i own o1 dak 4.7 thought it was spark knock at first cause got louder under load constant with rpms. then i noticed it was from under the engine listened around with stethoscope couldnt find it. in idle you can hear this knock. give it a little gas in park it goese away till rpms come back down. sounds loudest near passenger front tire. gets real loud up hill. been going on for 2 months now. did the seafoam, plugs, nice new oil mobil 1. a few months ago had to change campostion sensor. it broke of in engine pulled oil pan and retrived. and thats all i got need help.

 

Is it coming from the top of the engine or bottom of the engine?

Sounds like it could be a bearing knock.
Oh, check the flex plate. Could be cracked. A cracked flex plate sounds just like a rod knock.

 

its from the bottem couldnt find it with a stethoscope

 

Do you lose oil pressure at idle?
Based on what you said, sound like a rod knock or a bad flex plate. The flex plate is cheaper to replace then a rod, obviously. If you can't do the work yourself take it to a shop.

 

yes i i do lose oil pressure idle i never thought of it. why do u ask if its rod knock im screwed ive alot problems with this truck they just keep piling on good learning.

 

Well, your experiencing a knock in the bottom engine. I asked if your losing oil pressure at idle because if you have a spun bearing, one of the major symptoms is a loss in oil pressure at idle that comes back when you push the throttle.

Sounds to me it is indeed a bad rod or main bearing.

 

i checked my flex plate looks all good. i was tooling around with the sthethoscope, maybe a slight tick in first bank,but the knock is crearly heard in passenger wheel wel. the knock will go away after a few minutes or maybe just quiter. if rev a little bit the noise comes back when idles down stays for a few secs then gets much lass noisy. gonna take 1st banks valve cover off see if i i can find anything. im still pretty clueless. weres the key points i should be listening into with the scope

 

If the knock is in the bottom engine, removing the valve cover probably isn't gonna tell you much. You'd better off dropping the oil pan and looking for metal shavings. Have someone spin the engine over my HAND (DO NOT USE THE STARTER!!), in fact, disconnect the battery before you do anything.

So ya, take off the oil pan and check the bearings. Looking for any metal shavings. When you turn the engine over check the bearing (If you can) and see if you can find the culprit. On the cylinder walls look for any scoring or knicks.
If you have a spun bearing, there will most likely be metal shavings in the oil, in the pan or on the magnet in the pan.

 

thanks for all the info im gonna drop the pan and see but i have rain for the next for days so im gonna have to wait just would like to say thank u for all your help you hear from my in a couple of days

 

We've got rain here for the weekend as well. Where bouts in Mass are ya? I'm in Albany NY