5.3 with dreaded AFM noise but at 2200rpm?

bobejones · May 17, 2016

Have a 2008 Tahoe for about a year now. Just did an oil change to Quaker State Dexol oil and TG series filter. This was the first oil change "I" personally did on this machine. I noted the filter for this engine was a slightly different number from my older 5.3s and figured it had an extra bypass valve or something?

The engine does not use oil and does not have any cold or hot start noises but picks up a very audible valve tick at 2200-2300, and is not present at any other rpms.

I knew there were some risks getting one of these "fantastic" AFM engines. I am curious if the noises will lead to more trouble or if the noises can be ignored? It seems GM is pretty moot and indicating noises are "normal" so lets just run er! If that is truly the case, I am happy to ignore it until we can get around to selling it but I am sort of wondering now if this is an oil or filter thing. ?

newdude · May 17, 2016

Try changing that filter. Get an AC Delco one, either the PF48E or the UPF48R. Does the tick occur in V4 or V8 at 2200-2300rpm?

bobejones · May 17, 2016

That is a good question! I will find out. Seems to be purely rpm dependent, not load so if AFM will kick in in 3rd, I can test that. I didn't even know there was a noise until I drove it other day. Of course the other half was like "what noise?"lol

I am reading more into what is causing these issues. I am an engine builder and mech engineer so I tend to want to know EXACTLY what is going on. This sounds like lifters losing prime but oil pressure seems reasonable. IIRC, the OPS is at the top back of the block so that should be what the valve train is seeing BUT I was just reading where there is an Oring on the pump pickup tube that goes bad causing air intrusion! Um, that would sort of make sense with the chase on the Dexos oil deal dealing a lot with oil foaming.

I hope I have a simple problem here.