Dead Cylinder, need Help!!

[blkhwk7]

First of all hello everyone. I joined this forum to try and figure out how to fix a friends 1999 Explorer with 4.0 sohc. It seems that something fell in the motor while he was changing his O-Ring gaskets on the injectors. Started the motor and heard a rattling sound. He took it to a shop and they told him he had a hole in the piston. I did a compression check and found Cyl 2 to be "0". My question is can the piston be replaced without pulling the engine? This is assuming no damage had happened to the cylinder. Engine has 130K miles on it. Was thinking might be able to drop the pan and do piston from underneath.

Thanks ahead for any help.

Jim

 

[wildbill23c]

I think in order to get to the pistons to get them out you have to pull then engine and disassemble it. Not sure how else you would get the bolts out of the bottom end of the piston that's connected to the crankshaft without disassembling the whole engine.

Considering something was dropped in the engine you would be wise to tear it down and check everything and make sure you get whatever fell in the engine out so it don't cause any other damage.

 

[blkhwk7]

BTW this is 2wd. I figured if I dropped the pan I could get to the piston by turning the crank.

 

[adsm08]

If you completely remove the crankshaft you could probably take the piston out the bottom. You would have a hard time putting it back in though. It pretty much HAS to go in from the top. That means pulling the head. Since it is on the right side and we are dealing with a SOHC that means pulling the engine.


Just for fun, here is a pic of a cylinder that got a hole punched in the piston when the exhaust valve dropped.



The dark spots are damage to the block where it got hit. If it went in the injector hole it wasn't as big as a valve, but it could still have done damage to the cylinder wall. Also, to punch through the piston it has to be big enough to touch the head before the piston gets to the top. Similar to a valve.

Here is the head from that cylinder.



Don't think for a second that you won't need a new head.

 

[RonD]

Yes, you would have to remove the crank to pull piston out the bottom, for sure not enough clearance otherwise.

Nice pics ........ahh the good ol' days of carbs and that big hole to drop stuff in


You could pull the head on the one side and oil pan, remove and replace piston, that wouldn't be too bad on a 4.0l OHV..........

But because of the SOHC setup you would be better off pulling the engine, the timing chains would be the biggest pain.

Shopping for a used engine at this time wouldn't be unreasonable.

 

[adsm08]

Shopping for a used engine at this time wouldn't be unreasonable.

I would have said it'd be recommended rather than not unreasonable, but yeah, that's where you need to go.

 

[RonD]

Yes, probably so, after pulling the engine and the head, you may need another head, if piston has a hole then head is probably too beat up for repair, it is an aluminum head on those engines if I am not mistaken.

Replacement head would be $400-$500, plus piston, probably two valves and all the gaskets and time to do it.

Used engine would run $600-$1,000, I would replace the timing chains and guides, that is a weak point on these SOHC engines

 

[blkhwk7]

Thanks for the input. Looks like it replace the engine time, is there anything besides the timing chains to look out for? I assume its pretty much a basic R & R

 

[adsm08]

Chain tensioners. Those are why the chains go bad.