I'm just wondering, is anyone out there running without a thermostat? I just recently got myself a '94 del sol S. The temperature gauge barely makes it up about a notch over the "C" and that's with driving 80 mph on freeway for about half an hour. Heater blows pretty warm air, not hot, but enough to warm me up. I thought it was possibly a stuck open thermostat. So i decided to change it. When i took off the thermostat housing, i noticed there wasn't even a thermostat. So i put one in. Filled the radiator up (i drained and flushed) and started the car. In park, the car was revving itself, like it was bouncing between 1000-1500 rpm. It would only do it in park or neutral. When i would rev it out of the 1500 rpm range, it would go away but as soon as i left off the pedal, it came back. When i would put it in gear, it would go away. What would be causing this? So freaking out, i turned the car off and took off the thermostat. Putting everything back together and started the car up again. I noticed immediately that the temperature gauge rose up to about a quarter to a third of the way up. Heater was turned on full blast, with the heat all the way up (blowing cold), the car was still self revving until i guess it warmed up. I drove it around for a while, came back and the temperature needle dropped back down to just above the "C" again. I let the car sit overnight and started the car up again to see if it was self revving and it was gone(seemed like it was doing it when it was cold). So i have yet to put the thermostat back in to try and wait till it's warmed up and then see how it goes. I guess my questions are, has anyone else had this happen? Normal? Abnormal? And yes, i did get the right thermostat and use the right gasket, i followed everything in the shop manual. Oh yeah, i've also noticed that my gas mileage sucks. Granted it's better than my '73 roadrunner, but i'm only getting 208 miles on average city driving with the car tuned up, new O2 sensor, basic intake, header, exhaust. My theory is that when the car is cold, it uses more fuel, if i run without a thermostat and my gauge stays just above the "C" all the time, meaning it's cold, would it use more fuel? Hence the poor gas mileage? Well sorry for this being so long, just wanted to as well as i can describe my dilemma so if anyone can help, i'd apprecaite it, thanks.

 

Cold engine = poor gas mileage Use the proper thermostat.

Are you sure you purged all the air from the system? An air bubble might cause the TW sensor to misread and upset the idle.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Perfectionist &raquo;</TD></TR><TR><TD CLASS="quote">Cold engine = poor gas mileage Use the proper thermostat.

Are you sure you purged all the air from the system? An air bubble might cause the TW sensor to misread and upset the idle. </TD></TR></TABLE>

Ditto.. Plus when you install the T-stat please check that little nipple thing on it.. make sure you install that with the nipple on the top part. it is an air bypass so you can bleed the system faster.

 

did you reset the ecu after you installed the thermostat??

if your car is used to running without a thermostat and then you put one in...the computer needs to "relearn" .

if you didn't do that...try it. Let the car idle after you reset it for about 5-10 mins and don't drive it hard at first....my car always acts funny after I reset it. Usually will rev weird, and it evens dies at stops until it understands whats going on....its adjusted after I drive about 2 trips.

but you shouldn't be driving around without a thermostat...

 

the revving is because you did not properly bleed the cooling system. Open up your radiator cap and leave it up untill all the air is bled. Also make sure to have the heater on full in hot.

 

I ran without a thermosta because I was conviced it was the source of my problem, but low and behold, I had a baarely leaking headgasket. I put the thermostat back in but still had problems but I lived with it... lucky for me the headgasket finally blew only after returning from a 14 hour roadtrip. wheeeew! that woulda SUCKED

 

Ahh, i didn't purge the air. Ok. I think i got the right thermostat, 180 degrees right? Thanks for the quick replies.