Any ideas on the noise

[Tinbender]

Last weekend when towing in the mountains I noticed a engine noise as the transmission shifted into OD. In Tow/Haul mode and cruise set at about 60, as the transmission got ready to shift it appeared the engine would momentarily flatten out and a noise or clatter, ( the best I can discribe as simular to preignition knock on a gas engine) for about 1-2 seconds and then the trans would shift and everything goes back to normal.

Took it in the dealer and they said they never heard of that complaint and want me to hookup the trailer so they can see it for them selves. We're going to make a run on Tuesday morning. I'm at a scale weight of 18,000 CGVW.

Has anyone else experienced anything like this? Maybe a few ideas would help.

Thanks, Bob

[mdrag]

Tinbender,

If this noise occurs around 2500-2600 RPM, it is likely the pilot injection turning off - and this is normal. When the pilot injection turns off, the Dmax sounds more like a typical diesel.

[markf]

Tinbender,

It is the Pilot Injection turning off. I had the exact thing happen when pulling Mt. Hood with my 32' 6 horse trailer. Noise hit around 45mph right at the shift. It also happens empty when I jump on it going up hill. Everyone says it is normal, but I would like to know myself why this happens. It sure was fun running Mt. Hood at 50mph however.

2002 3500 CC D/A 4x4
SLT 40/20/40 leather
pewter/neutral
32' Silverado 6 horse

Other diesel
98 D@&*$e 3500 24-valve cumm*@#, 5-spd
(It's the wifes)

[mark45678]

all sounds normal.... in t/h it will defuel a little longer due to having the converter un lock and up shifting! its not as noticeible in drive mostly because its shifting quicker and has slightly more load on it(more fuel). the part about not up shifting at 60 is normal in t/h it will up shift under light load around 64ish