Hi!! I have a 2000 LHS with a 3.5 motor and need help locating t-stat.
Looks like it is under the air intake and may need to remove i think.

Seems to run hot at times on a 3 hour trip. Temp. will be ok for a while and then gauge will go up to neer the red area and sometimes will go back down to around half way on the gauge.

 

chk your fans first and the t stat is on the driver side behind the alternator.

 

Fans working fine, replaced both fan relays just to be sure. Will replace t-stat this weekend.

What type of antifreeze should i use and what is the best way to fill the coolent system and bleed out any air?

 

I doubt its a t stat if the fans are working and U dont see any leaks more then likely head issues the 3.5 has been known for it.

 

I don't mean to scare you...but it does sound like head gasket...have pressure test done. Mine is getting new head gasket as we speak... Mine kept overheating periodically so I replaced t-stat thinking that is what it was...but I went and head pressure test to be safe and glad I did...saved my motor!