Horrible Noise from engine

Help! I previously described my noise as a "chirp", but it's more like a "sqeal". It sounds like a metal-on-metal rubbing noise. I took the fan belt off and it didn't make a difference. Tried the stethescope method (using a metal rod pressed to various locations on the engine and held to my head) and everything sounds like its running a sewing machine. Where could it be coming from? I've checked all over the top half of the engine, the alternator, water pump, and distributor. I even went over to the exhaust side and checked around over there.

Could it be something around/inside the timing cover? Bad camshaft bearings? I really don't want to pull the engine again!

Finally, I should mention: it doesn't make the noise until the engine is considerably warmed up. And when it makes the noise, it generally is loudest at idle and seems to go away when I apply light pressure to the throttle. Then when I let off the gas, it's back.

I need to know where to look next!

--Jonathan

Are you sure it is not the alternator? Sounds like something that happened to me when I installed a new one several years ago. It was the fan blades hitting the housing. A little bending of the blades, and no more noise.

Get a can of carb ceaner amd check for intake leaks. They can sound like that.

I had this issue last month. I had to tighten the bolts holding the intake on. A zero cost fix for a change.

Larry

Well, you checked everything I would suggest. Are you sure it isn't the exhaust system? When it's making the noise, push hard on the exhaust with your foot in various places along the pipe. That's an odd one allright!

Just out of curiosity, how is your oil pressure and level? If either is low, do NOT drive that car!

You could very well be onto something there Larry, that's the first thing I thought of too. A vacuum leak could be causing the gasket, or a piece of it, to vibrate like the reed in a saxophone.

Wow, excellent idea. I'll check it tomorrow night and let you know. I put the sounding pipe on the bottom of the header and didn't get anything, but I'll try the shove it and listen method too.

So no one thinks I've got a bad main cam or something expensive???

Knowing that it is a simple minded thought, how about the fan belt? Have you checked it for looseness? The sound not appearing until after warm-up suggests otherwise, but the sound is similar to that from a slipping belt?

Jim D

If it's what Larry and I are thinking it will be an intake leak.

Yes, like Larry and JDW said. I had a leaky carb throttle shaft and it screamed like a banshee sometimes at idle.

Just another idea...if it's only happening at warm up when idling, maybe it's something in the cooling fan(s)? If you have a '66, you probably don't have electric fans, but i've heard that on the late model cars the fans make a death yelp right before they die. The earlier cars may be different...but it's just a thought.

Jonathan,

Wondering if you found the source of the noise? I discovered what sounds to be the same thing on my 79 B...

Jeff

Check out any rotating shaft. Some rely on oilite or other self lubed bearings and can "go dry" and squeal like hell. In other cases, oil starvation from the central oil system or another source of lube can result in metal to metal contact resulting in the shrill squeal. Do check out the air/exhaust leak theory too. Note if its pitch changes as speed/vacuum/pressure increases.

Hi Bob,

Thanks for your input, I'll follow your suggestions.

Here are the specifics:

The shrill noise doesn't start until the engine is well warmed up (oil psi & temp are good).

It sounds like a waterpump or air pump bearing, but seems to be from the rear of the engine, as best as I can tell.

It is present at idle, and goes away when the RPM is increased by about 500, then comes back, louder.

It is loudness seems to follow the engine's RPM - clutch in/out doesn't change it, speed doesn't change it.

When cruising along on a level road at a steady speed, the sound is at it's least, except initally during acceleration.

I do have a small leak at the speedometer cable / transmission 90 degree piece, and a smaller leak at the drain plug.

When I come to a stop, the sound continues for about 1 minute and then goes away.

Please advise if this additional info is meaningful.

Thanks,

Jeff Chambers

PS - I moved down here to San Diego from Twin Falls. My daugher is currently attending BSU... Small world, huh?

Distributor shaft!!!

if it is coming from the rear, a possible cause could be the pilot bearing for the first shaft of the transmission. Even if the car is not moving, and the shaft still, the engine continues to rotate the pilot bearing (in the rear of the crank) around it. The pilot bearings are oil impregnated sleeve bearings and if the lube has dried up or it was never been well lubed (adding some lithium grease upon installation doesn't hurt and adds a measure of security against a dry bearing), it can run dry and it can squeal like a stuck pig ~ sometimes almost continuously, sometimes intermittently and sometimes only when the clutch is used.

Take your stethoscope and place it as close to the rear of the block casting and you should be able to hear a similar noise to what you hear otherwise. Sometimes you will hear a somewhat different noise there, altho a metal on metal noise of a different pitch than when it squeals. Normally, there should be a sound smoothly moving parts, anything else should raise your suspicions.

Bob - when the clutch is released, the gearbox input shaft is rotating the same speed as the crankshaft so the pilot bearing should not be making any noise. Unless the clutch is slipping - and then it is a whole different story!

I guess that is right, Eric, I forgot it would be in neutral. I forget sometimes. Been too long, I can tell, since I had to work on one. I do know tho that a pilot bushing will chirp or squeal sometimes. Oh, well.

LOL - I hear ya! It's funny but I have often heard that the pilot bearing can make a noise - but I can't say that I have ever heard it! Perhaps I don't use the clutch often enough! ;)