Should the top of my piston be rough!?!?!?!

[Blakedude409]

I took off the head on my 2.5 and i noticed that thr top of my piston was rough to the touch, it wasn't smooth like the inside of my sleeve. The reason i took it off was because when i took out my glo plug the filament was all broken and smashed. Please help me, i dont know whats wrong!?!?!?!

thanks in advance

 

[Çh®i§tiªñ]

Well if its rough in the area where the plug would be located, then you have a problem.

1. You are running plugs that are too long.

2. The piston rod could be spent. If the piston rod starts to go it will almost stretch and start to bang into the plug.

Check to make sure you arent running the wrong plugs first. Then, if anything, try a shorter plug like an O.S. R5. If you here it 'ping' when you go to start it with the R5, STOP! Take out the plug and begin and engine tear down. Start with just taking the head off and rotating the flywheel. If the piston comes up to the top edge of the sleeve, or worse yet, above it, then you know its going to need to be repaired (in a majority of these cases).

Let us know where you end up and we should be able to point you in the right direction from there.

 

[FastEddy]

Is it pitted or does it have a buildup on it?

 

[Blakedude409]

Come to think of it, i think it has build up.
Oh yeah, i am using mcoy 59's or mc-59 strongly recommended by my lhs.:yes: but it smashed the traxxas plugs too .

thanks for the quick replies

 

[FastEddy]

Can you post a pic of a smashed plug?
A pic of the top of the head would help as well.

1- you may have a huge amount of buildup on the head.
2- worn parts on the inside may be letting the piston extend to far.
3- I forgot, Does the 2.5 use head shims? Someone help me here..

 

[Blakedude409]

I think i fixed the problem, i switched to a shorter plug. I have been runnin all day and i havent had a problem.:bling:

thanks a lot for the help!!!:cheerful: :bow: