Loud Knocking
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Loud Knocking
I have an 1994 E350 box van. My 7.3 idi is tapping very loud. It runs great. No smoke, easy to stat, runs cool, good power, great oil pressure. The diesel shop I bought it from said it has always done that. He says it's an Injector. The truck has just over 200,000 miles on it. The noise sounds like somone is hitting the oil pan with a wrench. It knocks hot or cold. Sometimes the knock goes away when I am driving. It always knocks at idle. Everyone keeps telling me my motor is about to blow. If this were a gas motor, I would say a bad valve. But it runs great. Help!
Elder User
Joined: Feb 2007
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From: Mississippi
conventional wisdom says bad injector. you can crack fuel lines open one at a time adn see if it changes running. do one at a time and you can locate which injector it is. plc7 (I think) says something about weak injector not putting fuel in properly and causing piston to do something something (memory not what it used to be) and make the knock. that said, it's probably not going to go "boom".
speedrdr
speedrdr
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Joined: Nov 2004
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From: Manitoba
A bad injector will fire early and cause a noise like a lower end bearing knock especially at idle. With 200K have the injectors ever been replaced..... are they and the return lines/plastic caps .....grey painted.
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I know the shop I bought the truck from said they replaced the injectors. I am not sure if they replaced all of them. I know the knock comes from the pass side. It seems like the lower end, but the pitch is off to be a bearing knock. I need to know what this noise is, because this is my work truck. If it goes down, I can't work until I fix it.
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The truck is a 1 ton. I have an automatic trans that was replaced within the last 30k miles. The sound is coming from what sounds like the bottom of the motor. I don't think it's a rod, because I have had the truck well above 70 mph and it still runs great. The knock is very loud, but sometimes it goes away briefly when I am coasting down hill.
Lead Driver
Joined: Jul 2007
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From: Rhode Island
I'm no expert, but from what I've read in this thread, if it goes away when your coasting down hill, when your fuel pump would be sending very little fuel till the injectors, then your injector is probably your problem if it can cause loud knocks like PLC7 said
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I have worked on plenty of gas motors, but not diesels. If I crack open the injector lines one at a time, what will this show me? What am I looking for? If the injectors have been changed recently, is it worth the effort to check them? I have read so many similar post about the same problem where changing the injectors and lines has done nothing for the prob.
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Lead Driver
Joined: Jul 2007
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From: Rhode Island
Originally Posted by Mrdmcw
I have worked on plenty of gas motors, but not diesels. If I crack open the injector lines one at a time, what will this show me? What am I looking for? If the injectors have been changed recently, is it worth the effort to check them? I have read so many similar post about the same problem where changing the injectors and lines has done nothing for the prob.
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I just did the ol'screw driver to-the-ear test and the noise seems to be coming from the bell housing area. I know the trans was changed at some point. From what I have read I guess it is the converter or fly wheel. What checks should I perform? What should I look for? 1 ton auto trans on a 7.3 non turbo IDI.
Post Fiend
Joined: Nov 2004
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From: Manitoba
Pull the flywheel lower cover off and look around inside....... your looking for cracked flex plate or loose nuts on the Tconvertor bolts...... possibly a loose flexplate on the crank also...... just look for something out of the ordinary.
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From: mooringsport louisiana
Have you cracked each injector line one at a time with it running ? As you loosen each one you should notice it will start to miss . Tighten that one up and move to the next . If you find one that doesn't make a difference , then you have found the cylinder with the problem .
I had a 7.3 that sounded like it was coming apart , loudest knock I ever heard from an engine . It turned out to be a blown head gasket .
I had a 7.3 that sounded like it was coming apart , loudest knock I ever heard from an engine . It turned out to be a blown head gasket .
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When I put my ear on each injector, I did not hear the knock. Also the motor runs very smooth. Starts up easy every time and only smokes a little on heavy throtle. Do these motors run good even with internal damage? My thought on the noise coming from the bell housing is that the knock is transfered down the crank to the trans. What do yall think?