

Alwyn678

Fan could be hitting the shroud due to a brken engine mount and the motor is lurching a bit

BSeery

:iagree:

MasterDave

Sheesh, just take the fan belt(s) off and fire it up. If the sound is gone you can at least eliminate the engine as the culprit. :thumbs:

cardo0

Master Daves technique should eleminate the fan/shroud, belts & pulleys.
It does sound like the classic shroud VS fan contest which maybe caused by broken motor mount (happened on mine).
Another trick is to use a steathiscope - sold most auto parts stores ~$15. Keep the rod out of the rotating fan & belts (Dah!) and listen to water pump then timing cover or what ever turns you on. If your shark is close to 100K miles its due for at least a new water pump and likely the timing set also. :yesnod:

Captain Morgan

MasterDave gives some good advice. I would also join the crowd that it's possible the fan hitting the shroud. Have you pulled the shroud for any work recently? I had pulled mine to work on the radiator and haven't been able to get the shroud aligned right since. Every once in awhile it will move on me, and I have to loosen the bolts, move the shroud, then tighten the bolts again. My fan was hitting at the bottom, and would get worse with acceleration. It's most likely the fan. Good luck, I don't think it's a big problem.

Crash Dummy

Have you done anything as simple as someone else in the vette revving it up and you doing the observing to see if you can pinpoint it?

On that note.... the stock blade with clutch assembly is pretty stout compared to aftermarket stuff. Can I possibly expect the same problems(if that is the problem) as I dumped that whole assembly for a Perma-cool turbo 17" flex fan with a spacer to replace it? And I am planning on winging a few more RPM's(5000-5800) than those shrouds were not probably designed for.