Cooling system advice sought

[mrsandy]

Hi there

I'm desperately keen to get some advice on whether I can proceed with my planned Christmas journeys.

My 2003 VW Passat Estate (2L petrol, ~80000 miles) seems to have suffered with the cold weather; I have a strong suspicion that the coolant wasn't concentrated enough and that the extreme temperatures have caused some freezing.

The car has been fine until yesterday; it hasn't had any issues or known faults.

Yesterday, as I left work, the car instructed me to stop, as the coolant level was too low. I added about a litre of antifreeze plus about 250ml of water. I'm not sure if the antifreeze I added was of the same sort as was already in the system. The car was fine after this, and gave me no more warnings.

This morning, when I started the car I noticed the electric radiator fan came on (almost immediately). It was still on after about 10 minutes driving, but had stopped by the time I got to work about half-an-hour later. This was one of three symptoms that lead me to believe I have a problem with the cooling sytem:
1. The electric radiator fan comes on just after ingnition
2. The engine temperature gauge has ceased to function
3. The interior air blower isn't able to muster much heat, even with the control set to the highest temperature.

On my journey home, these symptoms remained and were joined by another: the emissions warning light is now on constantly. The coolant level had dropped a little since yesterday, I added about half a litre of top-up coolant.

I'm going to try to get my car to a garage tomorrow, but I'm not too hopeful that anyone will be able to take it.

So, can anyone advise me:
1. What is the chance of breaking down (I've got an 80 mile journey tomorrow and a 120 mile journey planned for Monday)
2. What risk I have of damaging my car
3. What I can do to keep it going

Many thanks.


Sandy

 

[Mursal]

Hi, in a perfect world it sounds as though the temperature sensor has failed.

But the no heat in the interior sounds more like low coolant level, or an air lock. Best to get it checked out if you can. Even a friend that could give a second opinion might be useful.

Don't keep driving if the coolant level is dropping excessively as you will do permanent damage to the engine. If you have to travel take coolant with you and top up at regular intervals before overheating starts.

If the emission warning light is on you cant drive as it could be a sign of coolant getting into the exhaust system or a misfire. This will destroy the catalytic converter.

 

[Peter.N.]

I would agree, a non working or inefficient heater is the first sign of water loss or poor circulation. Freezing would do it of course but if as a result it boiled it may have done some other damage. Check in the header tank that the water is circulating, may still be frozen, try adding neat antifreeze and bleeding the system.

 

[mrsandy]

Thanks to you both.

The coolant I can see in the tank in the engine compartment isn't frozen.

The rate of coolant loss seems slow; I'd be quite happy to keep topping it up over the next few days until the garage is open (I've already bought three bottles of top-up coolant). However, Mursal's comment about the cat converter causes me the greatest concern. I'll really have to try to get it into a garage.

My Haynes manual states (in bold) that differing coolants shouldn't be mixed. I'm worried that I might have done this - what's the risk?

Peter, when you say bleeding the system, do you mean completely emptying the radiator, or is there a way of release air pockets (like you would do with a domestic radiator)?

Thanks

Sandy

 

[Peter.N.]

Hi Sandy

I am not familier with your actual car but most have bleed screws at some high point/s to release any air trapped in the system, maybe on the radiator or the inlet hose to the heater. It should tell you in your Haynes manual.

Peter

 

[mrsandy]

Fantastic. Thanks again for your help.

 

[Belle427]

prime suspect for leaking would be the radiator if it has frozen to any extent

 

[jctilingservices]

and another possible cause of a water leak, if you have not had much anti freeze in, then possibly you have burst or slightly pushed out a water penny ( core plug )

But defo cold heaters are a sign of low coolant level, my personal opinion would be to get it sorted before going anywhere in the car

 

[bhm1712]

mixing the blue/green antifreeze with red/orange/yellow OAT antifreeze results in a nasty gloopy sludge which clogs up the coolant passages.This sludge normally finds its way to the heater matrix and blocks it, and the rest accumulates in the thermostat housing and at the top of the radiator. Its a pig to get rid of. I would check it as soon as possible to make sure you didnt mix them as it can lead to complete coolant system failure. It can block the matrix, damage the thermostat and damage the water pump impeller. All this can result in a blown head gasket, warped head or worse.

 

[ub7rm]

I can tell you a few common issues with VW's and cooling systems.

The sensors in the expansion tank that tells you its low on coolant are notoriously flaky in cold weather - easy fix you just buy a new tank. Only about £14 from the dealer.

Your coolant actually seems to be dropping so it might be telling the truth.

The plastic impeller on the water pump is weak and can shear off resulting in no circulation. Sometime a burst of hot water will make it to the temp sender in the engine block and the gauge will rise but fall again shortly afterwards. You must replace the water pump when you get the timing belt done - its a false economy not to. When was the pump last changed?

The temp sender in the engine block is again notorious for failing - gauge function will be intermittent and it will affect your fuel consumption / engine running. It will also affect your climate control system as it will think the water is cold and not control the heat properly. These side effects are a lot more pertinent to a petrol engine than a diesel.

Finally, if you have climate control are you sure that its in eco mode (air con off). When the air con is active the smaller fans in the engine run pretty much continuously and are not indicative of the coolant system. I.e. this might be the reason the fans run as soon as the ignition in on.

The temp sensor for the rad fans is separate to the temp sensor for the engine / gauge and it would be very strange that it would see enough temp as soon as you switch on the ignition to kick the fans on.

Some of the above may be relevant to you, some not hope it helps in some way.

I would suspect the pump, when they fail as described they often leak slightly. See if you can see any sign of coolant leaking by the bottom of the engine on the timing belt side.

Physically feel the radiator hoses to see if they are getting hot after a while.

You should be able to see the coolant return to the expansion tank?

Worst case, can you see any oil / mayonnaise in the coolant tank / oil filler cap. A little on the oil cap is normal this time of year if you only do short journeys.

HTH