2008 sierra duramax . ive had an odd noise since i bought the truck. finally decided to snoop around. took serp belt off to rule out noise in the drive accessories. still there. started listening to screwdrivers. put it on the outlet line at my cp3 and i could hear my noise. it sounds like alarm clock bell or typewriter type deal. truck runs fine no smoke unless floored for just a second. it is egr deleted. why would it be making such a noise? its not crazy loud and noticable just annoying. i think it does have a light performance tune. nothing crazy
LMM cp3 making noise?
- Thread starter dominator200
- Start date
GM has a service letter our about the Duramax "typewriter" tick. Very common especially after an oil change. From what I have been told this is an air pocket that can develop in the lifter passage. Some are worse than others. My 08 used to do it and take about 50 to 100 miles for it to clear up after an oil change. Now that I have 190K on it I don't hear it anymore. Dean
thanks for reply. im pretty sure its not a lifter nouse. oil was changed a while before i got truck. ive put 500 miles on it noise has never changed. with a screwdriver against outlet of cp3 i can hear tte noise perfectly. damn near feel it against my ear with screwdriver lol
Maybe someone with more CP3 experience than I can answer but if the CP3 was going out there would be many symptoms of that and you are not experiencing any of them. The only thing I can think of if is you are sucking a bit of air in thru the factory filter head. Not enough to give any codes but a small bit of air will produce sound out of the CP3. Are you running a lift pump? I work with aircraft hydraulic systems that operate at 3000 psi and cavitation or air ingestion even at that pressure will make quite a bit of sound. If it is air you will need to either rebuild your filter head or add a lift pump soon. The CP3 won't last long without sufficient fuel to help lubricate the pump. Dean
Do you ever loose prime or take a while when starting after sitting? A decent lift pump is a great investment in a pre L5P Duramax. I don't go for all the increased mileage some boast about but a definite in idle quality and a long CP3 and injector life even for a stock LMM. Dean