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loud knock

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Old Oct 1, 2009 | 11:40 AM
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loud knock

When the engine is cold and i first start it the motor knocks louder than normal, But after about 2 minutes it goes away. Then the motor sounds like it should. Could this be the oil pump finally pumping the oil after about 2 min? If I hold the petal at about 1000 rpm's when first started its not loud but still louder than normal.
 
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Old Oct 1, 2009 | 04:08 PM
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Sounds like a leaky Injector.
 
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Old Oct 1, 2009 | 05:25 PM
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or just your fast idle until your motor is warm enough.. it will jump up about 500 rpm extra until its warm which is usually 2 minutes for me
 
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Old Oct 1, 2009 | 07:44 PM
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Originally Posted by 84 f250 6.9
or just your fast idle until your motor is warm enough.. it will jump up about 500 rpm extra until its warm which is usually 2 minutes for me
I dont think my fast idle is working correctly. When cold it starts at about 600-700 rpms. I hold the pedal at 1000 rpms. to let it warm up for about 2-4 minutes. (I need to look at it i know) Now after it has warmed up after road driving it idles around 700-800 rpms or so. I was just concerned about the engine/oil pump. Everyone that hears it when i first start it have the same reaction. "Man that's loud".

"IDIDieselJohn Sounds like a leaky Injector."

It has new, injectors, lift pump, injection pump, and glow plugs. Under 1000 miles on all of it. Plus it did this before all the work was done to it.
 
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Old Oct 1, 2009 | 08:29 PM
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The timing could be too advanced and the timing advance places it even further advanced.

Fast Idle Adjustment

At Cold Idle Solenoid:

1. Place transmission in NEUTRAL or PARK.

2. Start engine and bring up to normal operating temperature.

3. Disconnect fast idle solenoid from wiring harness.

4. Apply battery voltage to solenoid to activate it.

5. Rev engine momentarily to set solenoid to activate it.

6. Check fast idle speed setting. Fast idle rpm should be 825 ± 25. Adjust to specification by turning solenoid plunger in or out (Figure 11).

7. Rev engine momentarily and check fast idle rpm. Adjust as necessary.

8. Remove battery voltage from solenoid connector and connect to wiring harness.
 
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Old Oct 1, 2009 | 09:36 PM
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Would you say it sounds like a 7.3 Power Stroke engine when you first start it?
 
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Old Oct 2, 2009 | 12:04 PM
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Originally Posted by Dave Sponaugle
Would you say it sounds like a 7.3 Power Stroke engine when you first start it?
Cant say for sure, being i have not paid attention to a power stroke start. But I would have to say mine would be much louder.
 
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Old Oct 2, 2009 | 04:23 PM
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I don't mean when they start, the 7.3 has a rattle, Power Stroke rattle, when they are idling hot or cold.

Advanced timing on an IDI will cause the same rattle while the timing advance is on until the engine temp reaches 112 degrees and it returns the timing to normal.

If the timing was set incorrectly by someone in the past, the Power Stroke rattle could be present at all times, just much worse when the timing advance is on.

What is causing the rattle is combustion starting before the piston reaches TDC, so it would be like spark knock or detonation on a gasser.
 
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Old Oct 2, 2009 | 08:32 PM
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Originally Posted by Dave Sponaugle
I don't mean when they start, the 7.3 has a rattle, Power Stroke rattle, when they are idling hot or cold.

Advanced timing on an IDI will cause the same rattle while the timing advance is on until the engine temp reaches 112 degrees and it returns the timing to normal.

If the timing was set incorrectly by someone in the past, the Power Stroke rattle could be present at all times, just much worse when the timing advance is on.

What is causing the rattle is combustion starting before the piston reaches TDC, so it would be like spark knock or detonation on a gasser.
Sorry, miss read it. OK yeah I would say it would kinda sound like that. But much louder. This would make complete sense being it goes away after warming up. I need to check the timing in the morning.
 
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