effective stack size: 400~~
utg open to 8, fold to hero in bb with KK 3 bet to 25, utg flat.
utg is a super loose preflop player can open anything from any pos, hero tag.

flop: 9T4 (51)
hero cb 30, villain call.

turn: K (111)
hero check, villain bet 70, hero call.

river: Q (251)
hero check, villain allin 235...

hero???
thoughts on hero turn play also?

The Q isn't such a terrible card. It blocks QJ, and he's not likely to have backdoor spades. He doesn't bet the turn with many J's (doubt he bets JT, J9, etc). You bock KJ. I think his most likely value hand is QJ, but he can certainly overvalue worse or bluff with something like 87 often enough you have to sign call this off getting > 2:1.

A better read would be pretty helpful.

Bet the turn.

plan vs this villain is to make a value hand and bet-bet-call-raise!

pf: might go 32-35.
flop: bet 3/4 pot / fold to raise. as stated, lead 50 into 70, he calls, pot is 170. 315ish back.
turn: yay. fire 125 into 170, obv calling a shove. pot's 320, 290 back.
river: shove any river due to pot size.

i'm not happy on the flop
i'm very happy on the turn
by the river it's too late and i gii.

vs a player as described, i'm leading the turn and getting calls from a wide range, as these guys will never give you credit for a hand, or they get married to their weird two pairs, as you obviously have aces. With the stack sizes, once this turn play goes off, the river plays itself, and you are making money vs his range.

on the turn as you played it: b/c >> c/r >> c/c

my only caveat:

there are players who will open wide, play the flop wide, but are fit/fold on the later streets (meaning they only continue with a value range). Then there are other lags that are actually laggy through all three streets. Just because one is "super loose preflop" doesn't mean anything about their tendency to continue on later streets. What has been happening with this guy on the river? Does he not get there / only show down value hands? Or is he equally loose on the river?

If the player is of the first type...well, we can weight him towards more nutted-type hands like QJo (although does he really call that pf?)

The second type of player, who is truly loose on all streets and "tries to pick off weakness" is going to take your two checks as WEAK and make moves. Yes, he could have AJ/QJ, but TT/99/44 is in his range and you 3b and then seemingly gave up on turn and river. I think reads of the player type make the difference here..