Need help identifying an ?engine? noise..

[stouchton]

Folks - need to help isolating a possible engine noise.

Sounds like tapping a piece of sheet metal with a hammer (gently). It is intermittent, kind of comes and goes.

Sounds like it is coming from front of engine, loudest when you listen directly in front of radiator.

I removed fan belt and it stopped.

Water pump seems fine, fan is tight and there is no side play in end bearing. In/out play is about .010". Bearings feel fine.

Generator does not have any play, though the rear bearing has a squeak and it cannot be lubricated externally - heard it using a stethoscope.

Crank pulley is tight and runs true.

In fact all pulleys run true.

Only suspicious thing I noticed is that I needed to slightly lift motor to slip v belt back over crank pulley - guess my front mount springs have sagged slightly.

After putting the v belt back on the sound went away for a while (couple minutes), then reappeared.

Can not isolate it with stethoscope - but definitely sounds like tapping on sheet metal with hammer. Not continuous tapping, but an intermittent tapping: tap tap pause pause pause tap pause pause tap tap tap pause pause pause pause tap ......

Anyone have any clues??

Thanks,

Scott

[Big hammer]

Um.... so you raised the front of the motor to remove the belt and the noise stopped?
Then you put the belt back on and the noise started? I would check out the front motor mount springs. Hope this helps.

[SeaSlugs]

Originally Posted by Big hammer

Um.... so you raised the front of the motor to remove the belt and the noise stopped?
Then you put the belt back on and the noise started? I would check out the front motor mount springs. Hope this helps.

have you installed a new pulley? Maybe its hitting the crossmember. I've heard the internal oil pan baffle come loose and had intermittent hammer on tin noise before.

Is your fan loose on the shaft? Maybe its wobbilying and hitting the radiator. If its an original maybe its cracked. How tight is your belt? How far does the generator move over to apply tension? It could be lightly vibrating into the lower water neck.

[Tom Wesenberg]

Can you move the crank pulley back and forth before the crankshaft rotates?

Fan belts can chirp or squeak, but the tapping might be a loos crank pulley.

Is the rear of the generator a bearing or bushing?
Either way, it should have an oil hole, as does the front bearing.

[lindy williams]

Regarding the generator squeak: the brushes can make a slight squeaking sound when rubbing on the commutator. This is normal.

[BILL WILLIAMSON]

Sponsored Links (Register now to hide all advertisements)

Spray a little Windex or water on the belt & see if it stops. "Maybe" a new belt is in order???
"Maybe" clean the belt & pulleys with Acetone will help???
Bill Guessing

[captndan]

Check the front motor mount. You may have to add a washer or two.

[stouchton]

A little more info:

I have made no changes to the engine except to change the needle and seat in the carb.

Fan is tight, does not wobble at all.

Originally the fan belt was tight, however when I put the belt back on I kept things on the slightly loose side (about 3/4" deflection).

Generator looks like it has a rear bushing. There are no oilers on my generator. I was going to simply disassemble and oil. Maybe it is the brushes, but the generator was restored in 85 and not touched since so i figured the bearings/bushings were due for oiling

I did grab the crank pulley when the belt was off and tried to move it - it had no play at all - in/out and trying to rotate back and forth.

Hoping to take a closer look tonight - will post back anything I find. I do appreciate your thoughts on the issue.

Also - I do have a spare belt, so I can do a belt swap. The belt on it looks brand new however.

[Greg Jones]

Check engine pans. They can cause all kinds of horrific noises if loose.

[SeaSlugs]

Originally Posted by Greg Jones

Check engine pans. They can cause all kinds of horrific noises if loose.

those too, and accelerator brackets to firewall make some interesting noises.

[stouchton]

I wanted to thank all of you or the suggestions.

At the moment the sound has ceased. Had a friend come over last night, we cracked open a couple beers and let the car run for half an hour. His only comment was about the bearing squeak! (I was wrong, it has a rear roller bearing but it cannot be lubricated externally). The mystery noise never returned. Right now I hope that means it is nothing serious.

I am going to check your suggestions just to see if I spot something. I am also going to oil that generator bearing and order a new one.

[Tony Hillyard]

Perhaps a couple more beers is the answer!

[Tom Wesenberg]

Are you sure you don't have a hole to oil the ball bearing?
Here are 3 pictures of different rear generator ball bearing end plates, and you can see the oil holes are covered by a metal strap that needs to be pushed to the side.

If you have the bearing out, then a dab of grease will last for years.

[stouchton]

Tom - front bearing retainer has an oiler hole. Rear bearing retainer does not.

Picture shows my bearing - and I thought it was self destructed until I saw your picture...

[Dave in MN]

I rebuilt my pickup engine about 25 years ago with a local company doing the Babbitt work. After about 2500 miles, the center main went out. The Babbitt was not bonded to the block. There were black carbon spots behind the loose Babbitt about 1/4" in diameter. I then sent the engine down to Herman Konke and had the mains re-done. I then drove it for about 2,000 miles and had the same noise crop up again. I assumed I lost the center main again.

I was so disgusted that I pulled the battery and did not drive it or pull it out of storage for 18 months. When I started to work on it, I started it up and removed the belt as part of tracing the sound. The noise went away completely. Something in the long generator was making a low frequency noise like a center main. I replaced it with a powerhouse rebuilt by Tom Wesenberg.

Herman's work was good and still is to this day.

It is easy to jump to conclusions before fully checking the system over. From this experience, I always remove the belt when I am tracing engine noises.

Good Day!

[Tom Wesenberg]

Originally Posted by stouchton

Tom - front bearing retainer has an oiler hole. Rear bearing retainer does not.

Picture shows my bearing - and I thought it was self destructed until I saw your picture...

The space with the bumps in the metal should contain a felt ring, which retains oil and keeps dirt out. You can cut a thick felt or a couple rings of thin felt to fill the space. Clean and grease the rear ball bearing, install the felt, and you should be set for many years.