For the last four journeys between Suffolk and Lincolnshire (200 odd
miles) the Polo has started playing up around the half way mark
(Cambridge or Peterborough services on the A14/A1M).

The last few times it's been bad enough that I've let it cool a bit before
opening the pressure cap and letting pressure escape before topping up
with more coolant. (hot engine cold coolant probably isn't too good- but
the drive is always after a long day at work and it's usually the last
thing I need).

Last time though the engine run really cool from the half way point after
my meddling around. Bear with me I'm certainly no mechanic.

I've since done an oil change, and flushed the radiator.

I seem to have narrowed something to do with the heating as a cause of
problems. After flushing the radiator I left the heater on full- but just
had the vent switched away from being directed into the car. I ended up
giving in and decided that a bit of cool air would be good on the way to
work. So adjusted the heater to cold and for the first time turned the
blower on.

Ever since then the card was juddering ( a sign that the coolant isn't
right ). So at the weekend opened the pressure cap- and the expansion tank
was full of water (after flushing the radiator I'd left it below minimum).

I know there is a coolant pipe to the heater matrix (that's where the
bleeder valve is), but I had guessed that coolant would flow around all
the time. But now I'm guessing that some coolant must have been trapped in
the heater matrix somehow (this I don't fully understand) and when putting
the blower on it was released into the coolant around the engine.. (which
is how it seems to create 'extra' coolant).

I'm trying to understand when the thermostat opens to let coolant rush
around the radiator. The needle looks something like this (ASCII art)

|-------------------------------------------|
| \-----\\--------------------//----/ |
| \ \\ //---/ |
| (a) \ (b) \\ (led) //--/ |
|-------------------------------------------|

I think my best guess is that the thermostat is closed until the needle
enters (b).. then it starts flowing around the engine. The normal
tempreature seems to be a just before the led (which is central in the
gauage). I always end up pulling over if it touches the dashed region on
the right. The electric fan kicks in if the needle passes the (led)- at
least I know it does when stationary but not convinced it kicks in in
motion at 60mph.

After opening the bleeding valve at the weekend and flushing coolant out
the bleeder valve- then topping up with fresh coolant it seems to be
behaving itself. (Too a run from Ipswich to Rendlesham forrest and back
home and the temp stayed the left side of the led until I got back driving
through the village.

The choke is knackared (only works on the coolant, the electric part of
it is broke)- and in combination with a carb that a few blokes have said
isn't too great means that at times when sat at a junction it just guzzles
through fuel. (The other problem is the emissions were bad for the last
MOT, but it scraped through).

The MOT is due in October- I'd rather keep the car going till October (and
if possible an extra year), then I can save really hard to buy a
replacement- though been a polo the body work is still in a good way.

If anyones made is this far, thanks, and anything that is easy enough
to check/replace (no more than 3 spanners in the haynes manual) I'd be
greatful for the pointers.

(Or anyone who owns a garage in Ipswich/Woodbridge that can fix it without
charging the earth, I'm ultimately a lazy person).

--
Regards,
Adam

PGP: http://pgp.mit.edu:11371/pks/lookup?...e.net&op=index

Perhaps if you stopped trying to understand it (it's a car for christ's sake
!) it wouldn't overheat anymore .....


"Adam" wrote in message
news
For the last four journeys between Suffolk and Lincolnshire (200 odd
miles) the Polo has started playing up around the half way mark
(Cambridge or Peterborough services on the A14/A1M).

The last few times it's been bad enough that I've let it cool a bit before
opening the pressure cap and letting pressure escape before topping up
with more coolant. (hot engine cold coolant probably isn't too good- but
the drive is always after a long day at work and it's usually the last
thing I need).

Last time though the engine run really cool from the half way point after
my meddling around. Bear with me I'm certainly no mechanic.

I've since done an oil change, and flushed the radiator.

I seem to have narrowed something to do with the heating as a cause of
problems. After flushing the radiator I left the heater on full- but just
had the vent switched away from being directed into the car. I ended up
giving in and decided that a bit of cool air would be good on the way to
work. So adjusted the heater to cold and for the first time turned the
blower on.

Ever since then the card was juddering ( a sign that the coolant isn't
right ). So at the weekend opened the pressure cap- and the expansion tank
was full of water (after flushing the radiator I'd left it below minimum).

I know there is a coolant pipe to the heater matrix (that's where the
bleeder valve is), but I had guessed that coolant would flow around all
the time. But now I'm guessing that some coolant must have been trapped in
the heater matrix somehow (this I don't fully understand) and when putting
the blower on it was released into the coolant around the engine.. (which
is how it seems to create 'extra' coolant).

I'm trying to understand when the thermostat opens to let coolant rush
around the radiator. The needle looks something like this (ASCII art)

|-------------------------------------------|
| \-----\\--------------------//----/ |
| \ \\ //---/ |
| (a) \ (b) \\ (led) //--/ |
|-------------------------------------------|

I think my best guess is that the thermostat is closed until the needle
enters (b).. then it starts flowing around the engine. The normal
tempreature seems to be a just before the led (which is central in the
gauage). I always end up pulling over if it touches the dashed region on
the right. The electric fan kicks in if the needle passes the (led)- at
least I know it does when stationary but not convinced it kicks in in
motion at 60mph.

After opening the bleeding valve at the weekend and flushing coolant out
the bleeder valve- then topping up with fresh coolant it seems to be
behaving itself. (Too a run from Ipswich to Rendlesham forrest and back
home and the temp stayed the left side of the led until I got back driving
through the village.

The choke is knackared (only works on the coolant, the electric part of
it is broke)- and in combination with a carb that a few blokes have said
isn't too great means that at times when sat at a junction it just guzzles
through fuel. (The other problem is the emissions were bad for the last
MOT, but it scraped through).

The MOT is due in October- I'd rather keep the car going till October (and
if possible an extra year), then I can save really hard to buy a
replacement- though been a polo the body work is still in a good way.

If anyones made is this far, thanks, and anything that is easy enough
to check/replace (no more than 3 spanners in the haynes manual) I'd be
greatful for the pointers.

(Or anyone who owns a garage in Ipswich/Woodbridge that can fix it without
charging the earth, I'm ultimately a lazy person).

--
Regards,
Adam

PGP: http://pgp.mit.edu:11371/pks/lookup?...e.net&op=index

In article pan.2004.08.02.23.06.48.263630
@use.pgp.signature.for.clues, s
says...


snip cooling problems

Firstly, each time you open the expansion tank when the car is warm,
you increase the chance of putting air into the system, especially if
it starts to boil.

I'd guess that you almost certainly have air locks in the system,
however the fan coming on when stationary means that the thermostat is
working and routing the coolant through the radiator. The fan doesn't
need to be on when the car is in motion.
When the car is warm, feel the top and bottom hoses and across the
radiator, if there are any cool patches then you may need to re-flush
and re-fill the system. I spent a good couple of hours a few weeks
back trying to get the air out of my Golfs cooling system, when you
think you've done it, leave the car for a few days if possible and then
check the coolant level when cold. If you still have air in the system
then the coolant level may drop.

It's all "may's" and "could be's" though i'm afraid...


--
Trooper
(remove the obvious)
GamerTag: TrooperNeil
City of Heroes: Ice Trooper, Old Red, Wonderous Kevin on Victory

On Tue, 03 Aug 2004 09:50:23 +0100, Trooper wrote:

snip cooling problems

Firstly, each time you open the expansion tank when the car is warm, you
increase the chance of putting air into the system, especially if it
starts to boil.

I'd guess that you almost certainly have air locks in the system, however
the fan coming on when stationary means that the thermostat is working and
routing the coolant through the radiator. The fan doesn't need to be on
when the car is in motion. When the car is warm, feel the top and bottom
hoses and across the radiator, if there are any cool patches then you may
need to re-flush and re-fill the system. I spent a good couple of hours a
few weeks back trying to get the air out of my Golfs cooling system, when
you think you've done it, leave the car for a few days if possible and
then check the coolant level when cold. If you still have air in the
system then the coolant level may drop.

It's all "may's" and "could be's" though i'm afraid...

I'm trying not to open the expansion tank at all- since I figure that will
give chance for air to get trapped in. So when the engine gets *too* hot
it boils the coolant giving chance for an air lock- forcing the coolant up
in the expansion tank (my creating 'extra' coolant situation).

I hadn't tied in that the fan operating meant the coolant was getting
routed through the radiator- so some part of it works. But I guess it must
be other wise the thermostat wouldn't trigger the fan.

Just had a feel around the pipes and they all seemed equally warm, except
the pipe from the engine to expansion tank (but right/wrongly I'd expect
that)

The coolant is at the right sort of level now, and the engine hasn't got
too warm to and from work today- so I'm going to leave well alone till
Friday and see if I end up stopping at Cambridge / Peterborough.

Thanks for your response it's triggered a few brain cells in my
Engineer-like mind (it's just a shame I never showed interest in how cars
worked before now)

--
Regards,
Adam Allen.

PGP: http://pgp.mit.edu:11371/pks/lookup?...e.net&op=index

In article pan.2004.08.03.19.30.07.137632
@use.pgp.signature.for.clues, s
says...
On Tue, 03 Aug 2004 09:50:23 +0100, Trooper wrote:

snip cooling problems

Firstly, each time you open the expansion tank when the car is warm, you
increase the chance of putting air into the system, especially if it
starts to boil.

I'd guess that you almost certainly have air locks in the system, however
the fan coming on when stationary means that the thermostat is working and
routing the coolant through the radiator. The fan doesn't need to be on
when the car is in motion. When the car is warm, feel the top and bottom
hoses and across the radiator, if there are any cool patches then you may
need to re-flush and re-fill the system. I spent a good couple of hours a
few weeks back trying to get the air out of my Golfs cooling system, when
you think you've done it, leave the car for a few days if possible and
then check the coolant level when cold. If you still have air in the
system then the coolant level may drop.

It's all "may's" and "could be's" though i'm afraid...

I'm trying not to open the expansion tank at all- since I figure that will
give chance for air to get trapped in. So when the engine gets *too* hot
it boils the coolant giving chance for an air lock- forcing the coolant up
in the expansion tank (my creating 'extra' coolant situation).

I hadn't tied in that the fan operating meant the coolant was getting
routed through the radiator- so some part of it works. But I guess it must
be other wise the thermostat wouldn't trigger the fan.

Just had a feel around the pipes and they all seemed equally warm, except
the pipe from the engine to expansion tank (but right/wrongly I'd expect
that)


The small diameter overflow pipe that runs to corner of the expansion
tank? (I'm only used to Golf GTis, so don't know if it is the same on
yours)
That has been known to get blocked up, so when the coolant heats up,
that blocked pipe can mean that it has no where to go...
If you still have problems, take that pipe off and flush it.

As an aside, the thermostat doesn't trigger the fan as such. The
thermostat opens when the coolant gets to a certain temperature, this
then routes the coolant through the radiator rather than just
circulating round the engine. There is a temperature regulated switch
on the radiator that triggers the fan once it heats up. These are
notoriously unreliable and if you have an air lock in the same location
as the switch, it will never turn on the fan.


--
Trooper
(remove the obvious)
GamerTag: TrooperNeil
City of Heroes: Ice Trooper, Old Red, Wonderous Kevin on Victory

On Wed, 04 Aug 2004 09:21:29 +0100, Trooper wrote:

The small diameter overflow pipe that runs to corner of the expansion
tank? (I'm only used to Golf GTis, so don't know if it is the same on
yours)
That has been known to get blocked up, so when the coolant heats up, that
blocked pipe can mean that it has no where to go... If you still have
problems, take that pipe off and flush it.

As an aside, the thermostat doesn't trigger the fan as such. The
thermostat opens when the coolant gets to a certain temperature, this then
routes the coolant through the radiator rather than just circulating round
the engine. There is a temperature regulated switch on the radiator that
triggers the fan once it heats up. These are notoriously unreliable and
if you have an air lock in the same location as the switch, it will never
turn on the fan.

I managed to get from Suffolk to Lincolnshire with-out any overheating
(I really expected to be going on the back of a breakdown truck).

I've spoke with a garage up north (where things will hopefully be a bit
cheaper)- and from my description they reckon the timing belt is ready for
replacing.

It was very rough running over the last few days, and "popping" out of the
exhaust. Once at 60/70 mph it flew along, but struggled to get from 0-40
and then struggled a bit more from 40-60. Hopefully it's something that
can be sorted for less than £200.


--
Regards,
Adam Allen.

PGP: http://pgp.mit.edu:11371/pks/lookup?...e.net&op=index