I used seafoam a little while ago and just got back from deployent truck has not moved and still has bad rapping noise now, after using seafoam. No power loss at all runs perfect just sounds bad, any ideas before I just pull motor and drop in a replacement. No DTC at all either ! Please Help

 

Sounds like you need to change the oil.

Also, your sentence structure is a little odd. Did it have this issue *before* the Seafoam ("still") or *after* the Seafoam ("now")?

 

when i first put seafoam in my truck and start it, it makes a rapping noise too and has a rough idle for maybe 5 seconds and goes back to normal. i run a whole can 50 miles before every oil change...as said change your oil and try to start it then, monitor oil pressure. does it do it under throttle? sound like a stuck lifter?

 

what in the hell is a rapping noise? lol

how are your using the seafoam pouring it in the oil fill? vacuum line?

 

Lifters my dear friend from what you say. Get the LS7 replacements. It's a known issue and has a TSB. The sea foam prob prematured it as well, what's the mileage?