Strange Vibration

If it's the original motor, I'd check the harmonic balancer. It consists of two pieces(inner and outer)with volcanized rubber attaching them together. Over time the rubber lets go and usually just slips, but sometimes the outer piece will let go and could cause major damage.

You wrote "sounds" like a dull vibration. Vibration doesn't make sound. Insufficient info to make any sort of guess. Mick is correct about old balancers. This could also be the sign of a valve head getting ready to pop off the stem.

George

I am thinking ignition problems....maybe fouled plug or bad wire. take a look under the dist cap....... One thing you can do is remove one plug wire at a time while the car is running. If you remove one and it does not change the idle..then that may be the failed cylender. You may want to wear a thick glove that is shock prof, because the voltage is quite high, anyway if it shocks you youll know the fire is getting there.

I agree its the balancer or a Valve ... find the problem before driving the car .. unless you plan to pull that motor ....

KARLC,

Did you find the problem?

I haven't had time to get at the engine yet. checked wires and plugs. all seem ok. Had to go away on business for 4 days. Hoping it is just the Balancer, replace that so I can use it for the summer. Then I want to pull the engine, and have it rebuilt. only 47,000 miles on it. runs strong
replace gas tank, had 1 leak. Still love it though.

There was someone on the De Tomaso BB that had a vibration under load. One of the recommendations (by Jack DeRyke) was to check the bolts on the half shafts. Turns out this was the problem. Most of the bolts were loose.

I noticed I hear the vibration more in 1st, 2nd and 3rd gears. not so noticeable in 4th or 5th
But I also hear it slightly at a stand still.
pullys look good, belts ok. check timing tonight.
I have a new Harmonic Bal. for the next step.
thanks for the help.

The "hearing" vibration thing has me perplexed as to exactly what we are dealing with.

Please check your exhaust header bolts where they attach to your cylinder heads.

Your friend on the DTBB

I don't know if this could be your problem... Maybe the motor mounts have given up over time and have cause the exhaust to hit the chassis somewhere. I'm assuming that this vibration occurs when the car is stationary and or going down the road. The only two things come to mind would be exhaust or balancer. Keep us updated

While engine running, pulled off plug wire 8, no change in engine, put back, tried 7, same. tried #5, same. pulled out Pcv, no change. It still sounds to me like timing is off. or detonation is not right. I'm just a weekend Mechanic, so it may take me some time. but I don't give up easly.

AttaBoy, karlc, Do'nt let 'em get you! Tell us a bit more about your ignition...MSD? What distributor? My car gave me fits with poping and skipping, I changed everything,wires cap, nothing helped UNTIL I replaced the plugs and gapped them at .050 for the MSD box, and it has not missed a lick yet. Once a plug gets wet fouled, they should be replaced. I would at least pull a couple and look at them. A mis will cause a vibration.

KARLC,

2 things come to mind that you can check ??

1. The balancer ..take the engine cover off and inpsect it... is the rubber in the middle of the outer ring there ?? does it look like the outer ring has rotated ??

2. take off the valve covers and see if all the keepers on the valves are there and the valve stem potrudes about a 1/4" above the keeper ... any broken valve springs ??? LOOK CLOSE.

3. this is a long shot .. but I purchased 2 cars .. and both have similarities. I bought a 68 427 corvette that had a 454 flywheel on it and a 66 428 cj that had a 427 flywheel on it. Both were mix matched with internal and external flywheel balancing.

how did I get the same problem twice in my life ?? LOL

Ron

Ron

Troubleshooting like this is very very frustrating. However, if removing a spark plug wire from 3 different cylinders did not make the engine run slower & rougher, that is significant.

Something is amiss. I reason if the timing had slipped, the motor wouldn't run at all, or would buck very badly. So I'm guessing the spark is very weak.

If it were me, my next step would be to check the voltage to the ignition system with the engine running, pull a plug and inspect the electrode (I would expect to find a black & wet plug)and finally run the engine with a plug removed and grounded so I could see the spark (it should be fat & blue).

your friend on the DTBB

If the outer ring of the balancer spun it would make a vibration and the car would run ?? He said he had it 10 years so flywheel is out.

yeah Ron, it would run & vibrate. BUT Karl pulled plug wires off with no drop in engine speed or rougher idle. If this is so, the motor is running pretty poorly. The motor will maintain its state of tune if the balancer spins, it will just be out of balance, and yes in that circumstance it will omit a hum, I've heard it before. but what we have here is a motor running so poorly that pulling a plug wire makes no difference. If it were a slipped timing chain, it wouldn't run at all. So what does that leave us?

What we know is the problem occured during a long drive, it was running ok at the beginning of the drive, but was "vibrating" at the end of the drive. No changes had been made to the motor.

come on guys, whadda ya think?

THanks Guys. I checked the Harmonic Balancer, looks good. rubber intact, Timing around 13 TDC I replaced the plugs Used Autolite AP25, gap 35. I have a Ford Electronic ignition system that I purchased from Hall Pantera about 8 yrs ago. came with Module, distributer coil etc. Car has plenty of power, if I get into it, it goes no hesitation. no skips. engine mounts are ok. Noise seems loudest in 1st, 2nd & 3rd gears, around 22-2400 rpms. mostly in 2nd gear. had car out for 1/2 hour, 65 mph in 5th. smooth and clean. but I do hear something in background.

Maybe the timing chain skipped a tooth. How many miles are on the engine? Cam timing could cause this problem.

quote:

come on guys, whadda ya think?

Just a hunch, but have you been to Disneyland lately?

Many times that humming sound is just in your head. It comes whenever you take the "It's A Small World" ride. That song is almost impossible to get it out off your head and many times people hum it unconsciously, thinking the resultant sound is coming from the engine, computer, toaster oven, whatever. The good news is, I don't believe it has ever damaged a Cleveland engine.

BTW, this hum is not to be confused with Dynamo Hum. That's a totally different hum.

Whadda ya think?

Jeff
6559

So the Hum is when your driving and not standing still .... its the ring gear bolts are broken or loose ??? if its driving when it occurs .. thats my take.

JEFF that was not the answer we were looking for. LOL

OK Karl....

If the noise/vibration is only heard/felt when the car is moving, you'll need to foucus on the parts that only rotate when the car is moving such as wheel bearings, half shafts, squirrel cage, etc.

But that still doesn't explain why removing a plug wire didn't affect the motor.

Its a small world after all ........

Leaky exaust manifold maybe? Or header gasket. I know a small exaust leak can make some really wierd sounds.

Noise is there standing still or moving. around 22-2400 rpms, especially in 2nd gear. George, I
pulled plug from #8, started car, grounded plug. I see a white jagged spark, not blue or fat. Car runs smooth, no noticable noise in 4th or 5th. no skips, and it flys if I get into it in 1st gear.
I didn't hear any difference when I pull the plug wire, but I didn't look at tach. will make sure tonight. Hot as hell out here 98 yesterday.
Maybe the Coil has gone bad!!

I watched the Tack when I pulled off the spark wire. it does drop about 200 rpm.