Hi guys
Well I’ve been chasing down a vibration in my truck (99 f150 5.4 2wd) for about a year now. At first I thought it was road speed related, but since have found out that it is related to engine speed as it will do it with the truck in drive, park and neutral. At idle I have a slight shake, at 1000rpm it is a low rumble, at 2000 rpm its kind of a pulsing buzz, and at 3000 rpm higher frequency of the 2k rpm sound. Its felt through the whole truck. I have done fuel filter, new cops, been through all vacuum lines, (its never had a check engine light on and I’ve scanned and there is no codes) I’ve been to two ford dealers and three independent guys. One dealer said maybe the torque converter but he didn’t think so, due it it driving ok. The other dealer said they could mount a dampener under the bumper and it might make a difference. I didn’t do either. In the last couple months I’ve noticed that every blue moon my starter will grind, no big deal just turn it again and it will pop right off. But that got me thinking, so I pulled the inspection plate off the flexplate and there is about a 2 or 3 inch span of damaged teeth… almost like the starter didn’t disengage and just wore them away. I was just wondering if you guys would think this could cause the vibration. I know that fly wheels are really heavy and if out of balance could cause some real shaking, but I’ve never dealt with a flex plate… not really sure what the difference is other than one is for automatic and one for manual… I’d really appreciate your input. I tried to attach a photo of the damaged teeth but the forum says I'm not allowed to post attachments.
Thanks in advance

 

If the vibration damper on the crankshaft is in good shape, I would say that has a 90% chance of being the problem. Consider how small wheel weights are, and if a wheel is out if balance it can vibrate like crazy.

 

Thanks for the reply. Thats kind of the same thought I had too. I know losing one of those small wheel weights can really make it shake. So what exactly causes the teeth on the flexplate to get damaged? Is it a bad starter? Anyone else ran into this?

 

...bump...