Hey all, Happy New Years and all that good stuff...

Well, I drove my ZJ today after replacing the t-stat yesterday. Not too good, I'm think'n...

The coolant temp is now reading between 215-218 while driving. It used to run just below 210. I turned the heat on..wouldn't put out warm air unless I turned up the blower motor to high and the coolant temp stayed the same. Got to the store and checked the hoses. Both hoses coming out of the t-stat were hot. However, the small return hose that leads from the radiator cap/radiator back to the reservoir was cold.

Could I have a temp sensor that went south? The sensor in the t-stat housing looked good. No corrosion or anything. The wires coming out of the connector look ok too.

What else can I do to trouble-shoot and diagnose this issue? I would really like to have heat this winter and not cook my engine in the process.

Input and advice greatly appreciated

 

Sounds like your water pump is bad or going bad. The no heat after warm up is most likely a circulation issue, and the rest of what you describe leads me to believe the coolant isn't moving though the system.

 

What t stat did you use. 195, 190, 180?

 

that small hose going to the overflo bottle should be cold that is just for coolant when the system needs more for expanding and contracting or a leak you temp sounds normal as for the heater isuues core could be part clooged

 

mithuth-I thought that too at first but it runs quiet as a mouse, no leaks anywhere either.

541-I got a 195 from Stant

freegdr-cool, that's what I was hoping for.

I just found out ( I hope,) the issue......I had a dummy.....
I forgot to burp the system after installing the new t-stat. I think there may be a bit too much air stuck in there.
I'm gonna go take care of that, right quick like...

 

Good call on burping the system, 195 is the correct replacement although lots of people run 180. The only reason i asked is because the factory T stat is like 192-193ish so if a stat is a cheap or garbage they may act slight different. Never had problems with my jeep t stat but my wife has a civic and ive learned OEM or nothing or that piece of junk, sometimes worth the extra 4 bucks

 

Yeaahhh.....Iiii'mmm a dumb@@$....I burped the system with what I had left of coolant, which was about half a gallon. I can fit more in it. Anyway, I drove to the store and kept an eye on the temp...it came back down to under 210 and the heat nice 'n toasty again.

So, I'm feelin' a bit sheepish about that one! I'll pick up some coolant Mon. or Tues, just to top it off. D'OH!!

 

I always drill a 1/16th hole in my t-stats to allow air to escape and have no need to burp the system.

 

Heheh.. where does the air 'escape' to? Wouldn't you need to open up the system to replace the air with coolant (burping)?
No offence intended, just curious