Hi guys,

Every time I go to start up my '95 Tahoe vs. my '99 Burb, I note that the '99 has a lot more 'clatter'. It is much louder at startup, and although it settles down, it never really gets quite as quiet as the '95. I realize there are a lot of differences - different ECM, different IP, different cooling system components, etc.

Can you guys explain to me why the '99 is so much louder? It seems to run just fine. We've had it for a year now, and with regular maintenance, it has always sounded the same. Just wondering....

Sincerely,

Rob :)

TDC Offset has something to do with 'Clatter'.

Compare both truck readings...

TDC off set and cold advance, when clattering loudest you should see idle rpm up as well, as she warms up rpm comes down, same as clatter

Bill check yr PMs, I sent you a note yesterday

TDC Offset has nothing to do with it, and the pumps 95-02 6.5 pumps all supercede to the same one.

98 and up ECM runs a lot more advance than earlier models, especially our old OBDIs.

I beg to differ on offset, my clatter definately increased with more offset ecpecially on cold days.

I dont know what it is but my current truck is a lot quieter cold or hot, than my 93 mech. 6.5. That Mutha would wake the dead in the morning and wasnt much better when she warmed up......she sure ran good though.

Same way with cummins 5.9's....Ive heard some that you couldnt have a conversation 20 ft. away, and then the one I have that I'm planning to put in my burb is quieter than my 97 6.5......Its gotta have something to do with timing maybe?

"..Its gotta have something to do with timing maybe?" It has a great deal to do with timing. The different engine configurations react differently but, if you advance the timing on most diesels, the noise level goes up. Try it on a 53 or 71 series Detroit!

It has everything to do with timing. The pumps internal advance is controlled by the PCM, 98+ PCMs are programmed to run more advanced than earlier ones.