i got a 90 4.9 and the last time i changed the oil after i started the truck and it had a slight knock at idle it comes and goes and its been about a month dont affect the driving of the truck but i took the serp belt off and started it n it was still there and it already has a new timing set. any ideas like i said comes and goes but only at idle some times its louder then others but not all the time i checked my fan shroud it aint that. plus truck only has 77k on it

we had a work van had same engine with 120k that knocked like a bitch now it has over 300k the guys ran it out of water 4 or 5 times warped the heads but she still starts and runs. so i know 4.9 are truely bullet proof

plus this is my 3rd 4.9 n i beat the hell out of my other 2 n never had a prob till this one

 

Do you have a Wix or Motorcraft filter installed? If not, change it out. Fram and the like are garbage on these motors.

Adrianspeeder

 

realy because ive used fram in all my trucks including my othe 4.9s and i put many miles on them in a short period of time n never had a problem with fram

 

The anti-drainback check valve on Fram is crap. Because it doesn't keep the oil in the engine for startup you get knocking.

 

well its not just start up it can be running for 30 mins n i come to an intersection as soon as i press the clutch and the rpm drops to idle it will do it. also i always have good oil pressure

 

It is your truck. Period. However I highly encourage you to try a better filter, and see if the problem goes away.

Adrianspeeder

 

i got a motorcraft filter and extra oil so when my truck cools down and it cools down out side ill swap them and get back to you

 

changed it still knocking but not as bad but i cant realy tell because it would come n go before

 

started it up this morning and again a few mins ago no knock guess u guys were right thanks for the help

 

Good thing you caught it before you had permanent damage - now do you see why we call Fram filters the "orange can of death"?

 

knock came back same as before just once and a wile just at idle