Tapping/knocking sound
New User
Joined: Dec 2001
Posts: 5
Likes: 0
Tapping/knocking sound
For background I have a 1979 F-250 with a 351M.
I notice this somewhat at an idle but more so upon acceleration.There is a tapping/knocking sound which while driving sounds like it is coming from behind the steering wheel,close to the left hand side of the engine.Other signs of problems that I notice is smoke coming from the exhaust during idle speed.Ironicaly the truck isn't using oil.
I tend to think the worst,like an engine that is probably close to being shot.One thing that puzzles me however, is that when putting the truck in neutral and reving the engine,the sound may stay the same but with higher acceleration tends to disapate (or perhaps is drownded out).
Any help or insight would greatly be appreciated.
I notice this somewhat at an idle but more so upon acceleration.There is a tapping/knocking sound which while driving sounds like it is coming from behind the steering wheel,close to the left hand side of the engine.Other signs of problems that I notice is smoke coming from the exhaust during idle speed.Ironicaly the truck isn't using oil.
I tend to think the worst,like an engine that is probably close to being shot.One thing that puzzles me however, is that when putting the truck in neutral and reving the engine,the sound may stay the same but with higher acceleration tends to disapate (or perhaps is drownded out).
Any help or insight would greatly be appreciated.
Junior User
Joined: Apr 2000
Posts: 77
Likes: 1
Tapping/knocking sound
You should be able to smell and see the difference in burning oil or your motor just running rich or not tuned. As far as the noise under the hood it sounds like valves to me. What kind of oil pressure do you have. At idle of course your oil pressure is at it's lowest and that is why you have more noise. You have excessive clearance somewhere.
New User
Joined: Dec 2001
Posts: 5
Likes: 0
Tapping/knocking sound
Thanks for the reply Steve....
Just to add a little more.This morning on a cold start the noise is still there.There was no smoke coming from the exhaust either,although I didn't finish letting it warm up.The oil pressure is in the normal range,on the Low/High gauge,sitting at about the 10 o'clock angle.And actually I don't have more noise at an idle,the noise increases as you give it gas.Like I said it seems to disapate when you give it a lot of gas,but since it returns I suspect that could be just the engine noise drowning the clciking sound out.
About the valves....If this is the case is this a sure trip to the shop?Any chance any of the "over the counter" additives could help.
Just to add a little more.This morning on a cold start the noise is still there.There was no smoke coming from the exhaust either,although I didn't finish letting it warm up.The oil pressure is in the normal range,on the Low/High gauge,sitting at about the 10 o'clock angle.And actually I don't have more noise at an idle,the noise increases as you give it gas.Like I said it seems to disapate when you give it a lot of gas,but since it returns I suspect that could be just the engine noise drowning the clciking sound out.
About the valves....If this is the case is this a sure trip to the shop?Any chance any of the "over the counter" additives could help.
