Rebuild or Replace

[DStang99]

Hello Stangnet,

I Have a 1999 mustang gt with 160k Miles that has a loud knock at high RPM .
Should i just buy a used motor or just rebuild it if rebuild is best what all should i replace? What can i replace to gain more Power?

 

[darkside03gt]

What are your current mods? Do you plan on adding a power adder some time in the future?

 

[bhuff30]

Define high rpm. When does the knock specifically occur? Off hand, I can't think of any knocks that are only present at high rpms, so it is possible you don't have to replace the entire engine.

 

[DStang99]

What are your current mods? Do you plan on adding a power adder some time in the future?

No mods really just intake and flowmaster exhaust.
probably just add cams one day wont be adding anything like a supercharger ,NoS ETC

 

[DStang99]

Define high rpm. When does the knock specifically occur? Off hand, I can't think of any knocks that are only present at high rpms, so it is possible you don't have to replace the entire engine.

The motor only knocks when i get on it or when i rev it in park it starts to knock.
not sure what rpm it starts. I have been told i blew a rod bearing

 

[darkside03gt]

I would just replace it with a quality remanufactured engine and be done with it.

 

[bhuff30]

A rod bearing will typically be loudest at light loads and moderate rpms. For example, reving in neutral or in light driving to 2000-2500 should produce about the loudest knock. I think of high rpms as being 4krpm, so if your knock doesn't start until 4000 rpm, then it probably isn't a rod bearing.

Sounds like a stock replacement bottom end would work fine for you.

The motor only knocks when i get on it or when i rev it in park it starts to knock.
not sure what rpm it starts. I have been told i blew a rod bearing

 

[N8Dogg98]

Not sure what your plans are, but I'd go find a Mark VIII short block from the local junk yard, have valve reliefs cut into the Mark pistons and run some nice high lift cams. High compression cammed 4.6 FTMFW

You already have most of the parts there to do this swap, and you'd benefit from the lighter aluminum engine block.

 

[Rejekt]

If you're not looking to do any FI or heavy mods, a stock replacement rebuilt motor would be good for you.