toledo fan problem

[simon4]

My car has started overheating and boiling out coolant when it is driven quite hard. I have noticed that the only time the fans come on is when the car overheats (110*c +) and when the air con is on. I know the fans should come on when the temperature hits 93 but my fans dont come on.....any one got any ideas as to what the problem maybe?

Thanks
Simon

 

[Muttley]

Fan control module.
Radiator thermoswitch.
slow speed resistors in the fans themselves.

Any fault codes stored?

I hope you haven't damaged the engine already. Not a good idea to drive it to the point of overheating.

 

[simon4]

i had the head gasket fixed about a week or two ago and then this! it was obviously the cause in the first place.

when i put the air con on it makes the slow fans come on. so i dont think its the resistors.

nope no fault codes sorted.

il try the radiator thermoswitch as its the cheapest option!

 

[dvance]

It might be worthwhile to check if your fans work on the high setting as well -- I'll post up a link if your thermoswitch change does not work or if you want to try it anyway.

But as suggested -- if fans work, then try thermoswitch, if that works -- then fan control module (under battery), if it's not that maybe water pump?

I would think it's the thermoswitch though as your fans seem to work (and theoretically the high setting should not stop working unless your control module is bust).

 

[simon4]

It might be worthwhile to check if your fans work on the high setting as well -- I'll post up a link if your thermoswitch change does not work or if you want to try it anyway.

But as suggested -- if fans work, then try thermoswitch, if that works -- then fan control module (under battery), if it's not that maybe water pump?

I would think it's the thermoswitch though as your fans seem to work (and theoretically the high setting should not stop working unless your control module is bust).

ive changed the thermostat, waterpump and head gasket. When we changed the gasket it sorted the overheating for a bit but then it came back, this is when we noticed that the fans where only coming on when my car was boiling.


Thanks for the help so far lads!

 

[jaydean]

toledo overheating

i have been having a similar problem with my seat toledo it over heated the yesterday and it baffled me.. i noticed my fan weren't kicking in at all so i unplugged it and put a charge to it and tested the fan first of all the fan was working fine so i replaced the thermo switch and the fan still not kicking in, i dont think it is the pump.. could it be in air lock or control modual??

 

[simon4]

i have been having a similar problem with my seat toledo it over heated the yesterday and it baffled me.. i noticed my fan weren't kicking in at all so i unplugged it and put a charge to it and tested the fan first of all the fan was working fine so i replaced the thermo switch and the fan still not kicking in, i dont think it is the pump.. could it be in air lock or control modual??

as far i know these cars should self bleed themselves?. could be the control module, im heading on holidays now but when i get back im going to fit a new thermoswitch and if that does work im going to fit a new control module.

 

[Ictoanuk]

ive changed the thermostat, waterpump and head gasket. When we changed the gasket it sorted the overheating for a bit but then it came back, this is when we noticed that the fans where only coming on when my car was boiling.


Thanks for the help so far lads!

I wonder if you may have two problems here, not just the fans failing to kick in.

Usually, I would only expect the fan to kick in when stationary. The flow of air through the rad as the car moves and a correctly operating thermostat should generally be sufficient to keep the engine cool. I wouldn't expect the temp to rise above 90 in normal (or even hard) driving. If the temp is rising above 90 then I would suspect the coolant is not circulating correctly, which would point to either the thermostat - does the rad get hot or does it stay cool? If cool, then I would suspect the thermostat (though you have changed that) or if the rad gets warm, the water pump as there would still be some movement of coolant due to the difference in temp at different points (but you've changed that as well). Check the pipe from thermostat housing to rad.

However, you also mentioned that it is 'boiling out' coolant. This indicates the system is pressurising. That could be caused by a faulty thermostat (see above) or a big air lock - top up the system and run the engine with the expansion tank cap off until it is warm and the thermostat opens and squeeze all the water pipes you can find to force any air out of the system. (**CAUTION-watch out in case the fan does kick in and also don't scald your self)

Another possibilty is that the head is warped or cracked or there is a problem with the new head gasket. Once you are sure you have got rid of any airlocks check for bubbles coming up into the expansion tank when the engine is running. Have you noticed any oil in the water or water in the oil? (usually shows up as a mayonnaise type sludge on the oil filler cap or around the dipstick).

There is quite a bit there to check, but worth doing before spending any more cash.

Another thought, if the water in the rad isn't getting hot then the fans won't kick in, which would mean a circulation problem (back to thermostat or huge airlock).

When I get problems like this it's always worth going back to the basics.

Apologies if it sounds like I'm trying to teach my granny how to suck eggs.

Good luck and let us know how you get on.

 

[Ictoanuk]

Any update Simon04? Did you get it fixed?

Tim

 

[simon4]

the head gasket was blown, so i had it skimmed and repaired. now the car does not over heat but the fans still fail to come on, ive tried a new thermoswitch, new control module and still no luck, the slow speed fans come on when i turn on the aircon.... i really dont know what to try next

 

[dvance]

Okay, I think you're at a point where you need to run some tests rather than keep changing parts.

This is a quote from this page: UK MKVs Forum Thread on Fans

First the fans themselves.
Disconnect the fan connector and measure, with a multimeter, the resistance between the red/white wire and the brown wire, it should be a value less than 10ohms, a much higher value indicates a burnt out internal resistor. Next measure the resistance between the red/black wire and the brown wire it should also be a value less than 10 ohms, a much higher value indicates a burnt out fan.

Next the fan controller, fuses etc.

The test detailed is taken from the VW repair manual for the V5.
Caution keep hands etc away from the fans during this test as they are expected to run:

Reconnect both fan connectors, if still disconnected, and disconnect the 3 pin connector from the radiator fan thermo switch.
Bridge contact 1 and contact 2 with a short piece of wire, the fans should run at low speed.
Switch on ignition, bridge contact 2 and contact 3 with a short piece of wire, the fans should run at high speed.
Switch off ignition, reconnect thermo switch connector.

To identify the connector pin numbers, hold the connector facing you with connector latching mechanism at 2 o'clock, pin1 is then at 12 o'clock, pin 2 at 4 o'clock and pin 3 at 8 o'clock.

For anyone who wishes to try to test the thermo switch, low speed is switched on between 92 and 97 degC and the high speed switches between 99 and 105 degC.

This should tell you if your fans are alright, from there on you can follow the chain and see where the problem lies. The way I see it if your rad warms up, and you've changed the thermoswitch and controllers for ones that definitely work, it could only be the fans themselves (although if they work on slow speed they should work on high speed) or a wire is broken somewhere.

EDIT: PLEASE READ! I don't think your high speed would ever come on unless -- you're stationary, and it's really hot. If I were you and performed the above tests and found out that my fans work alright, then I won't worry as long as that temp gauge stays at 90C

 

[Ictoanuk]

Good to see you eventually got the cooling sorted, must admit it was starting to look like it might be the head.

Regarding the fan problem, tend to agree with Dvance that the high speed fan should very rarely come on. When working correctly the cooling system is pretty efficient and the temp guage never wavers. I would bet that virtually all owners would never be aware there was a problem unless the temp went over 90, and in normal running it should never do that.

Tim

 

[romeo]

Hi i have a very similar problem where my car oil temperature doesnt rise when im driving and moving but when i am staionary for few mins t reaches 90 but as soon as i start moving it starts to drop and hits the bottom 0! And to be honest i dont know if the ans are even kicking in or not i barely can tel so guessing they dont come on! pleasse help!

 

[Ictoanuk]

Hi i have a very similar problem where my car oil temperature doesnt rise when im driving and moving but when i am staionary for few mins t reaches 90 but as soon as i start moving it starts to drop and hits the bottom 0! And to be honest i dont know if the ans are even kicking in or not i barely can tel so guessing they dont come on! pleasse help!

First off, do you mean oil temperature or water temperature? AFAIK there isn't an oil temp guage (at least there isn't on my 150 V5) unless you have fitted an aftermarket guage?

As with the suggestions to the OP, if it is in fact the water temp you are referring to the guage moving between 0 and 90 tends to indicate the water temp sender is faulty. Cheap enough to replace but a bit of a pain to do.

Also, if it is the water temp, the thermostat may be stuck open but I'm not convinced that the temp would stick at 90 when stationary, it may go higher.

HTH,
Tim

 

[romeo]

Hi yes sorry mate not the oil temp gauge but the coolant gauge sensor! How do i change it and whats the part callled roughly how much?

And ive also got the mayo like stuff under my engine oil cap! hoe do i get rid of that?

 

[Ictoanuk]

Hi yes sorry mate not the oil temp gauge but the coolant gauge sensor! How do i change it and whats the part callled roughly how much?

I assume it is a V5 you have?
If so, it is located in the thermostat housing, under the engine cover, to the right, front, of the engine. Quite fiddly to remove, if unsure what you are doing get an expert to do it. Cost of the Temperature Sender is about £7.00, depending on where you get it from. Make sure you order a new C clip and O ring at the same time.

And ive also got the mayo like stuff under my engine oil cap! hoe do i get rid of that?

The mayo could be just a bit of condensation resulting from a lot of stop/start and short distance driving (give the cap a good wipe and take the car for a decent run so that the engine heats up fully), or worse case scenario, possibly the head gasket has gone or is on its way out. Remove the water bottle cap and check to see if there is any oil contamination in the water or bubbles coming up through the water while the engine is running. BE CAREFUL when removing the cap.

HTH
Tim