RED thermostat light UPDATE + PICTURES

[marke]

Hi guys. I am an mechanical noob so go easy on me.

After a long journey back from motorway as I pulled down my road, the thermostat light pinged and flashed red about 10 times.
this happened when I put the key in the ignition the next day as well. I was not to sure what it was but as I was driving to my dads
last night the gauge kept going up, and it went to the top so i decided to pull over, just as i did there was lots of what I thought
was smoke coming out the back but upon inspection it turned out to be steam. The left hand side water container overflow thing
had popped its blue lid off, and everything was hot including the water. After I let it cool down I decided to make it back home in
short trips, stopping to let it cool down as I did. Eventually I made it back and the battery was virtually dead from all the restarts.

What could this BE ? I looked in to Haynes manual and I thought it could be the thermostat switch is not working/kicking in when
it gets to a certain temp, but then how would it know that before I even start the engine. There is plenty of water and coolant.

I await some VW pro advice, many thanks

Mark

[tonytech]

First off.. Please let us know what engine you have? Petrol or diesel?
The red light SHOULD flash when you start the engine. it does this so you can see it is working.

The first thing to do is to have a read of the wiki above (lots of info there)
It may just be that the pressure cap has failed and needs replacing, however you will need to bleed the cooling system before venturing out again.

T

[marke]

petrol engine 1900ish which was an injection but a carb was put on because of the LPG conversion
http://www.westfaliat3.info/html/westfa ... ion_j.html

by the way, why do i need to bleed the cooling system. ( out of curiosity )

[kevtherev]

The red flash is telling you the water level in the header is too low
So there must be a reason why it dropped and you need to investigate that.
I would bleed the system after topping it up

[marke]

kevtherev the headtank is full and so it was the other night when the overflows blue lid popped off.
someone said i could have left it unscrewed, but the huge cloud of steam would not have come out
in one go unless it was bust out. Im in the process of trying to get the thermostat out to test it
but for a newbie its a bit of a mission because its one of those old underneath ones. Im not sure
as the haynes manual is a bit crap for the pictures, but how does the solid pipe coming in from the
right get disconnected? im sure that the other 2 pipes come off via the screw clips. Also i cannot
find where i drain the coolant fluid out underneath, it all look black and the book only shows a small
unhelpfull and drawn picture. i will scour the web for some more info

[kevtherev]

OK
If you were travelling along and the light started flashing it would suggest the header tank was emptying itself via the cap coming off, and filling with combustion gas.
One reason I could think of would be the engine combustion gasses pressurising the cooling system to such a pressure to cause such a lot of pipes and caps coming off, would be because of a gasket failure.
I may be wrong it's just my thoughts based on what you have said

What was the gauge showing when the red light flashed just off the motorway?

If it was normal then what I said could have happened
If it was way up, you cooling system boiled up because the stat didn't open perhaps, or a pipe blockage maybe

[marke]

Ok guys a bit of an update. My freind managed to get the thermostat housing off from underneath (which was a REAL pita)
we just disconnected the hose that came off of the thermostat housing as shown in yellow, but hardly any coolant came out

I then tested the stat in a jug with hot water in the microwave for like 40 seconds and the thermostat opened up.

So my problem is thus; When I put the key in and turn on electrics the templight flashes like 10 times and then when
driving the engine starts to go right up to the top of the gauge and over heats. the thermostat opens when it gets hot
and the coolant level is at MAX.... what happened when it got too hot for a while was the blue cap popped off but i think
that might be because it was not on properly, either way when it was put back on correctly it still over heated.

any ideas guys

mark

[Plasticman]

Yep.. You were asked earlier if you have or had bled the cooling system, have you?
also was the microwave happy with a metal stat in it?
mike

[kevtherev]

ye gods man.... find out how microwaves work and you'll see it's not a reliable test of a thermostat.

put it in a pan of water with a thermometer, heat it... and take note of the temp when it first opens (should be 87 deg C)

[marke]

i will bleed the system in the morning.
Metal in a microwave does not cause trouble if it is submerged under water as the radiation is designed to hit the water molecules
which act as a buffer in a way. I would not leave it too long though. The temperature was not boiling but it was hot and the thermostat
opened, so if water boils at 100 and it was not boiling and i could put my finger in just about and the thermostat opened i would say
that was near enough ? check out this video as well.
http://www.youtube.com/watch?v=eo1aWdHNjs8
thanks for your advice chaps and ill let you know how the bleeding goes. and also my pal and I will check the closed loop pipes as well
if its not getting round past the stat and the stat is working... perhaps a blockage is right like someone said

ill also test stat again with pan....

TA

mark

[T25Convert]

Hi,

If i understand correctly you have a:

1) Header tank full of water

2) Theromstat (mildly radioactive), but apparently fully functioning

3) A red light that does the self diagnostic (flashes ten times or so at start up), which only means the light is working

4) A van that just gets hotter and hotter and hotter.

Assuming you have bled it properly does the radiator fan kick in? You'll know, as when the gauge goes to the right of centre you should be able to hear it running at the front of the vamn. You seem to have discounted this in your initial post, but not sure why.

When on the m'way you wouln't have overheated as you have a steady flow of air forced in, but when you stop the whole lot heats up.

Cheers,

Alex

[Plasticman]

Alex, I think you still would overheat for the rad fan to cut in it needs hot water and if not bled then nowt much to set it off? agreed though that if full of water and bled its usualy kept cool enough with airflow when driving,
Could be lots of things, even hoses wrong way round to the rad etc etc
Mike

[kevtherev]

As a side note...
the micro waves would have melted the wax in the thermostat way before the water got anywhere near hot enough
...and as we all know that's how thermostats work..
the hot water should melt the wax allowing the valve to open... not radiation

unless it's a bi metal spring type

[marke]

ok guys quick update, and i will just add that i am really grateful for the people on this post who spent time to reply for me, thanks alot
as i said originally that i am a total engine noob and with each problem im faced with im learning a little bit more. as we were trying to bleed
the engine good old jedthespread drove past in his syncro and stopped and helped out. IT WAS LOW ON WATER and i was checking the overflow
instead of the main header. the main blue cap was loose so as it got hot over time more was lost in steam until eventually it got really hot and
popped the cap off. I replaced some water (coolant to come from brickwerks) and ran the engine and it stayed cool, hooray. so there you have
it, it was just low on water, no need to check the stat which was in a b1tch place to get off, although i know where it is now! the stat by the way
had a spring round it and so i think that it was not wax filled ? anyway when the coolant arrives i will probably have questions about bleeding it
because we were not getting any noise out of it when we tried

thanks alot 8090 guys and gals!

mark