Thermostat parts

[Joe_Mk5]

hi guys, driving back on the motorway car hit 110 degree warning lights were flashing! terrified, i pulled over and waited for the aa.. for 2 hours ill add.
the bottom pipe was still stone cold so he determined it was the thermostat getting stuck and not opening.
he has taken out the thermostat internals and the car runs fine but obviously only temp fix.
my question is do i need to buy just a thermostat to replace it or the thermostat housing?

I've seen a guide on how to change it from what tim gti posted on another thread! any help appreciated guys!

joe

[alexperkins]

just a thermostat - the housing will be fine

[Joe_Mk5]

cheers fella!
replaced the thermostat today at the grand total of £6.00
The problem still continues!

New thermostat put it. engine temp gets high, top radiator hose gets hot bottom stays cold.
however when the internals of the thermostat were taken out the car worked fine just took a while to get to temp.

Possible air pocket not letting the thermostat open?
im planning to take it apart tomoro and do the put it in boiling water to check its working trick

[alexperkins]

How high are we talking?

It may be a blocked rad if the pipe is still staying cold, or a faulty water pump.

You need to boil it in a pan of boiling water - they need constant heat to open fully.

[Joe_Mk5]

ive only let it get to 110 before i turn the engine off too let it cool down.
thanks for the advice mate on the boiling water.
Am i right in thinking it could possibly be air blocking the stat also?

[alexperkins]

Well its possible, but these have a self bleeding system

Remove the expansion tank top, and squeeze the top and bottom hoses gently. That should remove any air lock in the system

[Joe_Mk5]

just done all the squeezing and looks like there was no air.
let the car run up to 110 before turning it of, noticed that the fan wasnt working. bypassed the switch and the fan kicks in. my new theory is a broken fan switch.
ill replace it tomoro and let you know how it goes!

[dub6n2]

still if the fan was not working how come the lower radiator hose was cold? and if there was an air lock it usually releases its self when driving the car

[Joe_Mk5]

I've not dealt with a heating problem before, a friend of mine whos a mechanic said that the thermostat was opening and water was circulating.
We were testing it stationary but its really got me stumped.
im now thinking despite the fan working or not if driving along it should not need the fan to turn on, correct?

there appears to be no blockages in the system and the water pump is less than a year old. I am truly stumped.

Also would anyone know the fan switch name or part number, having difficulty trying to find it online.

[alexperkins]

whats your chassis number mate? PM if you wish. Ill get you the right part number

[Joe_Mk5]

PM'ed my friend

[Joe_Mk5]

thanks for the part number, just want to make 100% sure im ordering the correct part. its the switch that tells the front rad fan to turn on. im on GSF and there discription is calling it a thermo switch?

[alexperkins]

I'm 100% its correct. I checked it against your chassis number on the vw system
And yes that's what it is. Just give them the vw part number they will cross reference

[Joe_Mk5]

sweet mate, got the part fitted and its fixed the fans!
for future reference guys alex perkins is a top man

turns out the new thermostat fitted was also faulty so replaced that now its all cooling just right!
however theres now a leak from the join on the thermo housing and the other plastic bit that hold the thermostat that i forgot the name off!
sealant hasnt stopped the leak so looks like new thermo housing =[

does anyone know how complicated this is?

[alexperkins]

Its just a case of draining the system, removing the pipes, removing the old housing from the block then doing it all in reverse to refit