cooling problem

[j.l.forsen]

so recently my vehicles cooling system has been up and down at random times. sometimes itll almost get to boiling but then go down to normal and sometimes it wont do anything at very random times during a drive. so i thought it was a sticky thermostat, replaced that and still happens. any ideas? also i dont know if its related but my heater doesnt seem to be working either, i dont know if its just a coincidence and the heater core is screwed or what.

thanks

[Jordan Kruger]

Is your windshield getting wet on the inside?   do you have coolant under the dash running to the floor? 
that would point to heater core..

Make sure your rad fan/s are coming on correctly. You may have a dead fan relay  etc...

[Ryan Coft]

I hate to ask the obvious, but are you low on coolant per chance? Symptoms indicate so. If not go with previous suggestions above.

[John Hartman]

yep, check the level.

also, seeing as you recently replaced the tstat, make sure you burped out all the air.  If there is an air bubble, you will see these exact symptoms.

could also be a partially plugged rad, partially plugged heater core, obstructed line, failing water pump etc.  Or it could be a head gasket.  If the head gasket it still good, it won't be if you drive the car with the temp much above the normal middle position.

[Ivan Skare]

Change your coolant.

[John Hartman]

a good idea for maintenance, but even if he is running straight water, its not going to cause it to run cool sometimes and overheat other times.

Of course if he pressure flushes it and it removes some blockages, that will indeed help it maintain its, err cool 

[Brett Haviland]

sounds like a headgasket problem starting to rear its ugly head maybe....


You you dont find any obvious leaks... or after you top up the coolant and go for a hard drive and it pushes coolant out the overflow tank....  suspect the worst...  (headgasket)

[j.l.forsen]

head gasket was just done a year ago so im hoping its not that, the last drive i took nothing happened so ill keep my eye on it. and yes coolant level is up

[John Hartman]

hehe, I would say worst case would be a cracked head or block, but yea, bad if its the head gasket again.  Tho if it was done slightly incorrectly, its easily possible its gone again.