Ok so I just picked up this 1989 F250 351 4x4 the other day. Drove the truck over an hour home, and I didn't have any issues with it. However the engine seems to be making a noise which I'm quite unsure of what it is. To me it honestly sounds like a knock. The truck doesn't make the noise at idle only when given some throttle. Just did an oil change on it, and the oil didn't have any shavings etc in it. Also have ran it since I put the new oil in it and it's still clean nothing in it. Really hoping the engines not shot as it honestly runs great aside from this noise. Any help would be greatly appreciated thank you. Also here's a video so you can hear exactly what I'm hearing. Thanks!

https://www.youtube.com/watch?v=SsWU...ature=youtu.be

 

Sounds like a rod knocking to me.

 

Sounds like a rod knock, hard to tell. Rattles on the decel. You could try to pull plug wire one at a time at idle. See if it changes tone or disappears. Could pinpoint what cylinder. All I got with what hath given.

\/\/ I agree with this next guy

 

2nd that sounds like a rod knocking meaning loose or bad rod bearing. What weight oil did you use? If you used thinner oil than 10 W 40 that could be part of your problem .What kind of oil pressure do you have? low oil pressure would make engine knock. How many miles on engine? .If high milage use thicker oil 10w 40 or 15w 40. If thicker oil does not help oil pressure or knock problem time for new bearings and oil pump.

 

Used 10w 40 when I changed the oil. The oil pressure gauge was 3/4 of the way when I drove it home, but now since I've had it in the driveway whenever I start it it's about 1/4 of the way maybe a little more it seems a bit low to me. The truck only has 24k on it, was used as a plow truck. Is it possible that it's the oil pump causing the low oil pressure thus causing the knock?

 

Shes probably rolled the odo over once or twice. Clogged oil pump pickup is more likely than pump. Or bearings as stated earlier with rods out of round being the worst case scenario.

 

Odo hasn't rolled the mileage is correct. Was a plow truck for a hospital the past 25yrs, and my uncle worked there. Just seems bizarre to me because aside from the noise the truck runs amazing.

 

Could be carbon on top of a piston.

 

Try taking the belt off and idle it. See if the noise goes away. Just be aware you will have no water pump. Dont run it long. < disclaimer