So my truck was parked for several months while I was out of the area. After 2 days of driving in 20* weather, I realized my engine was way quieter than it used to be (99 24v 5 speed, basically stock). Previously I would have to set the stereo to #14 volume at idle, now I can hear it clearly at #10 during driving and this thing is straight piped.

Any thoughts as to what would cause that change?

It smokes black/grey during first start up in the cold as it always has. No damage to thte exhaust as far as I can tell, no serious loss of power ( I attributed the bit of extra lag to cold weather diesel fuel), and no oil burn off.

 

are you running any type of fuel additives? what is the oil pressure?.. could the truck be covered in snow that would make it seem more quiet?

 

Check under the hood for rodent nests!!

Ha ha, often times things aren't quite as we remember them, grasshopper.....

 

I am using a Cetane boost/antigel, 70+ oil pressure, no snow, no nests

 

Noise from our rigs is usually the IP. I do know when I run 2-stroke oil in mine it is noticeably quieter than my usual dose of Power Service White Bottle.

Maybe you got a good tank of fuel, I have noticed that after a prolonged highway run on my truck it shuts off a lot quieter than shorter lower speed trips....

Don't know.

 

Cetane boost will quiet it down and the fuel may be aged a bit. What were you driving while gone? Or not driving! Maybe your hearing improved while you were in a quieter environment. I say that seriously.

Rick

 

I notice with my truck...It will run smoother and quieter at -20C,than at +20C...It's got to be the colder charge of air...

Thinking that could be the same with your truck...