mystery vibration.

[Ren]

'67 F250, 352, cruiseomatic.

When I bought this truck a few years ago, there were lotsa little things wrong with it involving virtually every major and minor operating system. Most of these problems were due to age, neglect, and lack of common sense.

Over time, one by one, I've solved the vast majority of these problems by scouring the archives of this forum, asking questions, scratching my head, buying parts, and getting dirty. I'm not a 'gearhead' or mechanic by any means, but I've managed to muddle my way through everything so far. And I've learned alot in the process.

Except for an engine vibration from 1200-1400 rpm. It happens when the truck is moving. Uphill, downhill, on level ground. It happens standing absolutely still. It happens in P, R, N, D, 2 and 1. It does not lose power, stutter, fart, smoke, or make strange noises. Just vibrates. Nothing alarming. Only enough to be noticeable to the point that I seriously doubt it left the factory that way.

Otherwise, the engine is very responsive and runs very smooth and quiet throughout the rpm range. And I believe it has all the power it should have for 208 hp lugging around 5000 lbs of weight.

I've looked for broken or cracked engine mounts and missing hardware. I've poked and prodded. Nothing is jumping out at me.

Could it be the harmonic balancer? It appears to be a genuine Ford part. It has two sheaves. One sheave appears to be integral to the balancer and powers the water pump and alternator. The bolt on sheave operates the water pump and power steering. The power steering option is not original and was added by a po twenty plus years ago.

[cep62]

Have you ever tried taking the belts off ?
it'll rule out the fan and other accessories , just don't run too long without the water pump turning.

[Ren]

No. That thought didn't cross my mind. Thanks.

[Ren]

It was the harmonic balancer. Had it rebuilt by Damper Doctor in Redding, Calif. Vibrations were reduced significantly.
Cost $94 to rebuild. Round trip 1000 miles UPS Ground, $35.
Sent it on a Monday, had it back Wednesday next week.

The timing marks lined up exactly where I left them.
They painted it with a black finish that came up with my thumbnail. No big whoop. Unless yer a whiner.

The reason I went this route was that my balancer has an integral sheave milled into it in addition to a bolt on sheave. All the pics I saw online for replacements did NOT show an integral sheave, and are made in China. Inquiries online to vendors regarding the sheave issue produced nebulous answers. Some people will tell you anything if it's what they think you wanna hear.

[colnago]

Wow! I just went to Summit to look at harmonic balancers. Ka-ching! They were all over 300 bucks! Yeowza! Now I'm not sure what to do for my re uild.

Joseph

[Ren]

There are cheaper, new balancers to be had for less than what I paid to have mine rebuilt and shipped. And I probably would've bought one if the people selling them could hire representatives that know what a 'sheave' is. And the made in China issue, although not a deal breaker, was a turnoff as well. I have a good friend with a lathe and the notion of having a sheave cut into whatever I bought crossed my mind as well.

[Ranchero50]

That's cool that you figured it out. What did they do? Just replace the rubber or does it have extra machining marks where the removed metal to balance it?

[Ren]

The rubber is definitely new. I didn't notice any new machining marks.