I have an 89 f150 300efi m5od
My truck is making a funny noise. When you press on the peddle about half way if makes a grinding/cladering noise for a little bit then goes a way. I pulled our 12' trailer with a lawen mower on it and it made the noise the hold time I pulled it. I pulled the same trailer with 4500lbs of sand and it never made the noise. It doesn't do it under light or heavy acceleration. It just does it under moderate acceleration and under load ( excepted when I hauled the sand). I know its hard to say what it is without hearing it but what would cause something like that? Its coming form under the hood. I just hear it at in the cab when I'm going down the road. It doesn't make the sound just idleing or if you slowly rev it up at idle.

Any ideas? I tryed to get a sound clip but you cant hear it. I will try with a better camera.

Any help is appreciated.
Thanks, Hunt

 

Oil pump? My thought would be to check the oil pressure. Does it only happen while you're moving? What type of transmission do you have? Maybe a pressure plate or something happening with the clutch if it's a manual. More details =-).

 

i have the same noise and same symptoms on my 78 300.i hope someone can help more.

 

Mine turned out to be the throw out bearing was going bad. If you push the clutch in a little way, and it quits, it is likely the same thing going on. On the 78 truck, you can get in there with a grease gun and hit the fitting on it. Don't put in too much, it will sling back out, and on the clutch The newer truch is a sealed for life unit,and can't be greased, so it will eventually need to be replaced