For it's cost, I'd suggest some improvements.
3+ Armour save.
Steam Burst should cause more hits, at less strength but with no armour save. Say, d6 at strength 2 with no armour saves.
For Kick, I'd say it does a strength 5 impact hit per rank.
For Large monsters, I'd suggest doing a few more attacks. I assume the final model will have arms or appendages, have it flail at large things with them.
For Argh! Da floor is movin' boss, i'z is feelin' a bit woozy!, I'd suggest making it move d6. On a hit, it loses the large target +1 to hit bonus due to a maniacal dancing which would make it harder to hit.
Quik, pull dat sprocket, da wata iz gettin' noizi!, make the steam hits give no armour save, and strength 2.
Also it should clearly cause terror.