Hi,

I bought a 1998 F150 with a 4.2 engine (109,000 Kilometers) back in March 2009. At the time of purchase, I was concerned about the leaking lower intake manifold gasket issue, so I verified that the engine was built after 15 January 1998.

For the first month or so, there have been no motor issues, but for the last several weeks, I've noticed that the motor has started to knock or clatter. The knocking always occurs when I first start the engine, and then will go away after a few minutes. If I drive it for longer periods, the sound comes and goes. For instance, if I coast along for a while, and then accelerate, the knocking sound returns. Or if I start the engine when it's warm, the knocking sound returns.

Yesterday, I drove the truck for 15 minutes and it knocked the whole way. 4 hours later I started the truck. It clattered for a minute until I revved the engine and then it stopped. I then drove it for another 15 minutes knock-free. I then stopped the engine and started it up 10 minutes later and drove it for another 10 minutes. It knocked the whole way. This is what I mean by intermittent.

I'm about to take the car to my local garage, but I'd like to get a heads up from this forum on what the problem may be. Hopefully it's something that can be easily fixed.

Thanks in advance for your feedback.

 

This is my best guess....sounds as if there is an Oil delivery/pressure issue. Perhaps low level? sometimes sticking oil pump check valve? partially clogged oil pickup? Sticking liftters?

If this is truly a Knock, as in bottom end rod knock, really you should not drive the vehicle untill you know what is happening, otherwise you could be on your way to a replace or rebuild expense.

lets us all know the outcome,

Knowledge is power

 

I know I'm a little late to the game on this one, but it sure does sound like an oil pressure/delivery problem.

Did you get it figured out?
Or does it still knock?
Or did it break?