Poorly Polo running a temperature

[side-show-bob]

Hi All

This is my first thread on here so hello..

I have a 97 polo 1.4 petrol, and it is overheating. I have checked the coolant and there is plenty. I have noticed that the fan is not kicking in at all and there doesn't appear to be any circulation round the system when the engine is running, but when i manual pump one of the pipes you can hear and see the coolant moving in the expansion tank. I think the coolant pump may have gone but i would like some advice to help prove this.

Do i have to remove the cambelt to get to the water pump? Is there a way of checking the pump before removing the belt if it has to come off?

Cheers

Rob

[Crasher]

More common is failure of the thermostat housing upper cover. With the engine cold, remove the upper cover (it is at the end of the top hose on the black plastic water housing bolted to the side of the head) by removing the two 8-mm headed self tapping bolts. Turn the cover over and inside you will see a bridge between the two sides of the outlet. In the middle is the point where the pin of the thermostat reacts and if you can see a hole right through this, it is broken. If the thermostats pin can't push against this, the thermostat won't open. The part number should be 032 121 121 J and it costs £11 from VW.

[side-show-bob]

Spot on i have just removed the thermostat hosing and it is broken. Just one thing should the thermostat come out in three pieces, a plastic housing with spring, a brass part and the needle? or should it all be one.

Cheers

Rob

[Crasher]

You need a new thermostat as well, 032 121 110 B at £9.40 and an "O" ring 032 121 119 H at £2.37 which I forgot about earlier.

[bingo23]

Hello again Crasher

I think my polo may have this problem with the thermostat too.

After starting the engine, the temp needle never moves very far off the bottom, just to the first mark.

Then after driving around for some time, then stopping in traffic, the needle quickly begins to rise.
starting driving again, lowers the needle.

But one more anomaly is that when ever I open the coolant reservoir, i find it empty, but I cant find any evidence of any leaks anywhere, and it appears to be under pressure even after engine has been cold for days.

Would you think its just the thermostat or maybe something else as well?


thanks again

[Kookoo]

bingo23, if you find a way to resolve your issue - please post it, because I am having exactly the same problem.

[Crasher]

Bingo, I would expect you to find no thermostat when you remove the cover. This is the solution employed when people can't work out what is wrong. Late in 2006 I bought a Seat Cordoba for my father in law as it was going cheap because the garage selling it was struggling to get the heating to work and the engine to run correctly. I warmed it up and read the codes which only showed a lambda sensor error. I took it for a run and the temp gauge started falling and by the time I got back it was right down at the bottom of the gauge. I stole the car off them for a lot less than it was worth, brought it back, fitted a new thermostat and cover and all was well. The lambda sensor was dead though, the ECU had been fuelling the engine to match the temp sensor and the lambda sensor was black.

[bingo23]

Thanks Crasher, I will investigate the thermostat - should I be looking for a lambda sensor too? - didn't think i had one of those :confused:


I will get the parts and replace as you suggest - same 3 parts as in your posts above?

On the plus side, as the coolant keeps disappearing I don't think I will have to drain the coolant to change the part.


Do you think this fault would explain the coolant disappearing as well somehow, or should I still be looking for a leak somewhere?

thanks

[side-show-bob]

Cheers Crasher

I have replaced the three parts and it is still overheating....
I have checked the reservoir and it is still holding the coolant, all the pipes except the one leading from the thermostat to the bottom of the rad are hot but still the fan is not kicking in.. Any ideas of where to start looking?

Also whats the best way to refill the cooling system?

Cheers
Rob

[Crasher]

OK, I thought you were going to check the cover and report back, never mind. The next step is to pull out the water pump and check the condition of the impeller. Also check that it is still tight on the shaft.

[moomin-papa]

Hey,

I'm having similar problems on my 1.6L '97 MK3 golf, I know this is a polo forum but am I correct in assuming that the 1.4L and 1.6L polo engines are the same as used in the golf?

I also heard that these engines have the same block so I'm assuming the part numbers for a new thermostat and cover would be the same as quoted above?

Thanks!

[side-show-bob]

Ok so i filled up the system and removed the rad hose, started the engine and the water flow changed so i am assuming the pump is working. I removed the thermostat and it apears to be running fine now.. why would this be???

[Crasher]

Did you fit a new thermostat cover? The top bit that the hose attaches to?

[side-show-bob]

Yes i have replaced the top cover, o-ring and a new thermostat..

[Crasher]

So with no thermostat in it doesn’t overheat? Don't drive it like this, it will over cool.

[side-show-bob]

Will it damage the engine if run without a thermostat for a short time? any ideas why it wont work with the thermostat in?

Cheers
Rob

[Crasher]

It will over cool, the ECU then puts in too much fuel (via its info from the coolant temp sender) which shuts down the lambda sensor and then the ECU puts in more fuel, kills the catalyst and finishes off the lambda sensor whilst washing the bores free of oil which makes the rings run dry. IF it is flowing with out the thermostat it can only be the water pump which is just moving enough water to cool it with the thermostat out. Is the heater staying hot? I had one like this Friday, a new pump sorted it out but he had been running it without a thermostat for a few days. Now he needs a new catalyst and lambda sensors (a later EU4 emissions car with pre and post cat sensors).

[side-show-bob]

The heating is not getting as hot as it normally would, it is staying at a constant warm temp. Will try replacing water pump and see if that sorts it out!

Thanks for your advice.

[bingo23]

sorry to have hijacked your thread sideshowbob, i thought yours had been resolved, my problem is similar but I'll start my own thread. good luck with yours.

[side-show-bob]

I have removed the water pump and it is tight on the shaft, the impeller is in good condition, in fact it looks nearly new. Any new ideas I can expolore...?

Any help gratefully received!

[Crasher]

That is not good news.

[side-show-bob]

I have traced the wiring for the fan and i am getting 12V to the rad switch and the two wires coming out of them are both fine, the earth on the fan is good and the fan runs with 12V applied. Could it be the rad switch that is causing problems?

[Crasher]

I didn't think you had any circulation?

[side-show-bob]

The fault as it stands is as follows;

When the system is complete with the thermostat in place the pipe from the bottom of the rad stays cool whilst all the others get hot. I have checked the system using a hose and water is flowing round the block and through the Rad. The temp can reach 110c and the fan doesn't start. The heater blows out hot air.

With the thermostat removed the temp stays at around 70c and the heater blows out warm air not as hot as usual. The fan does not run either but i am assuming its because the temp is not getting hot enough.

Can i test the new thermostat, i know i used to test landy ones in a pan of water and as it began to boil you could see it moving, can you do something similar with these?

Cheers
Rob

[Crasher]

That does sound like a faulty thermostat, where did it come from?

[side-show-bob]

I got the Thermostat from GSF

[Crasher]

Well all I can suggest now is a genuine part. Is the reaction bridge of the new cover OK?