I have 191k miles on my 2005 F-150 with 5.4l V8. It was clattering and missing badly so my wife had it towed to the dealer. I was expecting to have to replace the VCT solenoids, but the service advisor says the main bearing is worn, allowing fore-and-aft play in the crankshaft and oil leakage, so I really need a new engine - replacing the VCTs won't be enough to get it running. A new engine he says is $7700, and even a rebuilt one will cost $5000 with labor and parts. I'm doubting that it's worth even the cost of the rebuilt engine. Who knows what the next major repair will be -- catalytic converters, transmissionm, a/c, shocks, etc.

Is the engine replacement really necessary or is he exaggerating?

 

I can tell you the cost of the repair isn't worth it for a 10th gen truck without sentimental value. If the main bearing is shot (not very common on these engines as far as I know) then the oil pan, main caps, and likely the rods have to come off. Then new thrust bearings installed and everything put back together. But, and here is where I'm not sure of the process, you may need the engine out and at rest to get a valid measurement for bearing clearance. At which point then engine is out and putting in a remand engine is a lot less likely to fail a thousand miles later.

You may try to have another dealer/shop check it out. Sometimes things are misdiagnosed (purposefully or accidentally).

 

You're motor is smoked. Time for a remanufactured motor. It'll be cheaper than buying a new truck!

Fraser and Powertrain. Look to those companies for the best price/warranty. They are the same exact motors that you'd get from Jasper and even Ford. All updates done. 5 year/100,000 mile warranty.