I have a 2004 1/2 GMC 2500 HD. I have been witnessing an injector (pretty sure thats what it is) noise above 2500-2600 RPM when at operating temp. The truck is fairly stock except fer pcv reroute and lbz mouthpeice. Right when i bought it (about 3 months ago, 88000 miles) i noticed nothing took a trip to mn (put on about 1200 miles mixed driving 55mhp to a run with a 6.0 ford down the highway at the speed governer fer a few miles) and never noticed anything. about a month after having the truck i took a trip to see the gf at school about 150 miles away and when i hit the interstate (70 miles into the trip) was passing a semi (runnin about 85ish with 245's then) and i noticed a louder than normal ticking comming from the firewall that seemed timed with the injectors. it would come and go then. awhile down the road i installed a predator programmer and when i would go through the gears from a stop i could hear the noise come in (about 25-2600 rpm) before each shift. Now i have about 98000 miles on the truck and i can make the noise just going down the road and manually holding a gear to get it into that 25-2600 rpm + range (only at operating temp when cold doesnt seem to be as loud) and it stands out i could take a sound clip sometime if yall want. I had my boss ride with me one day (Service department manager who is very nowledgeable) and he agrees its not normal and thinks its an injector problem. He said in a few months we could probably throw a set of injectors in it to fix it (2 year unlimited mileage service contract) but i am just curious if anyone had the same problem and had a solid fix. Truck runs good everwhere else and even when its noisy. No excessive smoke none at idle a little puff (very translucent) when i step it down (stock programming havent had the predator for awhile) i have noticed when taking off from work on a cold engine just a couple times (shortly after returning the truck from stock when i sent the programmer back) it smoked quite a bit but after it warmed up never noticed anything. I have done alot of research online and found posts on other forums about "GM Techs" who say the duramaxes get rid of the pilot injection at the same rpm that all do it but i agree with the origninal posters that have ridden in other duramaxes that are not as loud.
I also had a good friend (owns a small general/performance diesel shop in town) and he agrees that this is not a normal injector noise but suggested to me to check things like valve clearances and fuel pressure and balance rates. Have not done them yet as book time on checking valves is somewhere around 8+ hours. My friend also can bench test flow of injectors but this would seem kind of worthless to me as the truck runs good and no codes. So, so far my only complaint is excessive noise.
I am looking forward to your ideas as to what it could be and suggestions or things to check. Thanks for your input in advanced and sorry again for such a long post.
I also had a good friend (owns a small general/performance diesel shop in town) and he agrees that this is not a normal injector noise but suggested to me to check things like valve clearances and fuel pressure and balance rates. Have not done them yet as book time on checking valves is somewhere around 8+ hours. My friend also can bench test flow of injectors but this would seem kind of worthless to me as the truck runs good and no codes. So, so far my only complaint is excessive noise.
I am looking forward to your ideas as to what it could be and suggestions or things to check. Thanks for your input in advanced and sorry again for such a long post.
since i last posted it has started to develop the rough running idle (i think its fuel pressure sensor? please correct me if im wrong i have a buddy with an identical truck same rough running and he had a buddy help him replace something i gather on the cp3 pump (dunno if it was the regulator i dunno but i assume it has the pressure sensor on the rail like the cummins do? all we got fer anything but chrysler is a modis at work and i can see balance rates but not return rates from what i gather return is the identifier for injectors..i can command rail pressure though. just idling it will bring it up to full pressure. what causes the rough running idle again? anyways im runnin outa ideas with the injector noise. a ford diesel guy at work suggested valves outa ajustment but dont these have hydraulic lifters to take up the slack? and im not really excited about diggin into the valve covers again as book time is 10 hours to check em.. any info is apriciated thanks!
