Fluctuating temperature - Head Gasket?

[dervpower]

So... about 2 months ago my car overheated due to looking the water because of a split pipe. This was replaced and re-filled with coolant, everything was fine.

Now and again the temerature gage will drop below 90 when it's warm, and then go up again. First time it did this I checked the coolant level to find it low, so topped it up again. This has now happened 3 times in about 2 months...

Told a few mates who said could be a head gasket?? I just assumed it was the system sorting it's self out after the new pipes...

Any info would be good.

 

[cupra.al]

could possible just be an airlock.

 

[rf860]

maybe another pipe is leaking, my old astra had loads of problems with the coolant system. I found that when one pipe burst a few other followed afterwards

 

[Copey]

think im having a similar problem, hoping it isnt a head gasket as thats an expensive job.

 

[GlanzaV]

Will, check the oil cap for "mayo" and have you noticed any sign of white smoke (steam) from the exhaust? I mean excessive amounts?

Usually my first response to the "Temp gauge dropping below 90 and back up again" scenario is always the thermostat... but if you think you've possibly cooked the head when you've overheated, and it's definately using coolant then maybe check for the other symptoms first?

 

[suj]

sounds like an airlock will

 

[Copey]

how wud u get rid of the airlock? mines sits just below min and then when i top it up it goes down abit more asif its eating collant then eventually it stop and i top it up to full.

 

[mazzerati]

take the coolant lid off and run the car up to temperature at idle. self bleeding system mate.

 

[suj]

some have bleed valves (not sure on the mk4)

if not, suggest draining the system, then refilling, then run engine running with cap off, so it lets the air out

yep or what mazz said

 

[Copey]

cheers guys, il give it a go.

 

[mazzerati]

Mk4 doesn't have bleed valves the tank is at the highest point of the system so it self bleeds