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Old 07-10-2020, 09:02 AM   #1
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Engine noise on start up

This start up video is after sitting for over 2 weeks. One little puff off black smoke on initial start which isnít a problem. My question is about the change in tone at the 15 second mark. Itís much more noticeable in person. I donít know how to describe it. Itís not a change in RPM, or a change in pitch, Moore like a change in the harshness of the diesel sound. I havenít noticed that it ever goes back to the initial tone until the next start up. Also havenít shut it off and restarted it immediately to know if it only does it on cold start up. Any ideas?

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Old 07-10-2020, 09:21 AM   #2
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Is that the sound of the EGR valve being open? It does have a more 'hollow' sound after 0:15, doesn't it?
Just my guess...
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Old 07-13-2020, 09:39 AM   #3
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I don't know enough about these to know if it even has an EGR system. I looked the engine over and didn't see anything that resembles an EGR valve that I'm familiar with.

Anybody else have any ideas?
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Old 07-13-2020, 10:08 AM   #4
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No egr on a 99.
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Old 07-13-2020, 10:15 AM   #5
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Sounds like a load of some sort is being applied to the engine. Like the alternator being turned on or some other load. You can remove the valve cover and do a valve lash inspection/adjustment.
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Old 07-13-2020, 11:28 AM   #6
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I don't have any ideas, but I wanted to chime in with a "me too."
Mine is also a '99, and it does this noise change on every cold start. I haven't noticed whether it does it on warm starts, but I will look for it now.
It doesn't seem to have any effect on how well my engine runs.
I had also been guessing that it was some accessory kicking in, like maybe the air pump.
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