MK2 Golf GTI - Problems

[jackpe]

Hi,

Have been having problems with my MK2 GTI (80K miles, well looked after ).. the coolant light comes on when in traffic, once on the move it clears.

To test the fan I let the car idle today and once warmed up eventually the red blinking light came on.

I believe the fan (and the thermostat switch) is ok as it came on shortly after the light started blinking. The first time that happened it actually made the light stop bliking and then the fan stopped, the second time the fan ran for a while and then stopped...but the light carried on blinking.
I also disconnected the expansion tank switch and shorted out the terminals on the plug (in case it was a faulty sensor there) but the light carried on blinking.

I have been told it could be the impeller on the water pump that has corroded and is thus no longer pushing enough flow?

I think this has only started happening after the last service, could it be that they topped up with too much antifreeze and now the system is not cooling as well?

The temp gauge only reads close to half way, but I've been told to ignore it? I would like to work out if the car is actually overheating but without being able to trust the temp gauge I'm not too sure what to do.

[t4andgreys]

replace your thermostat, sounds like it could be faulty and sticking shut...
also as with most old cars worth while checking the radiator itself isnt partially blocked too

[Richie Howard]

is the rad hot? assuming switch is in the rad, if the fan is coming on, the thermostat isn't shut.

buy/borrow an infrared thermostat and take some readings at the pints around the engine, at the temp sensor in the block and how hot the rad is at the in/out points and the switch.

[LuS1fer]

My Mk III used to flash when the coolant level was low and had a slight leak somewhere that caused it to blink sporadically but topping it up always stopped it. It's not the easiest reservoir coolant level to be able to see either.

the other thing is that the coolant system seems prone to air locks. When I chaged the coolant, I had to give all the pipes a damn good squeeze to get the coolant all round the engine but you can usually tell from feeling the hoses if this is the problem.

[philh]

My thoughts are check coolant level mine used to show for low coolant also.

[shoestring7]

As an aside, it must be lovely to have a car where the warning light indicates a 'proper' fault, rather than some mysterious electrical problem/ECU having a bad day!

SS7

[jackpe]

philh said:

My thoughts are check coolant level mine used to show for low coolant also.

Checked already, including the sensor, both ok..

[jackpe]

shoestring7 said:

As an aside, it must be lovely to have a car where the warning light indicates a 'proper' fault, rather than some mysterious electrical problem/ECU having a bad day!

SS7

This is the point, I'm not actually sure the car is overheating... the fan only cuts in every now and again and then stops.. plus the temp gauge never goes past half way... though i have been told not to trust it..

[lowdrag]

Richie Howard said:

is the rad hot? assuming switch is in the rad, if the fan is coming on, the thermostat isn't shut.

buy/borrow an infrared thermostat and take some readings at the pints around the engine, at the temp sensor in the block and how hot the rad is at the in/out points and the switch.

Wrong way round surely? If the thermostat is open it is running too cold, not too hot. Anyway, modern thermostats usually fail closed, so she would run hot all the time. Old thermostats failed open, but ethose from an earlier date than this car.

[TISPKJ]

If it were me for the sake of a fiver or so I would change the thermostat, if your happy that the rad is fine then can't be a lot else can it ? Either way good rad and new thermostat at least you know it's potentially only an electrical gremlin and not something serious, albeit the electrical ones are the bu99er to fix !

[snood]

Pressure test on the cooling system? Could show where something might be awry.

[Richie Howard]

lowdrag said:

Wrong way round surely? If the thermostat is open it is running too cold, not too hot. Anyway, modern thermostats usually fail closed, so she would run hot all the time. Old thermostats failed open, but ethose from an earlier date than this car.

If the thermostat is shut, there would be no hot water going to the rad and the fan wouldn't come on (again, assuming the switch is in the rad).

[jackpe]

That't right.. the rad does get hot and fan goes on and off.. it seems like everyhting is working to an extent, but just not enough so my thoughts are either
1.there is a partial blockage in the system
2.or the impeller on the water pump has worn away and it is now not pushing enough water...
3.At the last service they topped up with too much antifreeze and now ratio is wrong and fluid is not cooling enough.

So i will flush the system this weekend and top uo with new fluid.. if this does not fix things then will need to check water pump..

[jith]

jackpe said:

That't right.. the rad does get hot and fan goes on and off.. it seems like everyhting is working to an extent, but just not enough so my thoughts are either
1.there is a partial blockage in the system
2.or the impeller on the water pump has worn away and it is now not pushing enough water...
3.At the last service they topped up with too much antifreeze and now ratio is wrong and fluid is not cooling enough.

So i will flush the system this weekend and top uo with new fluid.. if this does not fix things then will need to check water pump..

Hold on, you're giving yourself a lot of work, probably for nothing. There is no such thing as too much antifreeze; and it is not just antifreeze. It is a coolant mix designed to prevent internal corrosion and assist with cooling. Too much would definitely not cause overheating.

If the car is not using water, the cooling fan is operating and the temperature gauge reads normal, there is nothing wrong with the engine or your cooling system.

The warning light has a control diode at the back of the dash that brings the light on and also operates a warning buzzer. This will be activated if the car either overheats or loses oil pressure. They were a bloody nuisance in their day and I used to disconnect them because they would fire off for no reason. When this happened the buzzer would drive you mental!

A great many cars have now had them removed from the system, and you can do this by taking the dash out and isolating the light and buzzer, although it looks as if the buzzer has already been removed from your dash.

J

[jackpe]

jith said:

jackpe said:

That't right.. the rad does get hot and fan goes on and off.. it seems like everyhting is working to an extent, but just not enough so my thoughts are either
1.there is a partial blockage in the system
2.or the impeller on the water pump has worn away and it is now not pushing enough water...
3.At the last service they topped up with too much antifreeze and now ratio is wrong and fluid is not cooling enough.

So i will flush the system this weekend and top uo with new fluid.. if this does not fix things then will need to check water pump..

Hold on, you're giving yourself a lot of work, probably for nothing. There is no such thing as too much antifreeze; and it is not just antifreeze. It is a coolant mix designed to prevent internal corrosion and assist with cooling. Too much would definitely not cause overheating.

If the car is not using water, the cooling fan is operating and the temperature gauge reads normal, there is nothing wrong with the engine or your cooling system.

The warning light has a control diode at the back of the dash that brings the light on and also operates a warning buzzer. This will be activated if the car either overheats or loses oil pressure. They were a bloody nuisance in their day and I used to disconnect them because they would fire off for no reason. When this happened the buzzer would drive you mental!

A great many cars have now had them removed from the system, and you can do this by taking the dash out and isolating the light and buzzer, although it looks as if the buzzer has already been removed from your dash.

J

I have been given many different views on this (also on other forums). But the consensus seems to be that the temp gauge should not be trusted.. and that the warning light is activated by a sensor in the head (the temp gauge instead coming from the sensor in the rad?) and that therefore it should not be ignored, particularly if it seem to be working, coming on only when in traffic and going off again as car gets on the move and airflow helps cool the engine..

In any case flushing the rad won't do any harm and is not too much work so will try this... if light still on will get a Laser temperature gun to see how hot the head is getting..

[benjj]

It could well be a faulty sensor but if it was my car I wouldn't be taking chances. I'm a firm believer that if a car is kept well cooled and well lubricated then the chances of something catastrophic happening is limited.

I would almost certainly get the rad back-flushed (cheap as chips), new stat (again cheap) and make sure the system is well and properly bled. To do this you should jack up the corner of the expansion tank (or park on a kerb with it up) and give it a damned good rock so try and expel any trapped air.

[jackpe]

benjj said:

It could well be a faulty sensor but if it was my car I wouldn't be taking chances. I'm a firm believer that if a car is kept well cooled and well lubricated then the chances of something catastrophic happening is limited.

I would almost certainly get the rad back-flushed (cheap as chips), new stat (again cheap) and make sure the system is well and properly bled. To do this you should jack up the corner of the expansion tank (or park on a kerb with it up) and give it a damned good rock so try and expel any trapped air.

Will do...

Am also thinking of getting one of these so i can check the head temp, what do you guys think? should tell me if it is overheating or not..

http://www.ebay.co.uk/itm/Infrared-IR-Digital-LCD-...

[colc]

Might be a partially blocked radiator, or even a partially blocked heater matrix. Does the heater work properly?
I'd backflush the rad, sling some Daz [other washing powders are available]in there whilst your doing it, it does the same job as Radflush at about 20% of the price!

[jith]

jackpe said:

jith said:

jackpe said:

That't right.. the rad does get hot and fan goes on and off.. it seems like everyhting is working to an extent, but just not enough so my thoughts are either
1.there is a partial blockage in the system
2.or the impeller on the water pump has worn away and it is now not pushing enough water...
3.At the last service they topped up with too much antifreeze and now ratio is wrong and fluid is not cooling enough.

So i will flush the system this weekend and top uo with new fluid.. if this does not fix things then will need to check water pump..

Hold on, you're giving yourself a lot of work, probably for nothing. There is no such thing as too much antifreeze; and it is not just antifreeze. It is a coolant mix designed to prevent internal corrosion and assist with cooling. Too much would definitely not cause overheating.

If the car is not using water, the cooling fan is operating and the temperature gauge reads normal, there is nothing wrong with the engine or your cooling system.

The warning light has a control diode at the back of the dash that brings the light on and also operates a warning buzzer. This will be activated if the car either overheats or loses oil pressure. They were a bloody nuisance in their day and I used to disconnect them because they would fire off for no reason. When this happened the buzzer would drive you mental!

A great many cars have now had them removed from the system, and you can do this by taking the dash out and isolating the light and buzzer, although it looks as if the buzzer has already been removed from your dash.

J

I have been given many different views on this (also on other forums). But the consensus seems to be that the temp gauge should not be trusted.. and that the warning light is activated by a sensor in the head (the temp gauge instead coming from the sensor in the rad?) and that therefore it should not be ignored, particularly if it seem to be working, coming on only when in traffic and going off again as car gets on the move and airflow helps cool the engine..

In any case flushing the rad won't do any harm and is not too much work so will try this... if light still on will get a Laser temperature gun to see how hot the head is getting..

That's not accurate. The signal for the gauge comes from a transmitter in the head. There are at least 2 different systems according to engine code and injection system. 1 uses a separate sensor in the rear of the head, another uses the coolant temperature sensor in the water outlet on the side of the head. The principle behind this is that you will get early warning of overheating because the sensor is situated high in the engine so that even a small water loss will produce a high reading. The sensor in the rad is for the cooling fan.

I have had no problems with false readings from MK2 Golf temperature gauges in all the years I have worked on them. I have had numerous problems with warning lights and alarms. But go with the "experts" on the forums if you wish.

J

[Richie Howard]

I am with jith here. The only thing that sounds out of order is the warning light. The fan goes on in traffic and goes off when you are moving. The guage reads normal, you aren't losing any water and there's no steam pissing out.

A flush can't hurt, neither can a new thermostat, but it all sounds in order.

Check it with a thermometer (I can lend you mine if you are in London), but it sounds above board to me.