FordExcursions.com Forums
Keith Ruff
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• Manahawkin, NJ, USA |
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• Registered on 8/30/2004 |
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• 41 posts |
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 Posted:6/8/2007 14:10 |
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I posted a message about engine vibration but I think I confused several readers. I thought I had a driveline vibration at 75 mph, but it turns out it is related to the engine somehow. For those of you with the 6.8L motor, do me a favor and check this out for me. Start your Ex, leave it in park, and rev your motor up to about 2500 rpms +- a few hundred rpm's and tell me if you get a harmonic cycling noise. This is not a vibration per se, but you can hear the motor have a cycling wa, wa, wa, wa.......that seems to be at it's worst in my Ex at 2500 RPM's. I can actually feel it in the floor as well as hear it. This is the exact noise/feeling I get when cruising on the highway at 75mph, which equates to 2500rpm's on my Ex. This harmonic noise/feeling has nothing to do with the driveline as it happens while in park while revving the motor. My mechanic friend has a customer with a 6.8L Ex who also has this exact harmonic noise/feeling, we are wondering if this is a common problem with the 6.8L motor or an inherant harmonic for the V10 motor.
Appreciate any info if your Ex has this same harmonic or if you know what causes this noise. |
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monsta
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• The Big Island, HI, USA |
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• Registered on 1/5/2002 |
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• 1,056 posts |
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Posted:6/16/2007 15:49 |
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I'll go try mine today and report back. 
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monsta
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• The Big Island, HI, USA |
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• Registered on 1/5/2002 |
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• 1,056 posts |
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Posted:6/18/2007 02:14 |
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I don't get any of the noises like you describe. There must be something loose somewhere making that noise or it could be ... aw heck ... I don't know. 
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Keith Ruff
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• Manahawkin, NJ, USA |
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• Registered on 8/30/2004 |
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• 41 posts |
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Posted:7/9/2007 07:16 |
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My mechanic friend finally spoke with a 35 year Ford veteran about the harmonic vibe at 2500 RPM's in park. Turns out that this was fairly common on Excursions, they don't know why it didn't effect other Ford trucks, but there were several complaints about this on Excursions, but not enought to warrant a recall or "Free" repair (of course). The culprit, the Torque Converter. So now I am thinking I will either live with the vibe, as annoying as it is at 70-75 mph, or figure out how to scrape up the dollars to replace it. Is this an issue of potential damage to the trans or just a annoyance? If I replace the TC, what would y'all recommend as a replacement, OEM or aftermarket? How much am I looking at? |
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dwdixon
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• gaston, NC, USA |
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• Registered on 6/2/2007 |
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• 9 posts |
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Posted:7/15/2007 07:09 |
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I've had the same problem, felt the vibration in the floor at 70+ mph. I was going to try to live with it as annoying as it is, but last night around 80 mph I could tell there was a serious prolem somewhere, also beginning to feel it at lower speeds. Knock on wood, the engine seems to run flawless, trans shifts perfectly. Guess it'll go to the shop in the morning. When I find out what is I'll post it.
David
2000 Limited 4X4 V10 |
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Keith Ruff
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• Manahawkin, NJ, USA |
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• Registered on 8/30/2004 |
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• 41 posts |
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Posted:8/14/2007 10:40 |
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I thought I had the vibration licked yesterday but I didn't. We replaced my alternator as preventative maintenenance, had 87K on the original so I figured it was near the end of it's life. Installed a new alternator and noticed the 2500rpm vibe that was felt when revving the motor in park was now nearly gone. We took the old alternator and hooked up an air gun to it to spin it and could feel a harmonic clunking - I think the bearings may have been on their way out and that was causing the 2500rpm vibe. Figured that was the fix, but low and behold at 70-75 I still have that vibration that can be felt in the floor with a some humming that can be heard. So now the 2500 rpm harmonic is gone but the 70-75mph vibe is still there. I've got around $4000 in recent bills on this Exc fixing worn out parts and chasing this vibe and still am not yet done. Just spent another $400 on 2 new Michelin tires and still have to find the source of the vibe. I have replaced the Constant Velocity joint, balanced the driveshaft, high speed balanced all of the wheels, replaced the rear rotors with new OEM as well as pads front and rear, cut the front slotted rotors, replaced upper and lower ball joints, end links, hubs, and lubed the yoke. I have not tried the 3-5 degree spacers to better align the driveshaft but my mechanic doesn't think that will make a difference since it is so slight. I am thinking perhaps the wheel bearings are going bad? I have heard of pinion gears being suspect, but I've only got 87K on this Ex and I have heard these are built to last 300K miles. Trans shifts smooth and engine pulls strong, so the vibe seems to be caused by something that is turning at 70-75mph, I'm running out of ideas and things to check......  |
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Keith Ruff
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• Manahawkin, NJ, USA |
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• Registered on 8/30/2004 |
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• 41 posts |
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Posted:8/20/2007 09:35 |
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A little bit of an update. My mechanic jacked up the Ex and ran the speed up to 70mph, checked every wheel for noise/bad wheel bearings and they were perfect. While it was jacked up, he checked the rear and front axles for noise, they were also perfect. He is convinced that the harmonic vibe is not driveline relate but is either engine or trans related, most likely either the harmonic balancer or torque converter. We are going to try the HB 1st and see what happens, any other ideas are greatly appreciated. |
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monsta
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• The Big Island, HI, USA |
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• Registered on 1/5/2002 |
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• 1,056 posts |
• 2
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Posted:8/20/2007 14:17 |
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Not sure how the harmonic balancer could be the culprit since it only happens at road speed. Even if the TC were the culprit you shoulda heard it when he jacked it up.
Was 4WD engaged during this "test"?
I would suspect the needle or unit bearings up front but I'm not sure if that is the direction you are hearing the noise.
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Keith Ruff
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• Manahawkin, NJ, USA |
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• Registered on 8/30/2004 |
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• 41 posts |
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Posted:8/20/2007 18:00 |
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Noise is not only while driving, it also happens when you rev the motor while in park. My mechanic had his assistant hold the tensioner so the belt would not spin while he revved the motor to 2500 RPM's, noise was still there so he weeded out the rest of the pulleys, then jacked up the truck and set the cruise to 70-75mph which is 2500 RPM's and checked the drivetrain - no noise coming from wheel bearings, axles or driveshaft, so he suspects the HB since the harmonic comes and goes at 1500, 2500, and 3500 rpms. |
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