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

[rubjonny]

when you bleed them what you should do is run it from cold with the header tank cap off, squeeze all the hoses you can reach constantly and every now & again rev the engine to 2k or so to really get the coolant flowing.  just doing it at idle wont always shift all the airlocks.
coolant wont always flow out of the thin top hose to tank constantly, but it should spray out whenever you rev the engine. if not the pump is faulty or the thin hose is blocked.
you keep at this until the level in the coolant tank starts to rise or boil, then you stop the engine and put the cap back on.  The fans dont normally cut in till the temp gets to around 3/4 on the gauge, and if its not a warm day it can take an age for the engine to heat up enough when its just sat idling.

sometimes even with all the above it takes a good motorway blast to shift some of the more stubborn airlocks

[Khare]

Yeah I was revving the engine and squeezing hoses when doing it, and I was sucking and blowing from the small pipe. Now you say it could be blocked though, I remember when I sucked it didn't take a lot of pressure create a vacuum, so it could wel be blocked. Might have to take it out and inspect it. I'm pretty sure the water pump is OK, I mean, if it wasn't it would have overheated before the new stat. Also, the fans used to kick in when the temp was at 90, it never went past 90 before.

[Khare]

Topped up 1/4 of a litre yesterday, car hadn't been used all day so I think I might have got rid of the airlock...We will see today when I use it.

[rubjonny]

worth taking that pipe off and checking it, if it is blocked it'll be a right sod to bleed the system. good excuse to give everything a good blast thru with a hosepipe, rad and matrix blast it thru both ways till the coolant comes out clear

[Khare]

Yeah I should have flushed the system while the stat was out. I'll do that soon as I think I'm going to change the pump soon too.

[PAZ GTi Concept]

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 

  Hi. Did you ever get the coolant system blead properly and temp / fan working as normal again? Or did it just come good after some driving?

[Khare]

well, not sure if the fan has started working again or not. I've done about 60 or 70 miles since the bleeding and it's not overheated since. Also kept an eye on the coolant and only needed to top up once, seems stable level now so I think there's no longer an airlock in there. I'll check if the fan is working today and report back.

[Khare]

It overheated in traffic. I'm thinking water pump/fan switch now although I "think" I heard the fan come on...Not sure on that though.

[JC]

really silly question, but you did fit the thermostat the right way round 

[Khare]

really silly question, but you did fit the thermostat the right way round 

Yeah I did. However I did doubt myself afterwards when it was overheating. I might need to stick a different stat in there and see if that could be the problem, although he fan not coming on could be part of the problem.