overheating and new thermostat

[Dacabbie]

:zx11: I have just had a new thermostat put on my vw passat tdi 130 ,but the car is still overheating and now the heating is not working at all,anyone have any ideas what else it could be please.?:aargh4:

[new to vw]

are the hoses hot top and bottom of rad????.......could be blocked rad???
lee

[Huweth]

Sounds like the common dreaded water pump failure to me. :(
The pump impeller is plastic on a metal shaft. The impeller becomes loose and doesn't spin on the shaft, hence, no water pumping. The impeller can also break. This will be a costly fix as the front end has to come off just like for a cambelt change.
Tell us more detail on the symptoms and we will try and diagnose it. There are plenty of members here who have had this problem, so we should be able to get it right. Don't book it in just yet for the water pump change as I could be wrong.

[RickT]

sorry to say... water pump mate...

Start the car.. top the coolant up if low.. remove the cap and watch the coolant.. if it pulses.. ie moves up and down when water is flowing its not the pump.. if still... pump...

note the theromsat wont open till about 90'c.. so once opto that temp keep watching..

RicKT

[Dacabbie]

To hewith Thanks for the reply,Jeeze hope it is not the pump as have just had to pay out for fly wheel, clutch, p a s pump and a few other bits. To expand on other symptons only overheats (110c - 120c) when being driven and come back to normal (90c) when idling at lights etc. If driven fast or hard warning check coolant light illuminates!:zx11: I've also noticed that the heating has started to work again yet goes cold when the needle starts to rise. I hope that you can understand all this and would be really grateful for any further advise.Thanks everyone for answering.:beerchug:

[MalcQV]

:( Tend to agree with the above, sounds like the water pump.

[Huweth]

To expand on other symptons only overheats (110c - 120c) when being driven and come back to normal (90c) when idling at lights etc. If driven fast or hard warning check coolant light illuminates!:zx11:

The impeller in the pump is gripping enough to pump at idle, but when it tries to spin faster as you drive, it looses grip and can't pump.
It's going to cost a few hundred quid to fix, and you might as well have the cambelt and tensioners done at the same time as it has to be taken off to change the pump.
Sorry for the bad news!

[Dacabbie]

Thanks for that info,it all makes perfect sense now, i'll pass it on to the garage and hopefully they can fit a new water pump.(ps already fitted cam belt,tensioner etc when pas pump was done 2 months back)but thanks anyway.
pps The car's been running really well for nearly 2 yrs right up until Dec 06.Since then have spent £1800.:aargh4: Ouch!

Once Again Many Thanks:beerchug:

[Huweth]

Hopefully you will have many trouble free years to come.
It's worth having the pump done at every cambelt change, it's only an extra £30. Also, there are pumps with metal impellers that shouldn't fail, so if you or the garage can get one, fit that.

[randall977]

The other option is the head gasket - the symptoms would tie in. The faster you go the more hot gas gets into the coolant. Are you loosing any coolant? Is there dirt in the header? When my water pump went my temp still stayed at 90 but the heating stopped. If a lot of gas is getting into the water it can stop your heating by causing an air lock. I guess you have already checked your cooolant though. The fact you have recently changed your pump makes me suspicious that it's not the pump? Thermostat? - Unlikely. Hope you get it sorted!

[RickT]

how did you get on with this?

RicKT