Heads Are Off.........images And Thoughts On Piston

Discussion in '1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-' started by from6to8, Jan 19, 2014.

  1. Took the pass side head off today, the one with the broken spring at no. 2 cylinder. Images below let me know what you guys think about the piston head 1.jpg head 2.jpg head with valve look.jpg
  2. Piston will have to be replaced
  3. I think now is a good time to just pull the whole thing and rebuild. wouldn't cost you that much more and will give you a good chance to change out other things that are a Pita like the oil pump. and you can check/ replace the other bearings in the motor.
  4. If you put a new valve and spring in it and put it back together it will run. I dealt with that many times as a mechanic, especially on cars with timing belts. I would lap the valve in with over the counter valve grinding compound and then compression test it when it was done. I was often amazed to find that the cylinder I did the valve job on myself ended up having the best compression out of all four. It's not going to be optimum for performance with a piston like that. I seriously doubt it's done any serious damage to the piston other than what you see. The piston is far stronger than the valve, and the valve stem ends up giving out way before the piston gets a crack. The only real threat you are going to have is carbon build up on that piston leading to detonation. I'd give it a 75/25 chance that if you put it back together without changing the piston, you'd never notice.

    88LX5.Oh and 90lxcoupe like this.
  5. just a little slap and tickle. People have done far worse to motors and had them still run. If money is tight right now, I'd put money into the head to get it right. The piston should be fine.
    krazedstang and 90lxcoupe like this.
  6. That's the big one. How much money do you have to spend right now? I'm sure that piston can be repaired. I know it would cost about the same as a new piston, but that one is already broken in with the engine, and is going to seal fine with no block machine work. Pull the valve out of the head and check the seat with your fingernail. Run your fingernail around the valve seat. If it catches anywhere, it's most likely going to need a professional valve job. If not, then it can most likely be lapped in just fine with valve grinding compound; which is basically just to match a new valve to an old seat.

    A5literMan likes this.
  7. unless its a power adder car i'd leave it alone...
    f8tlfiveo likes this.
  8. its obvious that the piston has been dinged, but i dont see any damage that would cause any concern. unless you see a crank in the piston top, leave it alone, repair the issues with the valve, and put everything back together and run it. i agree that as long as you dont have a power adder, or are trying to make more power than the components could hold when new, you are good to go.
    NTO_GUY likes this.
  9. Make sure there are no sharp burrs or protruding material from the piston, as this could act as a glow plug and cause detonation/pre ignition. It looks like you should otherwise be ok with a new valve and spring.
  10. thanks to all that replied. I'm just now getting to reply as my notifications didnt alert me.

    yes talking to some people they echoed the same thing most of you said. I am going to take the heads to the shop and go ahead and get a set of new, upgraded TF springs just to be safe safe because something caused that one spring to break and i mite as well just upgrade all and let the machine shop put in a new valve.

    I will clean up the scrapes on the piston and clean up the block and pistons good.

    A few questions I have:

    can a 6 or 12 point socket be used on a hex head bolt?

    can the dowel pin things on the heads be used again to align the heads again to put on the block?

    i just fixed the intake gasket a few wks ago with felpro 1250 s3. Can they be reused?
  11. Yes, you can use a 12 point socket on a hex bolt. The head dowels can be re used so long as they aren't too corroded. They should fit snug. Not sure about the intake gasket.

  12. You have already said it, but I would sand the piston and clean up the sharp edges.

  13. Run it. I've run much worse on several cylinders.
  14. Don't reuse the intake gasket. Get a new one.
  15. the dowels just push it/knock in and seat ?
  16. The dowels normally stay in the block. If they're in the head, remove them and tap them back into the block before putting the head back on. Just make sure they're not mangled or marred up.
  17. dont try to pinch pennies reusing any gaskets, unless they are a proper copper or aluminum gasket, or you will have leaks.
  18. I'm a bit curious here. The cylinder in question has a clean surface relative to the others. Also, the coloring on the valves for that cylinder are also different. This was a catastrophic failure that happened suddenly. How would it account for the significant difference in the deposits?
  19. i wonder if my car's changes in how it drove from time to time had anything to do with a possible gradually worn , loose spring or something that started out as slight enough to cause changes in how the car drove but not bad enough to not cause anything too bad until receently the week of thanksgiving and to your point of what you just said? Ohh maybe it was me putting in the laquer thinner in the no. 2 sp hole in trying to see about decoking that cylinder as part of diagnosing an improper seating valve. Also this guy told me about the trany fluid/premium gas mixture to try and tried that also

    hmmmm, i really wonder? That's why i'm going to change all the springs and not just that one that broke but maybe it was the laquer thinner that cleaned the piston up