Khare's problem thread - Engine mount and screeching noise page 15. EUROPE TRIP!

[Khare]

Right. Today I changed the thermostat with a GSF replacement. Came out all good and easy and went in good and easy too.
Problem started when I refilled the coolant though. Danny had the same problem when he refilled the coolant after the conversion. Basically, the coolant doesn't go into the system very well, it struggles to be sucked in. As if there was a blocked pipe or coolant channel somewhere. The top rad pipe wasn't taking in any water and if squeezed it had no real effect on the water in the header tank. The small hose that diverts to the header tank also seemed to be empty of water. So I removed it and sucked from it to try and suck some water into the system but that didn't work.
So after lots of time waiting for the water to go down and having the engine running for the water pump to suck it though, I managed to keep it at a steady level. How I usually bleed a system is by filling up till no more goes in, then running the car till the fan comes on then topping up, problem this time though, the fan never came on. Water temp kept hitting 100 with no fan coming on (can I point out fan was working fine beforehand). The bottom rad hose got hot when temp hit normal levels so stat is working fine, I suspect....Anyway, after some waiting and more sucking and running the car I managed to get it to a steady level and drove off. Water temp stuck to 90 but oil temp was hovering around 94/96/98, normal in a valver I believe right? stopped off, waited 5 or so mins and I popped the header tank cap off to top up coolant, system was still under pressure so some coolant came out, so popped cap back on and drove off. Picked missus up and as I started to drive off water temp hit 110 and oil 102. So parked up and went back to hers. Waited about half hour then topped up half a litre, drove off and no overheating on the way back at all, oil tempo was still around 96 though.
So, my question is....would you suspect thermostat? Maybe not opening enough or not allowing enough hot water into the rad activating the fan switch? Or would you suspect fan switch suddenly had a fit and decided not to work any more? As I said, temp hit about 100 while bleeding and fan didn't come on. Bottom hose was hot, but top hose was hotter to the touch so I felt.
Ideas please 
Soz for long essay 

[Paul86S2]

Mine was a right git to fill and bleed. I found the only way was to run it up to normal temp then turn it off and leave it for a while (hour or so) then top it up and run it up to temp again and keep repeating until it stops needing more water and the fan works normally.
The fan temp switch is in the far corner of the rad and the air seems to accumulate there and stops the fan from working.

I also had the same problem of the system being pressurised but it was also full of air pockets.

Keep perservering.

Paul

[Khare]

Though as much as well Paul. I'll top up tomorrow and run up to temp again and see how that goes 

[Nino]

I know your pain matey, i did a full coolent change in my golf about a month ago took me bloody ages!!! i ended up taking off the bottom rad pip and one of the main pipes that go into the cabin, popped a hose thro and run it till it was clear and re-added my new coolent took me bloody ages to get it all thru

[Khare]

Thing is, when the engine was at operating temp and I touched the water in the header tank, it was stone cold in the header tank.....as if water isn't flowing though the system. I remember bleeding the old 8v that was real easy, water flowed through constantly. Could it possibly be a knackered water pump? I mean, before the bleeding, I had no over heating at all.

[christomk3gti]

bonnet up.... Rev run the car to normal operating temp....... Rev the engine while looking at the header tank. If u see flow in the tank then the water pump is fine. If you dont then its goosed.

[Khare]

bonnet up.... Rev run the car to normal operating temp....... Rev the engine while looking at the header tank. If u see flow in the tank then the water pump is fine. If you dont then its goosed.

That was the case with the 8v...But with the 16v I can't see anything. As I said, water isn't even flowing into the small pipe that diverts into the header tank. Thing is, hoses get warm and heat in the cabin comes out fine, so pump is definitely budging water...Maybe there's a blockage somewhere?

[Matty-MK3]

Water pump might be missing a few teeth. (If they're plastic like the Polos)

[Khare]

Water pump might be missing a few teeth. (If they're plastic like the Polos)

Yeah I did think that. Not sure if they are plastic or not though.

[Khare]

oh, if it helps to determine the problem, when the cap was off and the engine was on and had reached 90, the water stared being spat out very oddly. As if air was backfiring out of the header tank...2 or 3 "spits" every second or so. Turned engine off, back on again and it was fine....Did this a few times. Also, with the cap off, once it started boiling over it would just flood out a litre or so...Fan not kicking in at all as I said. Maybe water pump is completely shot?