PLEASE HELP, HAVING A TOTAL NIGHTMARE mk2 gti 8v

[drivebycar]

Basically my mk2 gti 8v is overheating after a bit of a run, then once ive left it 15 mins, topped it up with water, if i drive it another 5 minutes its overheating again.

Now the problem is I cant figure out whats wrong with it. It was a really cold morning when it went so I first thought that maybe there was ice in the water pump which sheared the blades off. So after taking it apart I found the water pump was totally fine, and also it was missing a thermostat!!

So now im at the point where I may aswell check the head gasket but I was just asking to see if anyone had any ideas what it could be coz its like banging my head against a brick wall!!

Thanks

[Horney]

Fit a thermostat and replace the expansion bottle cap. See how you go with that before taking the head off.

Headgasket failure would usually show with mayo under the filler cap, any sign of that?

Nick

[drivebycar]

Was very little emulsification under the filler cap the first time it overheated, then went the second time, and no oil or anything in the coolant.

Dont think it is the head gasket but I spose it could always be a possibility, dont really fancy putting the engine back together, especially as im about 80% to changing the headgasket anyway! lol

[Horney]

Well in that case do the gasket anyway but deffo put a thermostat in and replace the expansion cap.

Nick

[drivebycar]

ok mate ill do that. Thanks for your help!! 

[herbster]

Hi, maybe the water been boiling off? When you checked the water pump did you check its adhesion to the shaft, they have a tendancy when over heated loose grip on the shaft, hold the pulley drive and the impeller in seperate hands and twist, if its solid its good. I have a temp problem on my k-jet, I don't run a thermostat in the system, have done a full rebuild of all wearables ie rings, seals, bearings, gaskets, still no change, but shes happy and never blows off, fan comes on at top of gauge scale ok and off again, fitted new heater matrix- no change, altered the timing - no change, in my experience as previously had a 87 scirroco with similar tendancies, as its happy I'll live with it. Do worry on a hot day if I get stuck in traffic though, open the windows and put blower on full heat for a while just to make sure it stays on the gauge!! 
Will do some temp readings with a gauge off the block soon to see what the actual temp is compared to the gauge on the dash, may even get a twin fan rad and wire one fan off the ignition then put a thermo back in the system, sorry if this has gone on but thought i'd share my findings, hope you sort it. 

[drivebycar]

should be doing headgasket n thermostat tonight, along with new expansion tank cap and prob water pump too. Will let you know how it goes!

[Conker]

Did you check the rad fan is working? Replacing the sensor and checking the wiring etc. is a cheap fix if not.