looking down a ca18det spark plug hole...

[Dan1200sss]

is it normal to see some kind of oil/fuel residue on top of the pistons on intake side of the piston if you look down the spark plug hole of a mint running and rebuilt ca18det (when its not running tho obviously) ? its running great and never smokes. ever. opinions? is this fine and im worrying over nothing?

[mdb4879]

if i had to take a guess i would figure its normal. i've never actually looked for that myself, but i know when you shut down your engine the fumes from left over fuel will create a residue in your intake, particularly near the ports, so if the motor is stopped in a position where the intake valves are open on a cylinder then that residue could build on the tops of the pistons. or so i would think. (this may be something carburated motors do that FI's dont because the fuels travels the whole length of the intake, but i can't remember now because it seems like the last time my stepdad had the head off of one of our 3rd gen preludes it had fuel residue along the intake)

[boost_boy]

is it normal to see some kind of oil/fuel residue on top of the pistons on intake side of the piston if you look down the spark plug hole of a mint running and rebuilt ca18det (when its not running tho obviously) ? its running great and never smokes. ever. opinions? is this fine and im worrying over nothing?

As long as it's not excessive wetness or even smoking, but still would mean that you're possibly over-fueling or oiling. it should be somewhat dry in the combustion chamber and on the crwons of the pistons. So if it's very wet, it's okay to be concerned because that concern would be legitimate.

Causes could be:

Leaky injectors

Poor oil control

Leaky headgasket

Weak ignition

Rich or overfueling condition