Engine/Transmission (1998.5 - 2002) Explain this one to me

[Sageair]

I have noticed that my 2001 ETH is quite a bit noisier (clatter) when cold but quiets down after about 15 miles of highway driving but today I left out of Boise Idaho headed for home in Northern Nevada. It was cold (27 deg F) and foggy for the first 80 miles. I was thinking man this thing is loud and it should have quieted down by now. Than I broke out into the sun ,outside air temp jumped up to 43 deg and all was well again. What took place? Second question although my mileage with 3:54 and pretty conservative driving (70 mph) is'nt bad about 17 mpg I think it should be a little better. If the timing on the pump is off wouldthat have much effect on my mileage. ?Power is good and truck just seems to generally run very well but I'd sure like to get my mileage up some. Thanks in advance.



P. s I know about the winter fuel thing but my mileage has been about as noted above all summer as well Steve

 

[Rob Thomas]

When I switched to synthetic oil, all my "cold" engine noise went away, instantly. Can't help you on the mileage, sorry.





Later, Rob

 

[tgbol]

Your mileage seem to be about the same as mine. If I am running at 70. drop back to 55 and I get about 20.

As far as the louder engine in the cold and foggy I have noticed that too, but chalked it up to being more aware of my surroundings

 

[klenger]

How many miles on the truck? They really need 10,000 - 30,000 to break in well.

 

[A Johnson]

The I S engines will change timing based on intake air temperature. The colder the air the more timing advance is given therefore a noisier combustion cycle. I know this is true with the ISC and assume it follows to the ISB series. Also it would make sense that the colder the intake air the less growth of the intake valve stem and wider the rocker lever clearances than when warmer air is present and more stem growth.



A Johnson

 

[Adam]

It's the weather

I think it's just the reflected noise. I notice when I'm outdoors in heavy fog or snow, every little noise is reflected. I can tell when a front is moving in while I'm at the shooting range just by listening to the echo of the shot. It would stand to reason if the air is denser, more noise is retained or reflected back than would normally be the case in clear conditions. Just my understanding of (very) basic atmospheric conditions and forecasting. I find it works about as often as the ache in my ankle and about twice as often as the ache in my knee .



-Adam

 

[RedRam1]

Sageair,



It looks like our trucks are just about identical... and so is our mileage. I have kept track of every gallon I have run through mine in 25K miles, and 17mpg is what I average in a combination of city/highway driving.

I installed a Power Edge EZ at around 7K miles, but did not see the mileage increase others have reported. My best mileage was 21. 5 mpg; this was straight down the highway, empty, at around 65 mph. On my 21. 5mpg tank, I was driving as conservatively as possible, trying to maximize fuel mileage.