The coolant will boil anyway if you leave cap off as water boils at 100 degrees at atmospheric pressure. The boiling point rises with pressure, anyways, what is it doing? Put on cap, does it boil then? Does it boil at idle just when standing or is it ok when driving(over 30mph) Is the fan coming on when parked in traffic? Is the heater still blowing hot air inside?
To me, the car seems fine, just dont take off the cap.
If it boils with the cap on when standing there can be a few things wrong,
O ring seal gone in cap.
Cap faulty.
Leak somewhere.
Headgasket gone.(your last possible problem)
Fan not coming on.
Rad blocked.
Waterpump shot.
Thermostat stuck closed(rare)

Bring it for a good run and see if its ok, also face the heater vent at your hand on the steering wheel, if it goes cool on the move at any point you have a problem.(see above)
First check, fit cap, leave ticking over and wait to see if fan cycles.

Brian.

 

thanks brian..
ruled out waterpump as took off hose and can see water is being pumped around.
the fan is not coming on but have it on a switch and have it on.
if i leave cap on..even after a few min the pressure on it if go to loosen it is extreme!

 

must take it for proper drive 2moro but think heaters gone alright :/

 

QUOTE (GtiPower @ Jun 11 2010, 12:58 AM) <{POST_SNAPBACK}>thanks brian..
ruled out waterpump as took off hose and can see water is being pumped around.
the fan is not coming on but have it on a switch and have it on.
if i leave cap on..even after a few min the pressure on it if go to loosen it is extreme!
Is the rad getting hot when stat opens? Why is there a switch on the fan? Pressure under cap is normal, itll vent if it needs to.
Top it up and bring it for a run, keep an eye on interior heat, if it goes cold after a good run or during pull in and see has bottle vented

 

no dont think rad is getting hot..put in a another rad this evening and fan still not coming on so just threw a quick switch on it before took it for quick spin. i doubt sensor heat switch gone in both rads so what could be my problem there...?

 

Have you gotten the car scanned with VAGCOM?

I bet one of the temp sensors is gone and thats why your fans aint coming on. Either that or the fan controller is fubar'd which is a common problem.

Doesnt sound like you have a head gasket failure though at all.

 

no never got it scanned. ya rad works when cross it..even when changer rad still didnt come on itself tho so isnt the fan switch sensor..what other one could it be?? seems to be some smoke coming from one of the injectors now too... :/

 

Id get someone with VAGCOM to scan your car for you and see if you have any temp sensor faults.

They can force the fans on/off as well to see if the car has control of them.

I dont know what you mean by "changer rad"?

There are 3 sensors altogether:

The green one in the coolant flange at the right hand side of your engine (the most common one to fail and cause issues)
There is one in the lower pipe coming from the radiator
And there is one in the thermostat housing itself which is under your alternator.

 

Be careful Dave, this is a Mk3 Golf so pretty old school compared to what you are used to

@ GTIpower which engine is in this car?

 

Doh, forgot about that.

Not every VAG is a 1.8T Dave!

 

QUOTE (Geo @ Jun 15 2010, 09:10 AM) <{POST_SNAPBACK}>Be careful Dave, this is a Mk3 Golf so pretty old school compared to what you are used to

@ GTIpower which engine is in this car?
The car must have spontaneously combusted...

 

did u get this problem fixed bud...could be your waterpump belt that could be worn also....is your battery charging because belt is connected to the altenator..

 

got her checked over and was told head gasket gone alright

she's a straight 1.9 diesel

 

not a huge job on these really. few hours will get it done, what made it go?

 

fan stopped working and she overheated a small bit. would i have to get her pressure tested dya think? thats where the cost comes in :/

 

where you from??
heads are cheaper than pressure testing them, if you think its gone just replace it. usually they just warp and need a skim though.
i have heads here if you need one.

 

just get a new gasket and put on another head should do it so? cork..probably get one closer to home but how much looking out of interest maybe??

 

you should get one closer so.
50quid.

 

ya should do..thanks anyway

anyone in cork/munster area have one for me??