Driveline Harmonic
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Driveline Harmonic
All.
I own a 1996 F250 with a 7.3 PSD. I've noticed a humming sound coming through the floor when the trucks at about 1500-2000 RPM. The trucks actual speed and whether it's in 4WD or not makes no difference. After checking the TSB's on this site I discovered one that describes the problem exactly. The reccomended fix is to replace the motor mounts, transmission mounts and the front catalytic converter mount. That all sounds like it's going to be really expensive. Has anyone dealt with this issue before? How did they get it resolved?
I own a 1996 F250 with a 7.3 PSD. I've noticed a humming sound coming through the floor when the trucks at about 1500-2000 RPM. The trucks actual speed and whether it's in 4WD or not makes no difference. After checking the TSB's on this site I discovered one that describes the problem exactly. The reccomended fix is to replace the motor mounts, transmission mounts and the front catalytic converter mount. That all sounds like it's going to be really expensive. Has anyone dealt with this issue before? How did they get it resolved?
Playing in the Dirt
Joined: Oct 2005
Posts: 2,302
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From: Southwest Georgia
Just a WAG here but, it sounds like "down pipe hitting firewall syndrome" or something close. Ford loves to throw parts at problems. I find it hard to believe that the motor mounts, transmission mounts and the front catalytic converter mount would all go bad at once. There are alot of trucks out there still running all of the stock mounts with no problems. I would look into this further before throwing parts at an unknown problem and hoping that it helps. Just my .02.
Senior User
Joined: Nov 2007
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From: taunton , ma
co131 welcome to the FTE I agree with PLOWHAND check your exhaust even if the mounts were gone they would make noise all the time. try rotates your tires and give it a whirl Mine gets this humming noise too and if I rotate the tires every 5 months I don ' t get any noise. Its weird but try it!
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Tuned
Joined: Mar 2006
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From: PNW
Originally Posted by CO131
Thanks guys. I'll take a look when it woarms up a bit. We were at -46 yesterday morning.
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Elder User
Joined: Nov 2005
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From: Cincinnati OH
you stated an rpm range. does this happen when the truck is not rolling. if it does, then we know that it's in the engine. the reason i ask is because you said that different speeds dont make a change.
if the engine's ruled out...
i agree with the tire rotation. tire balance too.
check the carrier bearing
get the wheels off the ground and spin all of them and see what you find ie wheel bearings, diff gears, etc.
if the engine's ruled out...
i agree with the tire rotation. tire balance too.
check the carrier bearing
get the wheels off the ground and spin all of them and see what you find ie wheel bearings, diff gears, etc.
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I live in Central Alberta right in th mountains.
I've already addressed the tire issue by putting 4 new ones one.
The noise doesn't happen when the truck is stopped - only when moving.
What is a carrier bearing and how do I check it?
I've already addressed the tire issue by putting 4 new ones one.
The noise doesn't happen when the truck is stopped - only when moving.
What is a carrier bearing and how do I check it?
Elder User
Joined: Nov 2005
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From: Cincinnati OH
don't ask for spec/numbers. if it's real bad a visual inspection will show. grab the prop shaft near the carrier and push/pull up/down. some play is ok, but if it flops around in there like a straw in a glass then it needs to be replaced. i hope someone else can give some more detail.
did this by chance start when you put the new tires on?
did this by chance start when you put the new tires on?
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I check the driveline bearing and it seems fine. I checked the exhaust coming from the manifold and It looks like there's no contact with the firewall. It's really close though. I heard a rumor that the engine may twist slightly (torque related) when it's under lad and this may put the down pipe and firewall in contact. Does this make any sense? What's the next thing I should be doing?