What's knocking
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Joined: Jun 2007
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From: the great northwest
What's knocking
I have a 1994 F-350 4x4 crew cab w/ a 460, 160k miles, lifted 4", 35" BFG's, New Transmission w/ billet torque converter, does not use oil or water, decent mileage, no issues when I tow grossed out at 23k. last week I noticed a knocking noise in the lower end, it speeds up abit when you rev the motor, now it's getting louder. What I've done: drained out 1 qt oil and repalced w/ 1qt synthetic oil., thought maybe I had a wrist pin dry, it quieted down for a couple of days, then started again. changed the oil after 1500 miles and it still does it. I had my drag racer neighbor listen to it, he's never heard anything like it, it sounds dull, but still loud...any idea's, or should I yank the motor and freshen the whole thing up?..I need to figure this thing out, vacation is coming in a few weeks
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Joined: Jun 2003
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From: Rose City, MI
what color was the oil you drained out?? was it clean, light, dark, kinda graphite colored? hows the oil pressure?? Do you use any oil additives?? Is the noise louder under a load or when you rev it unloaded? These questions may help find problem.
Good Luck, Ben
P.S. I had 2 rod bearings and the center three mains go out in my other brand big block after i did the top end. When i drained the oil out it looked like liquid graphite. Wasn't makeing loud noises but did chirp a bit at idle. BTW if you oil pressure gauge drops at idle when warm you have some worn bearings.
Good Luck, Ben
P.S. I had 2 rod bearings and the center three mains go out in my other brand big block after i did the top end. When i drained the oil out it looked like liquid graphite. Wasn't makeing loud noises but did chirp a bit at idle. BTW if you oil pressure gauge drops at idle when warm you have some worn bearings.
Last edited by 85F_150driver; Jun 26, 2007 at 10:53 PM.
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sound EXACTLY like a crank bearing to me. that's what my lil brother's monte carlo did. sold it to a buddy cheap, who tore it down and said one of the crank bearings was screwed.
although, in my brother's case, the bearing issue was caused by oil starvation. apparently, the kid didn't know what the giant light that said 'OIL' meant he should do. d'oh!
Mike
although, in my brother's case, the bearing issue was caused by oil starvation. apparently, the kid didn't know what the giant light that said 'OIL' meant he should do. d'oh!
Mike
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Joined: Sep 2006
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From: Island Southeast Alaska
I'd drop the pan and brg caps. Find the bad one and if the crank ain't scored or out of round yet I would roll in a set of Brg's. Don't get the caps mixed up.
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From: Mulege south Baja ca. Mx.
good oil that delo 400 15/40 that is what I use also. if you cant find it or it doesn't clear up with the ATF then I would pull the engine and check it out. it is easier on most trucks than trying to pull the pan while in the truck and you can do a much better job of checking and repairing any damage.
good luck and keep us posted
good luck and keep us posted
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Senior User
Joined: Jun 2003
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From: Rose City, MI
mine sounded like a lifter out of adjustment, the oil drain confirmed it wasn't. To me thats a good place to start. of course mine was ok untill i put a set of 396 heads on and bumped the compression about a point. but good luck with yours.
Another chunk of change wasted on that dang thing but means more power now.
cost me 550 to get block vatted, align honed, new freze plugs, cam bearings, rods resized and new rod bolts. crank had to be replaced since it was chewed bad. machine shop said if it has to go more then .010 under then you might as well get new crank for almost same money.
Another chunk of change wasted on that dang thing but means more power now.
cost me 550 to get block vatted, align honed, new freze plugs, cam bearings, rods resized and new rod bolts. crank had to be replaced since it was chewed bad. machine shop said if it has to go more then .010 under then you might as well get new crank for almost same money.
Last edited by 85F_150driver; Jun 28, 2007 at 01:14 AM.
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From: the great northwest
Thank you all for your input. I spent the morning cleaning the shop and I will be pulling the motor. Rods, mains, etc. Better to be safe than sorry along side the freeway towing...THANK YOU again for the input...
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Joined: Dec 2006
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From: Kewanee
Mine did the same thing and i havent had time to fix it. I run rotella 15/40 and i replaced two quarts of that with two quarts of lucas oil stabilizer and the knock went away. You can run lucas up to 80%. Anyway i havent had a bit of trouble in 10,000 miles. Ya might wanna try that temporarily.
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From: Farmersville, TEXAS!
My '91 F250 (460) is making the same noise, couldn't have described it any better myself. I got under the truck while idling and the "knocking" noise I am experiencing seems to be originating from the the dual-pulley that both drive belts share. This dual-pulley is of course attached to a shaft that appears to run into the lower end of my 460... can someone please tell me what this "shaft" is, is it the crankshaft?? I recently replaced both belts and feared that I tightened one too much to cause this, but could just be coincidence. The noise started about a week after replacing the belts. Thanks in advance for any advice that anyone can offer, I really appreciate this forum and all the help folks are willing to give.
