xj wont warm up

At the end of the summer i switched to an open cooling system on my 87 4.0 after blowing two bottles over the summer. I constantly was overheating. Now the truck is running too cold. I cant get the guage to read past 120-130ish even after driving it for 30min (thats about my longest trip). I dont really trust the guage but i know its running too cold because the heater doesnt get more than luke warm. Its getting cold at night and luke warm really isnt cutting it. Also i open the hood after driving it and the engine really isnt all that hot. At the time being i have no electric fan because i never reinstalled it after converting radiatiors and heater switch ect. One thing i did not change was the tstat. Im assuming the thing is stuck open. I still have the tstat and housing that is for the 87 closed system. Is there a difference between persay a 93 tstat and the 87?? Its too cold to check the hoses right now so im gonna give them a few squeezes tommorow to see if its closed. Has anyone run across this problem? All help would be appreciated

-Mike

I believe the only difference in the tstat housing is the extra bung for the coolant temp sensor. I'm voting for a bad thermostat.

x2 on the stuck thermostat

My vote is its probably stuck open. I had the same problem on our Volvo S60....the check engine light even came on eventualy. I replaced the t-stat and enginge warmed up like it should.

- Joe

well im going to replace the tstat today. What i was really wondering is if the tstats are different considering the difference in pressures between the two systems. Im going to pick up a tstat for a 93 or so just incase because the current tstat is under six months old. Thanks for the replies

-mike

t-stat definitely gets my vote