Screw in cylinder disaster

6TEEN5.3 · July 9, 2021

Hello everyone! Does anyone have an idea how a screw from the MAF sensor could have ended up in cylinder #1? I towed my truck to the dealer after it started knocking badly. Techs found a screw inside the engine and found that the MAF sensor is missing one. Needless to say, the 5.3 is done and at 70k miles I’m out of GM warranty. Extended warranty refuses to replace the engine since it was a “foreign object” that caused the issue. Dealer quoted me at roughly $12k between parts and labor for the replacement. Has anyone experienced or heard of anything similar? I’m currently seeking legal help to take further action with the extended warranty company.

silveradosid · July 9, 2021

do you have the stock intake system on your truck, a screw that size would have got trapped in one of the corrugations of the stock system. next would be find an independent shop. the knock is probably a jammed lifter from the screw hitting the valves. if the cylinder isnt scarred and the cam is ok, piston and rings, lifters and pushrods and a new head and put it back together

6TEEN5.3 · July 10, 2021

18 hours ago, silveradosid said:

do you have the stock intake system on your truck, a screw that size would have got trapped in one of the corrugations of the stock system. next would be find an independent shop. the knock is probably a jammed lifter from the screw hitting the valves. if the cylinder isnt scarred and the cam is ok, piston and rings, lifters and pushrods and a new head and put it back together

Yes it has the stock air intake. I should mention the truck was rear ended pretty hard which I think had something to do with it. It wasn’t hard enough to bend the frame but it did break the driver seat bracket. I sent pictures and a video of the knocking to a couple different shops and both said it needs a replacement.