Diesel engine knock
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Diesel engine knock
I have a 2002 F250 7.3L diesel. I was driving my truck a week ago and the engine sarted to make a knocking noise while idling but goes away while driving. I checked the oil and it was three quarts low. don't know why it was low; never had that problem. (doesn't leak a drop) Thought it maybe a fuel injector so I tried some fuel injector cleaner but no change. any ideas?
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yes it still makes the noise after putting oil in and filling to the line.
Then I changed the oil, oil filter and air filter but it continues to make the noise; I was 7,000 between the oil changes and only 2,000 miles on fuel filter.
Then I changed the oil, oil filter and air filter but it continues to make the noise; I was 7,000 between the oil changes and only 2,000 miles on fuel filter.
Hook it, I'll pull it.
Joined: May 2007
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From: Grand Lake, La.
Is there any way you can get the codes read on your truck? If you can, give more info on the sound and when it does this. I know you said it only does this at idle, but try to give more info if you can. We are on the computer and it's hard to listen to the knock. 
Fleet Mechanic
Joined: Feb 2005
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From: Northern Colorado
Did the fuel filter look black when you changed it?
Is there any signs of oil in the coolant?
Does it smoke when idling or cruising?
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I just went and checked the codes again and they were po603 and po470. The knock goes along with the speed of the engine just slightly louder than normal engine noise. The only time it makes the noise is when you come to a complete stop. The fuel filter was a light brown color nothing out of the ordinary with that. Sometimes blue smoke when idleing
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Post Fiend
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From: Texas
I just went and checked the codes again and they were po603 and po470. The knock goes along with the speed of the engine just slightly louder than normal engine noise. The only time it makes the noise is when you come to a complete stop. The fuel filter was a light brown color nothing out of the ordinary with that. Sometimes blue smoke when idleing
If you pay attention, what you will hear while holding steady at 50 mph is the injectors firing. That's the diesel rattle of the engine. When you let off the accelerator and slow down, the rattle will stop. This is when your injectors quit firing. When you slow down enough, the injectors will kick back in. See if you can notice the knock come back with the injectors.
Go Bills !
Joined: Jan 2008
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From: Buffalo, NY
I changed my oil on my flat black top driveway. started it for a couple minutes to make sure the filter was full and such. Then i let it sit. A few minutes later i topped it off right on the mark giving it time to drip into the oil pan.. She was perfectly on the fill mark. Perfectionist you might say. Plus it gives me a reason to have another beer. Then i moved it over to the yard. Slight tilt and taper it sat in the yard. The next day i pulled the stick and thought "WHAT, Were did it go".. Nervous wreck, I was under it, Over it, Inside it, Looking for the leak. Pulled it back to the same spot in the driveway that i changed the oil.. She was perfect full again. Taper, Tilts can through it off. Possibly your case in some way?
Postmaster
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From: Levittown
Could be internal o-ring failure in a inj.
Get a CC test.
Bill
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I will try Dan's test tomorrow and see if I can hear the knocking when coasting from 50mph and try to get more specifics on when the knocking noise is more noticeable or louder. I will also see if the loud knocking occurs when driving as I know my wife mentioned once that she felt the truck did not sound quite right when she was driving it at about 45mph. Do you think this could possibly be a fuel injector problem?