g40 coolant problem

[vikash]

Firstly hello to all... I have just bought a g40... amazing...

I need a little help...

When I got home after 90 miles there was coolant that had come out of the header tank...

I checked when the engine was cold and the coolant level was too much. I drained the extra coolant until the level was max.

Let the car heat up and bled the air from the bleed screw. Once the car had cooled down the level was too low. I topped up the level to max. I let the car warm up and the level stayed the same. (I let the fan come on twice)

Went out in the car on a 80 mile trip and now the coolant is over the max mark. (should I wait until the morning to check again?)

The top and bottom rad hoses heat up. the fan works, but the temperature sensor never reaches 70 degrees.

The car has had a new radiator recently.

Could it be the thermostat or thermostat housing...


any help would be appreciated.

[PeteG40]

re overflow +max mark - check in morning and report back here.

re temp gauge, if the fan comes on it suggests the black temp sender might be giving a poor reading. this means you car worksok but the gauge registers wrong. try swapping it for a known good one.

[hayesey]

hi welcome to the forum!

bear in mind that water expands when it gets hotter so yes if you fill it to max when it's cold it'll go over max when it's hot.  I tend to fill it half way between min and max when it's cold.

As for the temp gauge, do you mean it ALWAYS stays under 70deg or just under 70 during normal driving?  I.E. even when you've left it on your driveway and the fan has come on, does it still read under 70 when that's happening?  If so then yeah replace the black temp sender on the front of the thermostat housing as Pete said.  If it's just when normal driving then it probably needs a new thermostat.

[vikash]

Checked the water level and it is now just a tiny amount above max.

I think the water gauge always stays under 70. I will check this when I go out again and report back.

While I have your attention is there a faq for general up keep of the g40..

I will be changing the oil every 5-6000 miles with genuine parts.

At how many miles should I be lubricating the supercharger?

The car is currently running 150bhp and it is rapid!!

thank you for the replies... much appreciated.

[vikash]

Okay a little update...

Went for another long drive. When idle the car once warmed up does not blow hot air. But with a minimum 1500 revs hot air starts to blow.

The temperature needle never goes over 70 when idling or driving.(but the engine cooling fan works)

I think this might be my water pump that is faulty.

As the car is my daily driver, i keep the revs at 1500 if I am stopped at the lights or in traffic.(so that hot air blows out and I assume this helps in moving the water?)

Will the car be okay to drive? or is it best to not drive and replace the water pump asap?

[Raw]

Welcome!

Where does the hot air blow from? I don't follow you.

It's quite a comon problem for Polos of this age to not read the correct temperature. Some people replace both sensors and the tehermostat and still have a problem, so I wouldn't worry about driving it. You can get realy paranoid driving cars of this age, the best thing is to do what you can in maintainance but not get nurotic about problems.

Replacing the water pump is a good idea along with the thermostat. The water pump tensions the cam belt so while it's off replace the cam belt.

[vikash]

The hot air is from the air vents (not the large ones they only blow cold air)

only reason I am is concerned is due to idle = cold air and when at least 1500 rpm = hot air. the air dial is on hot.

I do not want to damage the engine if I can avoid it. Prevention is better than cure as they say.

[hayesey]

that sounds very unusual!  Like you say it does seem to make sense that the water pump isn't doing it's job properly.  So in the absence of a better idea, I'd change that!

[lance]

yea mate sounds like your impeller has gone on your water pump prob a plastic one!!!

[vikash]

A little update for future reference if any one reads this message.

The problem was the thermostat. It was only partly opening when the car was up to temperature. This lead to the overflow of water out of the expansion tank.

Thank you all for the replies and help.

Vik