Strangest Intermittent Noise Ever

'57 Fairlane
HO302/AOD


Just completed the engine/****** swap about two months. I am getting the weirdest buzzing sound while driving. Here's the details:
1. Happens only after initial startup when everything is still somewhat cool in the engine.
2. Speeds up and slows down with RPM's.
3. Sounds almost like when you would put a playing card in your bicycle spokes as a kid, but the cards would be made out of thin metal this time.
4. Stops after about 3 or 4 miles (sometimes less) of driving.
5. Only does it again in the same day of the car sits for several hours.

It sounds like it's in the area of the bell housing/flexplate, but noises tend to carry in this car. I checked the torque converter nuts and they are tight. It's almost impossible to troubleshoot because it only does it while driving and it stops after a couple of minutes.

- Maybe the starter gear isn't pulling back far enough at initial startup?
- Maybe the spacer plate between the engine/****** is buzzing on something, but why would it only do it when cold?

I'm stumped. The car is running great, but I can't help but think that this could mean something is going to break soon. I sometimes subscribe to the theory that you just wait till it breaks, then you'll know what it was, but this seems to be timing itself perfectly to coincide with the Roundup!

I might even buy another mini-starter to keep in the trunk just in case that's what it is.

Any other theories?

 

Hydraulic lifter bleeding off pressure ??

 

did you put a cam in the motor? the reason im asking is the fact that after i put a cam in the cone that bolts to the cam that operates the fuel pump was rubbing the timing cover only when i drove it and it stopped after a few minutes. after it finally wore the spot down it quit. when i tore into the motor 5 years later there was a tiny spot polished on the cover. but no damage.

 

I've got a 400sbc/th400 in a truck that does the same thing and its done it for over a year with several different starters on it. I'll be interested to see if anyone can figure it out.

 

Lifters are brand new, so I doubt it's that...at least I hope not!

Now that I've had time to ponder, I'm leaning toward the starter. It's one of those "inexpensive" mini starters that are found on that auction site for $69. Maybe the gear isn't retracting right away. I may tap it with a hammer in the morning and see if that does it.

I'm still open to more theories!

 

It's the stock roller cam. It's not the original timing cover, though, because the one that was on there was pitted. Could be...

 

Could it be a fan blade hitting when the engine rocks over under load? Does it do it sitting still, in gear with a little engine rpm? Exhaust leak? If the valve covers are on backwards the rockers can hit (don't ask me how I know). Fuel pumps can tick. Cracked flywheel. One last thing, a loose piston. If you pull one plug wire at a time you may be able to isolate it to one cylinder.
Jeff

 

One more. Torque convertors on some of the Fords liked to balloon too. Then they end up taking the thrust out. It may be heat sensitive. You would just need to make sure the torque convertor will slide back away from the flywheel.
Jeff

 

I'm betting it's at the torque converter (is it new?) the flywheel (is it cracked?) or the front pump of the trans (was it rebuilt?).

That starter drive kicks back over an inch.. I figure if it was touching at all, it would be obvious as it would grind pretty hard. Not a "card in the spokes" kind of noise.

 

Sounds to me like torque converter or possibly front pump issues. My 53 Merc sounds like that too and I am prepared for front pump or converter repairs.

Does the car engage quickly when put in D or R? If not it sounds like front pump "growl".

 

Did you have the oil pan off? This is really way out there, but I am just p***ing it along. I had that same noise in a mustang, while the pan was off the windage tray got bent and it was hitting the crank.
CHAZ

 

it's the torque converter. when they go, the make the old "card in the spokes" sound.

 

It engages quickly and shifts really smooth. I sure as hell hope it's not the pump or converter. The converter is brand new and I had the ****** rebuilt before I installed it.

It sure sounds like it's coming from that area, though. If it's the converter, would the sound go away after it gets warm?

 

Since it goes away after it warms up.. I'm betting on the front pump..

 

If that's the case would you call that a..."will eventually get worse and finally give out over time kind of deal" or a "this will probably break suddenly leave you on the side of the road on the way home from the Roundup kind of deal"?

 

Thatsa tough call... For the most part... If it is the front pump... It will talk to you for a while before it leaves you screwed... Check your fluid for metal..

 

I tend to lean toward the pump, but it usually is accompanied by delayed engagement. As things warm up the front pump tends to start to seal and the noise quiets down.

Don't overlook the converter though. One other thing is the lockup clutch in the converter, could that be causing some weird noise?

The noise (to me) sounds like marbles in the converter.

 

There's no glitter on the dipstick, but I may drop the pan just to check things out.

I think I liked this thread better when I thought it was the starter!

 

Try getting hold of a mechanic's stethascope. Run the engine and get under it while it's "faulting". If you try all the suspect areas you may be able to isolate the cause. I'm sure you won't, but don't just hope that it goes away.

 

It did it in Park at idle once so I started listening to different areas through my long torque wrench handle. I couldn't hear anything through the valve covers or the bell housing. Since that one time, it only seems to do it while driving or in gear, so it's hard to listen for it. I may put the rear end up on jack stands and see if I can get it to do it in gear while I listen. I completely obsess over random noises like this, so I'll stay on it until I figure it out...or until whatever it is, breaks.

 

i put my bet on the torque converter. the trans will act fine, shift fine and not slip. the noise will come and go until it gets ready to go for good. once it decides to go, the noise will be there all the time when i gear...it probably won't do it in park or neutral.
you may or may not find any signs in the pan when you drop it.
i am not a transmission expert, but i have lost converters in drag cars and daily drivers before. just because the converter is new, doesn't mean it isn't bad.
i may be wrong..but it sure sounds like a converter to me by the way you describe it.

 

Try having a friend sit in the car, with park brake on and stepping on the brake, trans in drive and reving the engine slightly so as to cause the noise. Don't overheat the ATF though. Also, a stethascope really works a lot better than any long solid object.

 

If the noise diminishes after it warms up,my guess would be something in the valve body is cycling rapidly.
My sons '67 Fairlane does it occasionally,(when it was driving),and it quit making noise when it warmed up.

Transmission guy said"don't sweat it",and the transmission gave no trouble.

It is immobile for wiring problems,(not transmission).

 

Dent in the sheet metal dust cover under the converter?

Contacts the flywheel starter ring when cold, goes away when warm.

When it happened to me I thought the metal would wear away, but it didn't.

Half hour job to pull it, hammer it out, bolt it on.

Cured the problem....

 

Could it really be this simple....

I started thinking about what has changed since the noise started. My old M/T valve covers were spewing oil everywhere because they don't have baffles on them. I installed some later model aluminum Mustang valve covers because they have big baffles and a long filler neck. I actually used two right side covers because the driver's side stock one is blank with no filler hole.

I decided to install a PCV system this time ,so I put a breather cap on one side and a Spectre PCV cap on the other (it looks like a breather, but has a PCV inside). That's around the time the noise started. Last night, I pulled the valve cover with the PCV cap on it and replaced it with the blank stock one. Started her up this morning and she ran great - no noises. I shook the PCV breather cap and it rattles like a can of spray paint.

Maybe it's rattling when the PCV is open and "loose" and then it eventually stops for some reason?

Funny someone also mentioned the sheet metal spacer between the engine and ******. The one I used wasn't in the greatest shape, but I cleaned it up and used it anyway. I was starting to think it had a dent in it causing the noise, too. If the noise starts up again, I'll check that. For now, I'm pinning it on that cheap *** Spectre PVC cap!

 

Take off the Spectre cap, plug the hose and see what happens.

Chase the simple stuff first, no use doing the Mondo jobs only to find a wrench rattling around on the intake manifold later....

 

Small Update....

It's definitely not the PCV cap. I ran without it for a few days and it still did it until it got warmed up. It seems to require shifting through the gears 2 or three times to get it to stop...which equates to the mile or two that it takes to stop.

It is incredibly difficult to troubleshoot because it only does it while driving. I actually stuck a stethoscope through the floor shifter hole so I could listen to the bell housing while the car is moving. It does SEEM to be in there, but it's hard to tell for sure. It's not the exhaust manifolds or lifters. I have ruled that out.

Another oddity of the noise. I've noticed that if I go over bumps in the road of any size while it's buzzing, it will get louder in proportion to the the duration and size of the "bounce". Does that make sense? That makes me think it's in the bell housing and hopefully just the spacer plate. The only thing that doesn't add up with that is that it stops after it warms up.

I should probably wait and see if it gets worse, but I think I'm going to pull the ****** after the Roundup. Something else I now recall from the engine install thrash week a few months ago. My buddy that helped with the install reminded me that the spacer I used was supposed to be for an AOD, but the starter opening did not line up with the mounting holes. I cut the section off for the starter hole and mounted it separately so the starter would be shimmed correctly. I'm now wondering (and betting) that the spacer (probably for a C4) is rattling at the point where I cut it off.

I picked up an AOD spacer plate the other night that was included with an old AOD that I bought. I'll swap that one in after I pull the ******. Now, I just have to decide if I want to put a new torque converter in while I have it out, just in case.


Any new thoughts/ideas based on this new info?

 

Something, exhaust pipe, trans cooler line, dipstick tube, touching the floor pan, or frame. When a little heat expands it, it clears. When the engine moves on the mounts when going over bumps, it hits harder.

You would be absolutly amazed at how much movement the engine/trans does do to inertia as the car does bumps.

Look for some shinny spots under there where something is rubbing.

Keep it simple!

Frank

 

+1.

 

Shot in the dark . . . got power steering?

My Ranger has a mild leak in the return line.
When it gets low, the power steering pump buzzes when cold, goes away when warm.

Got some line & clamps this morning so I can fix it tomorrow.