when to jam vs 80/28/1.7

[RiverFenix]

Villain and i have been battling a lot. Hes sucked out a ton on me on the river. No real reads. He has had a decent amount of bluffs and value bets/raises on the turn but havent seen him bluff the river more than once.
Im running at 31/16/2 or so.

.5/1 6max
Villain is in BB w/ $180
Hero has 54 [img]/images/graemlins/club.gif[/img] [img]/images/graemlins/club.gif[/img] in MP. Hero covers

PF: fold, Hero raises to 4, folds, Villain calls in BB.

FLOP ($8.5):6 [img]/images/graemlins/diamond.gif[/img]7 [img]/images/graemlins/spade.gif[/img]K [img]/images/graemlins/club.gif[/img]
checks, Hero bets 7, SB folds, Villain calls

TURN ($22.5): 8 [img]/images/graemlins/diamond.gif[/img]
check, Hero bets 16, villain raises to 32, Hero calls(?)

RIVER (86.5): 4 [img]/images/graemlins/spade.gif[/img]
Villain bets 18, How much?


Villain can easily have 95 or T9 here fyi. Since hes betting the river I'm assuming hes not bluffing so he probably has any 2pr, straight, set. One pair type hands are most likely out unless its AK.

I know I should be putting in more money on the turn if I want to try and stack him but w/ him having the initiative I didnt expect him to bet so small on the river. If I 3bet turn, how much too?