erratic temp guage

[userfriendly]

I think its normal bro kpag traffic maging half temp sya at kpag long drive syempre baba ng 1/4. or kung hindi yan ganyan dati well its not normal.. check the radiator cap and aux fan..
sir what car model and year?

Chevy Venture 2002 model. Installed original rad cap last week of April. Before this, temp did not go up and down. Defective kaya yung new rad cap? O defective yung old cap kaya di gumagalaw yung reading?

Check it pag 3/4 ang temp sisingaw yan somewhere.You will hear it.
Pag wala pa rin, its possible na sa cyl. gasket. Wag naman sana.
Do you have an overflow reserviour? May boiling ba doon?

Wag naman sana. Pero aside from the coolant loss, I dont see the usual sins of defective cyl head gasket. No white colored smoke, no oil discoloration, no oil in the coolant, no power loss.

The time it almost reached 3/4, I was not able to check the reserviour. If there is boiling, what does it indicate?

What are the symptoms of a clogged radiator? I don't use the manufacturers recommended Dexcool coolant. Read too many horror stories of it turning into gel and cloging the rad. May effect kaya ito?

Also, I can borrow a laser thermometer from work. If I measure the entering coolant temp and leaving coolant temp, how big a temp difference should I be looking at? May use ba to?