Well we got the truck with 30,000 on it now it has about 3X,XXX on my 4.6 Regular Cab. Ever since we got it, it has had the slightest, lightest engine knock. I mean you can BARELY hear this but I can so It drives me insane. Im almost 100% sure its an engine knock. It runs fine just that, I was thinking about adding octane booster or 91 fuel and see what happens but I dont know yet, help?

 

Sure its not an exhaust leak? You can check for a rod knock by disconnecting one injector at a time and listen for the noise to stop or lessen when the suspect cyl is disconnected. Get an inexpensive mechanics stethescope and by placing the probe on different areas of the engine you should be able to find its source. Could be a chain tensioner as well. Harbor Freight sells a stethescope for around $6.00.

 

It could be, I cant pin point the area. I have noticed it some times will go away for about 15 seconds then come back in then fade back out.

 

could be spark knock mostly caused by bad gas, or if you have a programer a tune with too much timing. now i'm not callin you a lire but to me from the way you describe it, it doesn't sound like engine knock cause trust me you will know engine knock. it could also be injectors i have and 03 4.6l and mine are quite noisy.

 

So are you saying I shouldn't worry about it. It just seems to run too smooth for a knock.

 

Please describe under what exact conditions it knocks.

 

i'm not saying ignore it, i'm just saying that the way you describe it, it doesn't sound like knock TO ME. when i think of knock i think of rod knock which sounds like knock on a wooden table, when i think of spark knock or ping which sounds like a ping, or a short ringing noise, and when i think of tick it sounds like a tick, tick, tick of a clock. now does it sound like any of these, also like GLC asked what are the conditions that it becomes noticeable. hope this helps.

 

could it be a fram oil filter??????

 

It does it in series, like every a couple times in a row then stop for the same amount of time then a couple knocks. Its only on the passenger side, its very light knock enough that you can hear it inside but step a couple feet away then you cant hear it. Motor runs smooth, and you cant hear it in the exhaust.

 

as dynotech said might be an exhaust leak? but you say it's definitely a knocking sound like knocking on a door. it might also be the tensioner pulley bearing is wearing out but that might be more of a tick, look into to it.

 

Well im going to run octane booster through it and see if that helps than go from there. Its not a tick its a knock but from where? I know its from the passnger side.

 

You still haven't addressed the CONDITIONS........

Idle in Park? Idle in gear? Low RPM's? High RPM's? Light load? Decelerating? WOT? Low speeds? Highway speeds? Illegal speeds?

Is this a bit clearer?

Higher octane will NOT HELP ONE BIT if it's not spark knock. This only happens under load.

 

All low RPMS, under load, not under load. Once under normal throttle it goes away.

 

Then it's not spark knock.

 

Hey guys i have a 97 f150 with a 4.6. my engine knocks only when accelerating/or climbing hills normal driving on flat roads its goes away. any ideas what it could be?