rposey

[RPosey]

I hear a sound in the engine compartment that cycles on for about 10 seconds and off for about 5 seconds. Do all of the 2003's make this sound? I typically hear it at freeway speeds but I can hear it under other conditions also. It is not the air conditioner. I wonder if it is the fuel pump? Has anyone heard this sound on there 2003 truck

 

[timjones]

NO

 

[rashwor]

I suspect...

it is the fan. These tend to make a lot of noise when they come on at highway speeds.

 

[Dean Upson]

That fan sounds like a small plane when it comes on, it will get your attention the first time you hear it :--) . The G2's problably sounded the same, but you couldn't hear them over the engine .



Dean

 

[RPosey]

engine compartment sound

I thought about the fan ,but I can't believe it would run that much on level ground at highway speed. This noise is on going anytime the truck is running at highway speed. I could understand the fan running if I was pulling a hill or loaded. I am listning if you have other suggestions.

 

[Prairie Dog]

The fan thing has been talked about before here. There doesn't seem to be any logic to when it runs. I drove the new truck for months, even down to So. Cal and back with a trailer and it never came on. Then one day it finally roared to life when I was driving through a parking lot with the A/C on. Temp gage wasn't even up to 200.

 

[Brian-NX9O]

I had the same noise within about 400 miles of new. I had the dealer check it out and they had to replace something in the heater system. It was especially noticeable when getting off the interstate. I'll see if I can find the service sheet from that repair. Unfortunately, that was back in Oregon and in January.



Since I had never had a diesel before this truck, I was almost embarrassed to ask about the noise. I am glad that I did. It was diagnosed on a one day visit and then replaced on another one day visit about a week later.



Good Luck,

Brian

 

[bighammer]

It DOES sound pretty tough when it comes on just before runnin thru the gears in town.

 

[Brian-NX9O]

Soft Cyclic Buzzing Noise

It took a bit of searching and collecting, but I needed to get my truck paperwork together finally.



The very similar noise that I had was the vacuum pump cycling on and off almost constantly. It seems the reservoir would not hold vacuum and the pump was overstressed. My dealer replaced the a "motor p/n 53032373AB" and the "Res p/n 55035614". The later description is difficult to read from the photocopy of the work order, but the diagnostic notes mention the "electric vacuum pump motor" and the "vacuum reservoir".



Apparently they had to go in through the top front of the truck to the upper part of the firewall. Their notes indicate they had to remove and replace the wiper blades, hood seal and cowl cover for access.



The primary diagnostic sounds pretty simple, "... pump motor cycling all the time; plugged vacuum lines; pump still runs. Tested res, won't hold vacuum. " The truck had 531 miles on it at the time.



I hope this is helpful.



Good Luck,

Brian

 

[MMeier]

PDog, and anyone else listening, I believe the fan is tied into the A/C system and is designed to kick in any time the high pressure side hits a certain PSI. Sounds *****in cruisin thru a parking lot with the fan going and my missing silencer ring though!

 

[SRadke]

Brian,

I'm not sure about those service techs. I don't think the 03's use a vacuum pump. Can anybody help me out here?



I too had a noise when I got my truck that sounds just like what was described. Definitely not the fan. It has either gone away now at 7K or I've begun to ignore it, not sure which.

 

[Dean Upson]

I believe the '03's have a small electric vacuum pump for the heat and a/c controls.



Dean

 

[SRadke]

Thanks Dean, that is good to know. I guess I assumed they had converted the whole rig to electrical switches when I found out they removed the mechanical vac pump.

 

[Brian-NX9O]

I hear "It's a Small World After All" in my head....

SRadke,



I bought the truck in Corvallis at Wilson Motors. Kaye at the service desk wrote the work orders for the above repair.



They might even remember me. I had the truck in Corvallis for about 5 months before taking it to Georgia. The work order had a Corvallis address with a Georgia 404 area code contact number! (cell phone)