thermostat ?

[briggie]

i went out in my mistral tonight and it seemed to take ages for the windscreen to clear enough for me to see out of , even with the aircon on it wasnt really clearing the screen .... temp gauge was hardly off the bottom , and vents where only blowing warmish air .... so i took it for a run on the motorway and thrashed it ...... no difference .... so im thinking the thermostat has stuck open ..... am i correct in my assumption ?

 

[lacroupade]

i went out in my mistral tonight and it seemed to take ages for the windscreen to clear enough for me to see out of , even with the aircon on it wasnt really clearing the screen .... temp gauge was hardly off the bottom , and vents where only blowing warmish air .... so i took it for a run on the motorway and thrashed it ...... no difference .... so im thinking the thermostat has stuck open ..... am i correct in my assumption ?

well some say it should fail in the open position, but I've had it fail both ways, over and underheating, but its the first thing to check...should be cheap and cheerful and 3/4 bolts max.

 

[ssteve]

i went out in my mistral tonight and it seemed to take ages for the windscreen to clear enough for me to see out of , even with the aircon on it wasnt really clearing the screen .... temp gauge was hardly off the bottom , and vents where only blowing warmish air .... so i took it for a run on the motorway and thrashed it ...... no difference .... so im thinking the thermostat has stuck open ..... am i correct in my assumption ?

yes

ssteve

 

[bailey]

yes it can stick open , this happened a couple of weeks ago on mine , would not warm up . Put a new thermostat in and its as warm as toast now

 

[clivvy]

didnt Rick replace it though, |Pete?

 

[briggie]

didnt Rick replace it though, |Pete?

yes , but i guess they can fuff up..... coolant level is ok ( above the fins after i lift off the rad cap ) ...... its the only thing i can think of

 

[clivvy]

seems to be, cheap and very easy to replace at least, so if it does turn out to be something else, no harm done

I got mine from Andrew Pages, about £12 it was but i bought some coolant as well as I needed some at the time. didnt take long to replace either.

 

[briggie]

am i right or wrong in thinking that if i disconnect the top rad hose and put a hose pipe through it , then disconnect the bottom rad hose it will flush out the system including the heater matrix ?

 

[clivvy]

am i right or wrong in thinking that if i disconnect the top rad hose and put a hose pipe through it , then disconnect the bottom rad hose it will flush out the system including the heater matrix ?

nope.

all you will do, is flush the radiator out. The only way to empty and flush the system, is to undo the wotsit under the engine to drain the system (i think that does the matrix too) then as you say, hose pipe in the top, till it drains clear out the bottom...apparently, the wotsit (drain plug) is an arse to get to....

 

[maverick-matt]

or take the thermostat out and test it in a boiling hot glass of water to see if it opens and shuts

 

[briggie]

or take the thermostat out and test it in a boiling hot glass of water to see if it opens and shuts

hmmm .... nice idea , but me and a glass of boiling water .... hmmm

 

[briggie]

im just gonna try and stick another stat in , cant be too difficult surely ?

 

[lacroupade]

im just gonna try and stick another stat in , cant be too difficult surely ?

for the sake of £12 could you be bothered? Boil the kettle but only to make a brew for when you've spent five minutes changing the stat :thumb2

seriously it should be three 12mm bolts, tap the housing to free it off, remove old stat, drop in new one, plus new gasket, retighten three bolts....job done.

Oh and top up with fresh antifreeze...

 

[briggie]

for the sake of £12 could you be bothered? Boil the kettle but only to make a brew for when you've spent five minutes changing the stat :thumb2

seriously it should be three 12mm bolts, tap the housing to free it off, remove old stat, drop in new one, plus new gasket, retighten three bolts....job done.

Oh and top up with fresh antifreeze...

and celebrate by drinking said cuppa :thumb2

 

[solarman216]

Yes Pete you had a new one fitted, and I have to say I have never seen a wax stat fail open, if the wax leaks out it will not operate and the spring holds it closed, to fail open it has to jam up, I suppose it is possible but I have never seen it, if any one knows better or can explain to me in detail how a wax stat can fail open other than with some debris holding it open I would like to know I understand that some very clever things can be done with "memory metals" but am unaware that has been applied to car stats, Rick

 

[rustic]

Yes Pete you had a new one fitted, and I have to say I have never seen a wax stat fail open, if the wax leaks out it will not operate and the spring holds it closed, to fail open it has to jam up, I suppose it is possible but I have never seen it, if any one knows better or can explain to me in detail how a wax stat can fail open other than with some debris holding it open I would like to know I understand that some very clever things can be done with "memory metals" but am unaware that has been applied to car stats, Rick

My thermostat on the outboard engine is a wax stat, and that often fails open.

Usually after a good run in the summer, a bit of debris ( aluminium oxide/ limescale) jams open the stat. Of course due to the cool running it can no longer get to a higher temperature to dislodge the debris.
I open the stat housing, press in the spring to dislodge the crud, rinse and refit. 5 minute job usually once a season.

However:- have replaced the stat before due to overcooling, and there was no debris at the time ! I wonder if the wax changes characteristics after so many cycles, like the old bubble lamps you used to get.
Eventually the wax no longer forms blobs, or water has affected the wax over time.

As a result the stat opens earlier?
Pan + boiling water + stat + thermometer, only sure way to test them.:thumbs

Ok why do people change thermostats then,
usually because the engine is running too cold,
or due to overheating..:nenau :nenau

 

[lacroupade]

My thermostat on the outboard engine is a wax stat, and that often fails open.

Usually after a good run in the summer, a bit of debris ( aluminium oxide/ limescale) jams open the stat. Of course due to the cool running it can no longer get to a higher temperature to dislodge the debris.
I open the stat housing, press in the spring to dislodge the crud, rinse and refit. 5 minute job usually once a season.

However:- have replaced the stat before due to overcooling, and there was no debris at the time ! I wonder if the wax changes characteristics after so many cycles, like the old bubble lamps you used to get.
Eventually the wax no longer forms blobs, or water has affected the wax over time.

As a result the stat opens earlier?
Pan + boiling water + stat + thermometer, only sure way to test them.:thumbs

Ok why do people change thermostats then,
usually because the engine is running too cold,
or due to overheating..:nenau :nenau

well as I said earlier, I've had them fail both ways...the last one failed open and I was getting serious underheating!.:nenau

Failing in the closed position is a pretty dumbass thing to do really if you think about it....at least you can get home and there are no serous repurcussions if it fails open...failing shut means overheating very quickly...how duh is that?

 

[solarman216]

Well sorry gents but unless you can show me the mechanics behind a stat failing OPEN other than some crud holding it that way, then I stick by what I say they have to fail closed, like what mechanism can hold the stat open against the spring??, old stats were of the bellows type, the bellows naturally sprang open it, then had some alcohol sealed in it and only when it got hot did it open, if the alcohol leaked out it sprang open, fail safe, now there may be something in modern stats that I am unaware of, but until I know exactly what it is, I remain of the opinion that they FAIL CLOSED, Rick

 

[JimmyJaffa]

Have to agree only foreign matter to keep it open, always found stats to fail in closed position never found one jammed open in 18 years of being mechanic:nenau Always have to remove center as a temp repair.

 

[clivvy]

Pete, buy a new one just in case, but im still reserved about it failing-Rick fitted a new one, im certain they last longer than this. My worry is you keep topping up the coolant, so unless this is due to a failed thermostat and water is leaking out the housing perhaps?

anyway, £12 gets a new thermostat and 5 easy minutes to swap it. I fitted my new gasket too, didnt have one on the old one, but i had to cut mine to shape as it was some sort of universal gasket...