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88 ford 7.3 idi knock?

 
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Old 02-09-2019, 06:40 PM
mucksmobilewelding
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88 ford 7.3 idi knock?

i have a 88 ford super duty 7.3 idi / loud knocking noise. Today on the highway acted as if it was missing very bad and was smoking white with slight blue tint. I replaced 4 injectors and no change. Does anyone know whats going on ?
 
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Old 02-09-2019, 08:01 PM
DarkOverCast
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You could try cracking an injector line one at a time to see if the knock disappears or gets quieter.

If it disappears then change that injector.

If it just quiets down and a new injector doesn't fix it then that rod bearing on that cylinder is probably bad
 
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Old 02-09-2019, 08:34 PM
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how much is a rebuilt kit
 
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Old 02-10-2019, 12:34 AM
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Originally Posted by mucksmobilewelding View Post
how much is a rebuilt kit
Ok, I am going to try to lend a hand here. First, before you go the rebuild kit and pull the motor route, lets try to diagnose the problem. I'm going to write out the steps I would take, and other might jump in, if my steps are not effective or not complete.

First, lets rule out all the other things on the truck. Be sure the engine noise is what you hear. Start the truck, and roll down the window, listed to ensure that the noise appears at idle and at say 2,000 rpm. Next would be to drive the vehicle, and ensure that you are not hearing transfer case noise, or any u-joints. This should be rather obvious but I am wanting to simply focus on the problem by eliminating everything else.

Next, would be to test the "back yard way" for a dead cylinder. With the key off, jump the solenoid to force the starter to engage. Let it cycle it for a few seconds and listen for any signs of an obvious dead spot. This would let you know a rebuild will be required, or in the best case that the engine is mechanically fine.

If the above did not narrow down your problem, and the engine functions correctly without fuel, than we can go to the fuel injector being the problem, or possible valve train. Lets first test injectors, you will need a Mechanic's stethoscope, which can be bought just about anywhere for like $10. This will allow you to narrow down noise to a certain area, and a certain bank of the engine. From there, with the engine running for a period long enough to warm up, you can shut off the engine and feel the suspected injectors to see if one is much hotter than the others. That would be your bad injector. If an injector was not the problem and valve train is lets say "rattling" than you would need a new camshaft as these engines are rollers. So when the valve train starts to make noise, they usually are toast. The mechanic's stethoscope should help you determine all of that.

best of luck. Report back if things can not be narrowed down with the above.
 
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Old 02-10-2019, 09:32 AM
mucksmobilewelding
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i cranked the motor with the key off and i can here a clicking noise but also found some air intrusions and my fuel line connector to injector was cracked. fixing now will update later
 
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Old 02-10-2019, 05:40 PM
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can none working glow plugs cause missing and knock? 3 are broken
 
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Old 02-10-2019, 05:42 PM
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Originally Posted by mucksmobilewelding View Post
can none working glow plugs cause missing and knock? 3 are broken
Not unless they are broken in the physical sense. Typically they could cause some issue, but only when cold, or if they had broken off entirely and left an exposed hole and lots of damage.
 
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Old 02-10-2019, 06:12 PM
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3 wires are not connected to the plugs. plus checked valves and seen nothing wrong .5 injectors had to have the bottom of them pulled out of the head only the tops unscrewed
 
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Old 02-10-2019, 06:35 PM
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Originally Posted by mucksmobilewelding View Post
3 wires are not connected to the plugs. plus checked valves and seen nothing wrong .5 injectors had to have the bottom of them pulled out of the head only the tops unscrewed
You were able to get them out however? None of them broke off inside and left bits inside?
 
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Old 02-10-2019, 07:13 PM
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no they where pulled out
 
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Old 02-10-2019, 07:15 PM
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Originally Posted by mucksmobilewelding View Post
no they where pulled out
Then that would only be your problem if the missing was very short when it was cold then cleared up. Otherwise that would not cause your symptoms.
 
 


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