I have a 97 f150 4.6 with 91000 on it. It has always had a knocking noise for a couple of seconds when I start it up on a cold day. Recently the noise has been constant even after warm up. I have changed the oil every 3000 miles. I was wondering if using a thicker oil or an oil additive would help quiet the noise. I think stp or luccas would thicken the oil but I thought I would ask if anyone has had this problem. Any advise would be great.

Thanks
Budman

 

Not wise to thicken the oil. You need oil to the heads as quick as possible. You sure it's not an exhaust manifold leaking?

 

I'm not sure. The noise is definitly coming from the drivers side of the engine. It sounds like someone is hitting the block with a heavy object. I think if it was a rod bearing the sound would be coming from the bottom and would be just as load on the passanger side. I will listen again and see if maybe its an exhaust leak. Thanks for the reply.
I did read a thread on another forum that the owner had this problem and added marvels mistery oil and the problem went away. I may try this. marvels would thin the oil. Any more ideas out there ?

Budman

 

Try using a Motorcraft brand oil filter. It has a very good anti-drain back valve that keeps the valvetrain lubricated @ startup.