Running with no thermostat ?

So this weekend I changed my radiator and thermostat. Problem is when I went to remove my old Thermostat, it did not have one? All it had was a the O-Ring and a piece of the Thermostat. I installed a New Thermostat had a problem, it over heated instantly. So I removed the new one, put the old one back (which is just the top piece where the O-Ring goes on) and put a new O-Ring on it. Temperature now is leveled and fine. So my question is, is it bad to be driving without a full Thermostat?

 

Yes, it is bad. You can actually cause overheating w/out a thermostat - coolant does not dwell long enough in the passages to gather heat, so it carries away less heat, causing complete overheating or hotspots (even worse). The chunk of thermostat left behind may be slowing the coolant flow enough to prevent that, but I would not want to bank on it.


If you overheat with a proper thermostat (test the new one in some boiling water, just to be sure it's OK), then you have other, bigger problems you need to address ASAP.

 

So far it hasn't overheated without the thermostat like shown on the picture. The mechanic who first changed my tstat removed because he said it kept overheating with it on. So you're saying the rest of the tstat is in the tstat housing? Because I didn't feel anything in there.

 

Where did the guts to the old thermostat go? I assume the spring valve came undone, but is it lodged in old radiator? I would want to know where that went. If it's stuck somewhere it may be causing flow problems. I recently put a Stant 170F in my 3.4 and it works great.

 

I hate to be all doom-and-gloom, but my guess is those parts are lodged in your engine somewhere by looking at this diagram.



I would find out what happened to the old thermostat guts before going further to prevent this from happening (worst case)

thermostat-fell-apart-caused-overheat