ok so yesterday my car was running fine as it could be. toady im driving and the temp will stay at 89C for about 5 min and the jump straight up to 121C. There isnt any smoke coming from the exhaust sys. I tried adding coolant & water and that didnt work either. any suggestions? thanks in advance

 

When it hits 121C, are the fans running? (You might want to pull over to check)

I know that's not a lot of help, but it's a start.

Dave

 

Does the coolant light come on? Was it low at the filler neck or the overflow bottle? How old is the thermostat?

Tim

 

Do you still have stock radiator? i was haven that exact problem the last couple weeks and i got a new radiator and now its not doing it but mine was jumpin to about 110 c so not as high but close. and when i got the stock radiator out i tried cleaning it and was so dirtyand clogged, and starting to rot so you might want to check your radiator if its not allready new...

 

...try not driving it for very long until you find/fix the problem...or you end up rebuilding it...

 

i have a koyo rad. the fans are coming on. and i filled the coolant and water myself after the first over heating. I do not know how old the thermostat is but my friends and father said it might be stuck closed??

 

Sounds like the thermo is stuck , like you mentioned. 121 c is hell hot for a rotary