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Model specific boards => Golf mk2 => Topic started by: Benrevs on 26 March 2008, 19:22

Title: boiling over after new head...help plz!!
Post by: Benrevs on 26 March 2008, 19:22
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
Title: Re: boiling over after new head...help plz!!
Post by: mattneck(Beavis) on 26 March 2008, 19:35
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  :smiley:
Title: Re: boiling over after new head...help plz!!
Post by: Benrevs on 26 March 2008, 19:40
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.  :undecided: 
Title: Re: boiling over after new head...help plz!!
Post by: fused on 26 March 2008, 19:55
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!

Title: Re: boiling over after new head...help plz!!
Post by: Mew on 26 March 2008, 19:58
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.  :undecided: 

So are you now running it without the cap on the expansion tank?
Title: Re: boiling over after new head...help plz!!
Post by: Benrevs on 26 March 2008, 20:17
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!
Title: Re: boiling over after new head...help plz!!
Post by: Mew on 26 March 2008, 20:29
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  :wink:
Title: Re: boiling over after new head...help plz!!
Post by: odub on 26 March 2008, 22:05
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
Title: Re: boiling over after new head...help plz!!
Post by: Conker on 26 March 2008, 22:17
I'd check the themostat first.

Title: Re: boiling over after new head...help plz!!
Post by: DarnPB on 27 March 2008, 00:40
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. :wink:
Title: Re: boiling over after new head...help plz!!
Post by: Simeon on 27 March 2008, 00:45
Not particularly helpful perhaps, but a quick question re that /\ I thought the expansion tank cap was supposed to release the pressure up to a point, keeping the pressure in the system constant?
Title: Re: boiling over after new head...help plz!!
Post by: mattneck(Beavis) on 27 March 2008, 00:55
it does but it doesnt release all that air thats stuck in there.. tht needs to escape.

if run with the cap off the air comes through the system and out, keeping the bottle topped up during this period while eveything is being moved around helps to eliminate any air locks eventually
Title: Re: boiling over after new head...help plz!!
Post by: DarnPB on 27 March 2008, 01:32
The best thing to do before filling with coolant from empty is to remove one of the sensors, the black or the blue one. This allows the system to fill from the bottom, thus pushing the air out of the top. Also when filling, squeeze the hoses every now and again to 'pump' the water around. This will help release the air.
Title: Re: boiling over after new head...help plz!!
Post by: wopdat on 27 March 2008, 10:54
Silly question but have you checked the timing?!?!  :huh:

If the timing is out then the car will overheat and damage your headgasket!!!  :undecided:
Title: Re: boiling over after new head...help plz!!
Post by: Benrevs on 27 March 2008, 14:00
Cheers you lot it sorted itself eventually.. i just let it idle a bit more with the cap off and it sorted it.  Tis all good now, running like new  :grin:
Title: Re: boiling over after new head...help plz!!
Post by: Conker on 27 March 2008, 14:11
Nice one - A good cheap fix for you!!

A tip for refilling coolant... If you can find out how much coolant your system holds (I think my valver holds about 4 lires IIRC), if you measure how much you've refilled it with, you'll be able to tell if you've got a major air pocket if you can only squeeze in 3 litres for example.