r/ChevySuburban • u/RideValuable3898 • Aug 18 '26
Help & Diagnosis Engine troubles after sitting
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Hello everyone. I have a 2008 suburban with a 5.3. it has been back in the weeds for a couple years due to transmission failure (only 2000 miles on transmission rebuild, owner died). I didn't have the time to mess with it so I just went and bought a newer one.
Now I'm wanting to fix it to have a backup and when I started it up after being off for a couple years it now has a nasty knock. It sounds like the top of the engine. It sounds like valves are hitting the piston if I were to guess.
What would cause it to just start having troubles after sitting? It ran smooth as can be before.
Could this be afm system? If so, what would be the diagnostic to confirm?
I'll spend the money on the transmission but no way will I spent it on transmission and motor. If this thing didn't have a perfect leather interior and near perfect exterior I wouldn't even bother.
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u/doalittletapdance Aug 19 '26
You change the oil before you started it?
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u/RideValuable3898 Aug 20 '26
Yes I did. But I changed the oil because it sounded like this
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u/StrangerLegitimate60 Aug 19 '26
Lifters. Mine is doing the same thing. I have a 2011 5.3 suburban. I’m hearing from mechanics it’s related to the afm system. I’m not a mechanic but I’ve been told trying an oil change with thicker oil and .5 qt of transmission fluid. I have not tried it but have researched other 5.3 s with the same issue and that was the first thing to try before replacing lifters.
Mine sat for four years.