1997 civic ex coupe 210,000 miles
little unknown history just purchased few days ago
owner had put new dizzy cap and rotor button on it because of occasional stutter

the car will run slightly higher than normal temperature and sometimes spike to about 3/4 way to the H the come back down to normal. never runs half way like every other civic Ive had

no check engine light

I put a new oem thermostat in and made no difference

checked coolant and its full

did a compression test thinking head gasket may be blown

cyl#1 150 cyl#2 155 cyl#3 150 cyl 4 couldnt get the darn plug out it was super hard and didnt wanna strip anything.

Ive noticed NO power loss except a very seldom once in a while stutter or miss

just drove it 5-10 miles and it stayed around here

it will gradually rise above what the pic shows and then drop back down



it will usually stay a little bit lower than that but def above the middle where its supposed to be

there is no smoke at all except a very little black puff under 100% acceleration from a stop

so could the water pump be acting crazy?
is there a way to test it?

whats my next step here

 

Did you check the fan function? Burp the cooling system?

 

Yes i did

 

Did you do a tune up and replace thermostat, water pump, timing belt and tensioner?

 

I haven't done any of that yet except for the thermostat if you think a water pump and tensioner would help I'm going to do it and a timing belt

 

Before throwing parts at it make sure the fan functions and the fan switch is still operating. I would also pressure test the system to see if your losing any coolant. It is possible that the headgasket is slightly leaking.

 

If you dont know anything about the vehicle ie. The ladt replacement interval its prolly a good idea to plan to do the water pump/timing belt anyway

 

Kudos! That's the first solid piece of advice i've seen you give!

 

With 200k miles and no way of confirming if the timing belt was replace I'd get the **** up all in there and replace what I can.