What's The Right Thing To Do?: Thermostat Stuck After Flushing

[turbocruiser]

H folks, I searched and saw some stuff similar to this but not exactly this. Today (following from the Redline Water Wetter thread) I did a flush and fill on my cooling system. As always I dumped the coolant from everywhere, filled with distilled, dumped the coolant from everywhere again and then started the flush. I flushed and back flushed everything, then I filled with distilled and took the thing to test run. Well about 1.5 miles away and my temp guage starts rising past 90 which is extremely rare with regular use and then to 100 which I have never ever seen and then finally 108 by the time I got through that light and pulled over. I had both heaters on but no heat. I'm sure the thermostat stuck. I simply waited about five minutes, turned it on again and felt for heat but there was none. Then I waited another five minutes and repeated this about four times every five minutes. Finally I waited about twenty minutes and just occassionally turned the key but not the engine to see the temp on the factory gauge and the greddy gauge. The temp never exceeded 108 celcius on the greddy and got nowhere near the red on the factory and from there slowly lowered to 80 at which point I filled up the rad with some more distilled (about .5 to .75 liters) and then drove home the 1.5 miles. On the way home the temp was about 90 and as I pulled into the neighborhood I felt some heat. As soon as the heat came on the temp dropped down to 82 and stayed there.

Soooo, my question is, what is the right thing to do in this case??? Should I have continued driving to force the water pump to open up the thermostat or should I have stopped driving as I did. Is this 108 a real 108 or is it a bubble temp of air in the system??? Is this cause for concern??? Thanks fellas.

 

[cruiserdan]

I wonder if you had an air pocket somewhere. Did you feel the radiator to see if it was hot when the temp gauge was up there?

 

[turbocruiser]

I wonder if you had an air pocket somewhere. Did you feel the radiator to see if it was hot when the temp gauge was up there?

Yes the top of the rad was warm but the bottom was not particularly warm. I tapped on the thermostat housing then squeezed the hose from the lower rad to the metal tube then the section from the metal tube up to the TS housing. Neither of the hoses were particularly warm either. I think the TS was stuck closed. I'm just worried about that temp spike, I would've thought that the jiggle valve would allow enough water past to prevent harmful air pockets? I hope no harm came to the engine!

 

[cruiserdan]

I don't think that a previously perfectly functioning thermostat would suddenly take a s h i t because of a flush. (did you notice that I have figured out a way to defeat the censor? ) . You had to have air trapped in the system somehow....


D-

 

[turbocruiser]

I don't think that a previously perfectly functioning thermostat would suddenly take a s h i t because of a flush. (did you notice that I have figured out a way to defeat the censor? ) . You had to have air trapped in the system somehow....


D-

Okay that's good to know, the TS only has 7.5k on it so its no where near old. So now what I need to know is 108 recorded through an air pocket a problem? I mean I warmed the thing up perhaps three minutes then drove for three minutes then shut down, what's the damage doc???

 

[cruiserdan]

Well clearly your Greedy saw a coolant temp above boiling. I don't think it would read properly unless the probe was imersed. 108c is just a tad over 226f which is the factory A/C cut-out threshold.

I think all it did was scare you bad....

 

[Erratic]

nevermind me...

 

[turbocruiser]

Well clearly your Greedy saw a coolant temp above boiling. I don't think it would read properly unless the probe was imersed. 108c is just a tad over 226f which is the factory A/C cut-out threshold.

I think all it did was scare you bad....

I hope!

So if the two gauges were reading real temps and there was an air pocket somewhere, why would that cause the water to heat to that temp in such a short time? Also, I thought a jiggle valve more or less made this scenario impossible??? I might take the trip to Robbie for preemptive HG repair somewhat sooner now unless this is really no big deal. :whoops: Thanks for the help!

 

[e9999]

if you start from cold and you idle your engine, the top rad hose should stay cold or tepid for quite some time and then after something like 5 or 10 mins -I forgot- "suddenly" go to very hot when the stat opens up at 85C or so (IIRC). It's quite noticeable. And it's hot enough then that you can't keep you hand on it I think. If you don't see this, then yes, it would be stuck closed. You probably also could keep the rad open and you are likely to see a sudden flow of coolant moving around in there when it opens.

 

[cruiserdan]

The jiggle valve only works if you fill the cooling system slowly. If you get in a hurry the valve can't vent fast enough. In addition, if the valve is not positioned close to 12 o'clock it will not vent properly. Knowing you like I do I'm certain that the valve is positioned properly. My bet is you filled the cooling system a bit on the fast side.

 

[turbocruiser]

if you start from cold and you idle your engine, the top rad hose should stay cold or tepid for quite some time and then after something like 5 or 10 mins -I forgot- "suddenly" go to very hot when the stat opens up at 85C or so (IIRC). It's quite noticeable. And it's hot enough then that you can't keep you hand on it I think. If you don't see this, then yes, it would be stuck closed. You probably also could keep the rad open and you are likely to see a sudden flow of coolant moving around in there when it opens.

Right, it always takes about two miles for my Greddy gauge to indicate anything at all flowing to the rad but in this case there was temp recorded on both the factory and the Greddy gauge but no heat from heaters and the temp was too high so I think it either an air bubble, or a stuck TS that would do this. At this point I'm just trying to determine if damage occured. Like I wrote above the thing was only above 100 for about one minute of idling and thirty seconds of driving. AND I'm hoping its not a real 108 as such.

 

[cruiserdan]

226 is when the A/C shuts down........not the patient....

 

[Draken]

So would the way to avoid this....be to "burp" the system? I filled my radiator while the front was jacked up....then I ran the engine for about 10 min with the heater on and the cap off. Afterwards I went for a test drive and monitored my overflow reservoir. No change in levels...so I assumed I had gotten all the air out.

 

[e9999]

anyway, it'll take 10 mins to open up the thermostat housing and plunk the stat in hot water to see if it's OK. Can't do better than that if ya wanna know for sure...

and what's wrong with 108? It's supposed to be able to go over 100... doesn't seem that high so no worries I think

 

[turbocruiser]

226 is when the A/C shuts down........not the patient....

Okay I wont shut down if you tell the temp that is cause for concern - 230 farenheit? 240? more??? Thanks!

 

[turbocruiser]

So would the way to avoid this....be to "burp" the system? I filled my radiator while the front was jacked up....then I ran the engine for about 10 min with the heater on and the cap off. Afterwards I went for a test drive and monitored my overflow reservoir. No change in levels...so I assumed I had gotten all the air out.

I think that is advisable. When I was searching I saw several statements about elevating the front end a little and running without the cap on. When I filled the second time with distilled I ran without the cap on for a few minutes but I was on level ground. I did not fill it fast as such, just with the stream from one of those rectangular distilled water jugs with the pull out spout. Next time I will elevate and wait a while to let things burp and settle. But I really did not fill it fast. I would have thought that any air would have worked its way out while I was running without the cap. I'm a worry wart and I've never seen anything above 100 let alone 108 so I was crapping my cargo shorts. I think I'm okay cause it only hit that temp momentarily. The factory guage only went slightly above level momentarily. I hope I'm okay!

 

[turbocruiser]

anyway, it'll take 10 mins to open up the thermostat housing and plunk the stat in hot water to see if it's OK. Can't do better than that if ya wanna know for sure...

and what's wrong with 108? It's supposed to be able to go over 100... doesn't seem that high so no worries I think

You are correct sir! I might test the thermostat but I'm sure its sound. I just think for whatever reason there was not enough hot water up against the thermostat to open it and too much hot water up against the sensors. :whoops:

 

[cruiserdan]

You are fine........



If you are concerned I'll take that piece of s h i t off yer hands and your troubles are over.....

 

[turbocruiser]

You are fine........



If you are concerned I'll take that piece of s h i t off yer hands and your troubles are over.....

Hmm, when you put it that way, NOOOO I'm not concerned at all!


Wow, yer not just a doc, yer a shrink too!!! That was the most effective therapy ever!!!

 

[Rich]

...I had both heaters on but no heat. I'm sure the thermostat stuck....

Its worth noting that with thermostat open or closed heated coolant still circulates through the heater cores, only the heater valve controls the flow to the heater cores.

Your experience would be consistent with Dan's suggestion that air in the cooling system was responsible for the lack of heater output and the overheating that took place.