Hi all, friday just gone, was driving to work and my cooling light came on and beeping etc, i looked at the gauge and the temp was just below max 130 degrees, so i pulled over about a mile later looked under the bonnet and everything looked fine. Started the car and the temp was at 90 degrees again strange, drove about a mile again and it went all the way up to max again.

So thinking it was the thermostat i replaced that and also noticed the fan wasnt coming on so i tested it by bridging the connections so it was on full and then drove for about 15 minutes last night and the light came on again.

So i was thinking why isnt the fan coming on and i checked the pipe that comes from after the termostat to the bottom of the radiator and it was cold, strange?? I have tested both my old thermostat and new thermostat in a pot of boiling water and they do open.

So the next thing i have tried is to remove the thermostat completely and now that pipe is hot but the fan still isnt coming on, so i guess i do need to replace that sensor but im not sure if it was the waterpump,

I would of thought that if the waterpump wasnt working then the water wouldnt be getting to the radiator even without the thermostat?

Any help would be great

Thanks

If your waterpump isnt working, there would be no hot air through the vents.

 Funny as i have exactly the same in my 110 gt tdi and light comes on and buzzer tells me to stop,car cools drive it further and it goes right back up to 120-130,scary!

Have been told it's the waterpump,there is no hot air through the vents although the system is pressurised and the cooling fans both work,so am getting it to a garage asap!

ok just come back from a 30 minute drive both ways, without the thermostat and its a nice warm day, i obviously still got a issue with the fan but ill buy a new sensor to see if that sorts that out, but the journey out and the journey back the warning didnt come on and the temp stayed at a steady 90 degrees so i dont know.

But are you saying the internal heater wont work if the water pump does not work???

I thought the internal heater had its own system???

When i poked my finger down the hole where the thermostat was i could feel the waterpump fan and it wouldnt move and felt intact but obviously i couldnt do this test if the engine was running or id lose my finger

Any other ideas?

strange just saw the cooling fan have a quick spin, but definatly no internal heating and its been like that for months didnt really think anything of it before

g60dave:

 

But are you saying the internal heater wont work if the water pump does not work???

 

Yup you wont get hot air blowing, only cold. if it is the waterpump, you might want to have your cambelt and tensioners done too, as this is what VW recommend.

yeah thats for sure, okay i just undertook the job of blowing through most of the pipes just to make sure there was no blockages, and then was planning to put the thermostat back and i just felt the impeller and its still intact but i can spin iteither way a bit, should i be able to do that? or should it be fixed as it is still on the timing belt etc?

The spindle is the part that usually breaks in the vw waterpumps. Its made out of plastic for some ridiculous reason. So you would still be able to turn it as the impeller is still in in its housing, but I would guess that it should be fixed as its on the timing belt - but thats my two cents! Ive never felt a broken waterpump.

Mate, I would have it diagnosed by a mechanic, because you wouldnt want to change all the bits to realise thats the problem is somewhere else. Until someone looks at it, you're fishing in the dark

Very True, im just hoping a mechanic might read this and tell me their thoughts before i start ringing round tomorrow

other then that im tempted to put it back together again and see if it starts to overheat again, but hopfully someone here will tell me which direction to go?

Sounds like the pump to me. The (plastic) impeller cracks causing it to slip on its shaft. The coolant will still circulate around the system by convection, but obviously not at an adequate rate.

 Is the water pump driven by the cambelt? Most modern cars that have cambelts seem to be, but I don't know about G60's

The symptoms described sound like no circulation which could be caused by blockage (pretty unlikely) an air lock in the cooling system or sheared water pump.

If it's a sheared water pump and the pump is driven by the cambelt then don't drive it. I've seen plenty of cars that have had noisy water pumps sieze and strip the cambelt of teeth and the valve timing goes out and it's huge bill time.

If the water pump is driven by an auxillary belt it's still not a good idea to run the engine with no circulation as excessive heat and pressure in the cooling system can lead to bills even bigger that cambelt's slipping or snapping.

My advise would be to check the cooling system has had all the air bled out properly and run at a fast idle watching the temp gauge the whole time, the fans should come in at around just over the half way mark. If the water is still not circulating you might find that the water temperature actually on the rad fan sensor might not be as high as within the block or at the temp gauge sender so check the coolant pipes by hand (engine off obviously) and they should all be of a similar temperature.

Can't think of anything else off the top of my head...

g60dave:

Very True, im just hoping a mechanic might read this and tell me their thoughts before i start ringing round tomorrow

there you go!

Ismond:

Sounds like the pump to me. The (plastic) impeller cracks causing it to slip on its shaft. The coolant will still circulate around the system by convection, but obviously not at an adequate rate.

Mine is in the garage as we speak with similar symptoms, and im told this is the fault, common problem apparently. I could hear a rattleing noise when i drive also which would make sense if it was a damaged impeller. Ill post up when i get the car back, the garage quoted in the region on 250 - 300 quid to repair inc labour and parts.

 I had the waterpump, temp sender and thermostat (housing and all seals) changed, when my V5 overheated. It used to be fine and then 2 times it just used to go up to 110'C and the coolant used to boil vigourously! Overheating can cause serious issues further down the line, so its best to get it fixed and just bear the cost.

Cost me £260 all in to get that all done from a family friend at his garage. The VR engines are chain driven, but for every other engine you may aswell get the cambelt changed as most of the labour is already done when the waterpump is removed.

 Ok, got the car back from the garage, it was clear that the water pump had failed, the impeller was split in two, the place i use to get my car done change the water pump on golfs during every tming belt change purely becasue the part is cheap rubbish (so much for german build quality again eh?). Anyway, the cost of the repair was £315, Pump, belts, tensioners, fluids and labour. The car is now running good. Just hope that when my temp guage went up it didnt do any other damage that may appear at a later date such as the head gasket. I managed to catch it quite quick though so hopefully all should be good.

good to hear, ive got the rest of the week off so just been down euro car parts picked up all the bits and will undertake changing the waterpump and belts, so ive got a few days to play with, wish me luck!

 All sorted then...

It sounds like you were keeping an eye on it so you should be OK head gasket-wise.

Most head gasket problems come from cars that overheat then appear to cool down, when what actually happens is the car overheats, then the water boils and over pressurises the cooling system which releases the over pressure along with half the coolant, this leads to a drop in coolant so that the temp gauge sender hasn't got coolant on it and is reading from the steam, the driver keeps driving until either they stop, the engine siezes or it starts missfiring, any one of these scenarios isn't a good one.

My advise would be (once your happy it's not loosing coolant etc) is to go for a good drive and work the engine quite hard, keeping an eye on things and check the coolant level when you've finished (usual precautions taking cap off etc)

I've known a few cars to be fine when driving around normally but gasket leaks of cracks open in head when pushed. For peace of mind take it to a friendly garage and get them to check the coolant for exhaust fumes, its a very simple test, usually 5 or 10 quid but worth 50 quid in peace of mind.

I would do as you're doing, change the pump, belt and tensioner(s)

My mate's AGU A3 had the seizing water pump problem, then it seized the w/pump pulley rather than breaking, resulting in belt slip and wear, lost a few cambelt teeth and that was it, engine went out of timing and.... well you can imagine what happened.

Chris.

Well all work has come to a halt as im waiting for VW to get me some new engine mounting bolts which should turn up tomorrow, only thing im not sure about is how to hoist the engine up, obviously i havent got a engine lifter so how else can i do this?

yep it was the dreaded water pump, when i took it out the impeller had a crack small down it, so i guess at low speeds the fan probably worked but at fast speeds it probably  couldnt spin properly! but i changed timing belt fan, aux belt and a few of the engine mounting bolts,  and my internal heating is working again!

Only thing is i havent seen the radiator fan spin but couldnt be it hasnt got hot enough yet, we shall see over the next few days

 The radiator fans not spinning could be due to the common fault whereby the resistors burn out. See this if you haven't already: http://uk-mkivs.net/forums/t/59897.aspx