2008 Sierra 6.0 2500 cold start clatter why ?

[333Fitter]

Only on cold weather starts engine has a clatter for bout 10 or so sec then goes away.

ive been thinking it was lifters but I’m not 100% sure yet ?

does anyone know what causes this ?

Thanks in advance ,,,,,,Doug

Edited August 22, 2021 by 333Fitter

[Adamog45]

intake manifold gasket leak. Cold Start Sensor going bad. Varnished throttle body butterfly. Fuel injector fouled.  Way too many things.  Oscilloscope, 10k computer. jmho.

[CamGTP]

What's a cold start sensor? Are you sure you know what you're talking about here with LS engines?

 

A video of the issue would be more helpful.

 

Having lifter clatter isn't uncommon and same goes for piston slap. Both happen on cold engines. Even seen broken exhaust manifold bolts cause cold start noise that quickly goes away as the exhaust warms up.

[swathdiver]

On 8/22/2021 at 6:45 PM, 333Fitter said:

Only on cold weather starts engine has a clatter for bout 10 or so sec then goes away.

ive been thinking it was lifters but I’m not 100% sure yet ?

does anyone know what causes this ?

Thanks in advance ,,,,,,Doug

Mine did this with plain Mobil One oil and doesn't do anymore since I started using ACDelco's oil, same weight, both full synthetic.

[333Fitter]

You mean Dexos oil right ?

I’ll look at that next time I change oil.

thank you ,,,,

[swathdiver]

On 8/25/2021 at 8:35 PM, 333Fitter said:

You mean Dexos oil right ?

I’ll look at that next time I change oil.

thank you ,,,,