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Discussion Starter · #1 ·
Hi Diesel Stop,

I'm hoping you guys can help narrow down or put me in the right path. I have an annoying vibration in my 2003 F450 (7.3L PS, 6 speed, 2wd, 166K miles). It occurs in motion and not in motion, which leads me to believe its engine or clutch related. Just had the clutch, throw-out bearing, flywheel and pre-bled kit replaced by a good shop. The clutch was not worn out, but a crack was found in the transmission tail shaft housing. To replace, the shop pulled the trans, and for the extra money I wanted the clutch replaced. Vibration was there before and after the clutch work, with no noticeable change. Had U joints and carrier bearing replaced at the same time.

The vibration is most noticeable when cold. Its frequency is directly related to the throttle. When warmed up and driven for a while, its still there, but hardly noticeable at all.

No power loss, starts great, no smoke (cold or warm) ever. No CEL, and no codes on q ScanGauge II, but the X gauges are not hooked up yet. No mods other than a Superchips 1705 tow safe tune, but it did it before and after the tune as well.

I'm obsessed with the idea that it could be the harmonic balancer. I recently replaced one on a old GM 6.2, that really smoothed it out. But these are totally different animals. Are these ever an issue? It just seems to me that the rubber degrades over time on any balancer. But I'm no 7.3 expert, and I know I'd be disappointed it I spend $500 on a new Fluidamper, just to have the same old vibration at start-up.

Any thoughts?
Thanks,
Leo
 

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I just replaced my harmonic balancer on my 99. I could see that the rubber was poking out on one side and it was causing my belt pulley to move around a bunch. I can tell you it is a common enough problem that there is a nice write up on the fix somewhere on this site that I used. I just don't think it is your vibration problem. I would think that if it was so bad that you could feel it inside the truck, it would have thrown off or tore up your belt by now.

If it vibrates just sitting there, I would start looking at engine mounts or body mounts. Even exhaust hangers. A rock lodged between the frame and body would transfer sound into the body also.
 

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x2 on the harmonic balancer. Doubt it's your problem.
Start it up with the serp belt off to make sure it's not a belt driven item.
Could be an injector. You should have a contribution test run.
 

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Discussion Starter · #4 ·
Thanks guys, this is exactly what I needed to hear. The Fluidamper is about $450. Would have been a waste of money. I'll look into seeing if I can have a contribution test done on my truck from a local shop vs. biting the bullet and buying AE. I also really need to get the gauges in, as I'm curious to see what kind of fuel pressure is there.
 

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Depending on where you live, there are many members on the forum with AE.
 
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