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302 vibrations at 2000 rpm

Just got this truck (89, F150, 5 speed overdrive). In all the gears it has a pretty rough vibration at 2000 rpm. It's very narrow, and can be accelerated through (but it's right at 65 mph in 5th). Based on feel alone, I'd probably tend to shift a little later (2500 or so), but that vibe is forcing me to shift earlier. The owner's manual lists speeds to shift at, but they seem REALLY low. Is this a known issue, or should I be looking for causes. Any neat tricks to move it up to about 3000 or so?

Also, I can't find a factory manual for it (am in the process of tracking down a "Chilton's book of lies" to use until I can find a real manual). The AC cycles about every 8 seconds in defrost. I'm guessing that's normal/intended? I can feel it in the cab, and notice it if I'm driving real slow (out of driveway in first). Guessing I shouldn't feel the surge? Idle is a little rough, and seems slow (500 or so on dash tach, haven't measured accurately or looked under hood for correct number)

Thanks,

Bob

Reply to
Bob Fourney
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The vibration may be something in the driveline. I once shed a balance weight on a rear drum. I'd never feel the vibration except at about 62-63mph on the freeway and then it would go away. Once I had the weight brazed back on, the problem went away.

Could be an out of balance tire/wheel, drivehshaft, sticking U-joint etc. crawl under, over and around it and see if anything is obviously loose or tweaked.

Shift points are up to you. Shift as high or low RPM as you want. You're going to need to correct that vibration tho..

Can't help ya here. E-bay always seems to have factory service CDs available.. Might help.

Reply to
The OTHER Kevin in San Diego

if, after youve checked the obvious things and it still persists, check the pinion nut. its a common problem where it backs off a bit and causes some vibration. when replacing, replace the pinion seal also! hope this helps ya...

Reply to
BattleGodz

everyone missed the point. He has an RPM vibration, NOT a speed specific vibe. It's something in the engine. I'd look closely at the fan, then the harmonic balancer, then the clutch disk. Will it do it at 2000 in neutral?? What about with the clutch pushed in?

Reply to
Steve Barker

Bob,

I had a engine vibration like that on a truck of mine and it ended up being a bad cooling fan clutch. If your ford has a clutch fan, see if it has any play/whobble in it.

Bob

Reply to
Bob Wilsey

Thanks Steve and Bob,

I'll check the fan and the clutch. I haven't tried revving it up in neutral yet. As I push the clutch in to shift at 2k it continues to vibrate as it idles down through 2, so I suspect it'll do it w/ the clutch in also.

I'm guessing this is not "normal" (they all gotta vibrate as some rpm, right?). I saw a bunch of posts from 302 F150s with vibrations at 65 mph and was guessing that the auto tranny might just shift before 2000 until high, and then they see it at 65 mph (happens to be

2000 rpm on my 5 speed OD transmission).

I'll let you know what I find out,

Thanks,

Bob

Reply to
Bob Fourney

Hi Bob, If I grab the fan, I can move it out of the plane (away from vertical) about 20 degrees. That is, I can move the tip of the top blade back over an inch. I'm assuming that this is not normal? I think my ranger has a similar fan/clutch, I'll try to wiggle that one tonight. The movement seems to be between the shaft and the clutch? Hopefully this is it (I like it when the problems are on the outside of the engine).

Bob

Reply to
Bob Fourney

Bob You need to park that puppy until you can change the fan clutch. That thing is about to come apart, and it won't be much fun.

Texas Parts Guy

Reply to
Rex B

I can't swear that is your vibration problem, but it is a start. The clutch style fans I have dealt with were on a old Chevy pu with a 350. I have seen

2 go bad and both cause a rumble-like vibration passing through certain rpm range. The clutch assy. will have a little movement, but if you grab the top and rock it front to back and oh shi#$%t comes out of your mouth it needs replacement. If that fan lets loose it is real bad news.

Bob

Reply to
Bob Wilsey

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