P0308, Bad Compression

[brendan127]

It has 25psi compression, and 99% leak down on #8.

So what is needed to fix the car when it drops #8? I was quoted $9800 from brenspeed to fix it and I'm not interested in going that route, because I want to trade the car in at some point.

Is it able to be fixed by just replacing the rings, and maybe the piston? If the cylinder wall is bad couldn't that just be sleeved?

 

[stkjock]

motor needs to come out and be rebuilt


if you can do a swap, finding a junkyard motor would be least costly way

 

[weather man]

Fleabay motor swap be cheapest.

 

[brendan127]

motor needs to come out and be rebuilt


if you can do a swap, finding a junkyard motor would be least costly way

But why? What's keeping it from just being able to change the rings? Because it runs fine aside from pouring smoke out.

 

[brendan127]

A junkyard motor is still 4-7k which is too much.

 

[travelers]

It could also be valve seals.

 

[brendan127]

It could also be valve seals.

Bad valve seals on a 27k mile 2012 mustang? That's known for #8 to go bad?

 

[LarryJM]

I have seen some bad #8 pistons and they do look sad. What?? white smoke, black smoke, blue smoke? Truck engines seem to be 1/2 Mustang engines at junkyards. I found a 10K mile example for $2000. For sure it can't be fixed in the car.

 

[stkjock]

But why? What's keeping it from just being able to change the rings? Because it runs fine aside from pouring smoke out.

I guess thy could possibly pull the rod and piston from the bottom, but it’s rare that it can be done

 

[Gabe]

Built short block ...

 

[travelers]

Bad valve seals on a 27k mile 2012 mustang? That's known for #8 to go bad?

Yea on second thought the compression wouldn't be low. Brain fart......

 

[Marble]

There could be all sorts of carnage and until its torn down you will never know. I thought I had only a bad thrust bearing, but the bad bearing ended up toasting all but one rod. The crank shifted and ruined the block... etc etc.

Point being you never know what is really wrong until its torn down. By going the route of only replacing rings on #8, I would almost guarantee the cylinder needs honing and ot would not work. Cheaper would be more expensive in the long run.