Thermostat replacement

I am wondering if my 180° Thermostat is not long in the tooth... about 2.5 years old.

I am seeing the temp go thru various excursions from the middle of the guage
on one day to 2/3 of the way to the top the next day.

Holds steady for the trip, but isn't always in the same spot as before.

Until recently it was rock steady at the 2/3 position.

Oil and Coolant are OK.

Seems to run cool on hot days (1/2 way position) and hot on cool days (2/3 way position).

Is this indicative of the thermostat going belly up soon ?

Bought another one just in case....180° (easier on the engine).

BTW - just have to rub this in.....got 50.3 mpg on a tank of Shell Gasoline today (calculations).

HOT DAMN ! Beat THAT you stinkin' hybrids!

Take note of that, Obama ! Have GM make more 1993 1 liter Geo Metro's !...and don't screw around with them, either....

Filled with COSTCO gas today - will see if brand of gasoline makes much difference.

DoctorBill

My MPG's can jump almost 10 depending on the brand or octane. I run premium fuel only and the Sunoco 94 is really good. Shell gasolines seem to hurt mileage and performance for some odd reason.

hi bill,

will be interested in your results. my old thermostat was rock steady for at least 250k and then when i had the fan / radiator problems, i also replaced the thermostat and it makes much larger swings through a different range. a mechanic friend says that non japanese replacements are never calibrated as well as originals. i'm tempted to put my original thermostat back in.

it sounds like cool days produce engine temperatures insufficient to trigger the fan ... and the hotter days might cause the fan to run intermittently and keep the coolant temp lower. you'd still see a slow / initial swing in temp indications on the gauge i think.

i've run mid range fuel for most of my metro life. cumulative avg on new engine 51mpg .... high of 68.5mpg.

I've never seen a Metro temperature gauge anywhere but dead center and dead steady. From over 100 degrees with the A/C on full stopped dead in traffic on a black road to 0 degrees with the heater on full at 70 mph on the highway. Five different cars and over 650K miles, never seen one move unless something was wrong.

I just asked a related question in another post before seeing this. Both of my 1991 Metro's without EGR will go almost up to 3/4 before the fan kicks on. While driving normally it usually stays in the center. I just replaced the temp switch on the intake with the same results.

hi doug,

i agree with you re the swing of the gauge. most of the time the gauge was dead center but it did change. what you describe sounds normal to me but once you get a sense of the 'normal' for your system, it's always worth watching for further changes. i think my fan cycled more as the miles built up and now i'm trying to get a sense of the new engine's and cooling system's qualities. if i can believe my gauge, i think it's now running a bit too cool overall since the gauge swings between 1/3 to almost 1/2. i may actually put the old thermostat back in.

if i read woodie right, his gauge never swings at all. this makes me wonder if his fan ever comes on? if it does, then at what temperature? he seems to be suggesting that the temperature difference between 'normal' and the temp at which the fan comes on is so small that his gauge doesn't detect it. my gauge always seemed quite sensitive ....... and system and environmental differences made slight changes in the range and duration of the gauge swings. i think the integrated multiple sensors and computer compensations are quite sophisticated and it may be that woodie's systems are accurate and functioning optimally and they keep the temp in a very narrow range. that certainly seems desirable.

redpepe: Your new engine may have one of the 160F thermostats in it. I had one that would do just like you described but I went back to the stock thermostat this past winter.

thanks doug.

the thermostat had been replaced a few months ago along with almost all of the cooling components. i can make every mistake possible so it could be a different from orig thermostat but i've kept everything stock as far as i know. a poorly calibrated thermostat could produce the same results but this is hard to prove immediately. not sure how the various components would concertedly respond to a lower temp thermostat.

quick update on the rebuild. i replaced the new head gasket and 'check valve / restrictor' yesterday and there's significant improvement in the 'oil pharting'. some more miles may help the still significant blowby but at least the pooling of oil in the valve cover baffle seems to have lessened. even above 65mph the emission seems to be only collected oil vapors ... mixed with some water vapors from blowby i think. i opened the 2 upper gasket holes to match the porting. hope to post some photos soon.