Car :
1999 Cavalier z24
Mileage:
176,000 miles
Engine:
2.4 ld9 twin cam
Transmission :
4t40e 4 speed automatic
Issue :
Short sharp rattle noise during cold startup
Experiencing a short sharp rattle noise during cold startup lasting for about the first 2 seconds very briefly after startup then it stops. Engine runs quiet and smooth while idling and while driving. It only makes the noise at first cold start up in the morning or after it's been sitting for more than a few hours. I know there's a TSB for the ecotec engines concerning this same issue and it says that it could be because the "cam phasers" are not "parking" properly.
Does the ld9 have "cam phasers" and if so, could this be what's causing the noise at start up ?
The LD9 doesn't have any cam phasers. Some higher mileage LD9s can have the oil check valve stick open. It is a ball that keeps oil in the head for starting. The bad part is it is in the block, and you have to remove the head to inspect it.
Normally it is a tapping noise and not a rattle. I have had a starter go bad and still function, but it was more of a grinding noise.
Rattles are normally heat shields.
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
Timing chain tensioners and guides can rattle when cold. Ive sold a couple of sets of guides for LD9s. They like to shatter as the age of the engine goes up.
It has about 200 miles on a brand new timing chain kit from PCI preffered components which includes chain, chain guides, tensioner, cam sprockets and a new GMB water pump. It almost sounds like the timing chain rattling briefly at start up, especially cold startup. I'm almost 100% sure that everything was installed correctly as it was installed by my friend who is an ASE certified mechanic. I do not recall it doing this before I had these parts replaced. Could it be the PCI tensioner not performing properly ?
I've heard of people using the older style spring loaded tensioner instead of the 97+ tensioner which is spring loaded and hydraulic, operating off oil pressure, however I have read that the mechaincal tensioner is for 96 models only and not to use it if your car came with the hydraulic tensioner. Should I convert to the old style mechanical tensioner ? If converting from hydraulic to mechanical tensioner, won't oil pour out of the block where the hydraulic tensioner goes or do you leave the mechancical tensioner in place ?
Do this.
Pull fuse/relay for your fuel pump. Then turn the key (crank the car) about 3-5 seconds, do this 3 times. Then put the relay back in and start the car. Is the noise gone? Maybe do this a few days to verify.
FU Tuning
I'll try it and post back with the results.
I tried pulling the fuel pump relay, cranking the engine over for a few seconds and then putting the fuel pump relay back n and it started up real smooth and quiet.
