boiling over after new head...help plz!!

[Benrevs]

Have just put a new head on my 91 8v, its running fine but...
 
: Boils over within about 10mins  before the fan kicks in..
: Takes too long for the fan to come on..
: When it does the level drops an inch or so..
:If you squeeze all the hoses the level rises as it should..
  And its idling at just under 1500, not sure if this will settle after its ran in a little more.

If anyone has any suggestions i would be very grateful as its ready to go apart from this!!  Cheers

[mattneck(Beavis)]

new rad fan switch possibly?

mine buggered up and it wasnt cutting in at all.. and possibly the black sender, on the thermostat housign that control the water light and the gauge, maybe a message isnt gettign thru, when the fan kicks in though, the water elvel should drop - thats when the stat opens up 

[Benrevs]

Cool, we ran it with the cap on the expansion tank and it blew a hose.  right it drops so the stat is fine then. The water guage is not even a quarter when it boils and the oil temp is around 80.   im crossing my fingers and hoping we didnt do something stupid when we put the head on.   

[fused]

1500 idle is too high, follow rubjonnys guide to setting digifants up

http://www.golfgtiforum.co.uk/index.php?topic=33253.0

should be about 850-900rpm then set the CO and fiddle till they are both correct!

I'd flush the coolant then replace thermostat then maybe rad switch, they may be sluggish in doing the job!

[Mew]

Cool, we ran it with the cap on the expansion tank and it blew a hose.  right it drops so the stat is fine then. The water guage is not even a quarter when it boils and the oil temp is around 80.   im crossing my fingers and hoping we didnt do something stupid when we put the head on.   

So are you now running it without the cap on the expansion tank?

[Benrevs]

yes at the mo because it blew a hose when we had it on last time, its frustrating because it was fine before we pissed about with it so im guessing its something we have done..  errr!

[Mew]

yes at the mo because it blew a hose when we had it on last time, its frustrating because it was fine before we pissed about with it so im guessing its something we have done..  errr!

I'm gonna go with taking the cap off 

[odub]

personally i wouldn't run the car at all with the cap off as the cap holds pressure in the system and hence stop it boiling up. better off getting to the bottom of the problem. sounds like there could be an air lock, dodgy stat, etc. also worth getting it setup again after having the head off

[Conker]

I'd check the themostat first.

[DarnPB]

You have an air lock. The cooling system need to be bled. If there is too much air, this air will expand and because of the volume of the trapped air, there is no where for it to go except the weekest link. ie, expansion tank, knackered rad, bad hoses, etc.