Is it time to change heater core ?

Hi there,

I took my VW passat b5, 2000 year, 1.9 diesel to local garage. They done flush for cooling system (including, heater core and cooling radiator etc.) changed thermostat. But the heat is really poor and when I am driving fast above 100km/h it slowly gets colder and colder.

Is it plugged heater core?

This thread may provide some useful info http://forums.tdiclub.com/showthread.php?t=423997

I took my car to local garage, they took off two heater core pipes and there were no pressure at all (even when car was on) so we couldn't figure out what could be a problem.

could be bad water pump ? Water pump was changed 4000 miles ago.

Also I checked temperature with VCDS lite, sometimes it showed 98C, 93C and then 90C(when car was not driving)

What could be a problem ?

Do you mean you could blow through the core wit no resistance?
Or the engine would not pump water to the heater hose?
Not sure how you could measure pressure in the heater water loop?
Was the heater core air bled proper?

peiphil said:

Do you mean you could blow through the core wit no resistance?
Or the engine would not pump water to the heater hose?
Not sure how you could measure pressure in the heater water loop?
Was the heater core air bled proper?

Click to expand...

When mechanic took off the two houses (two houses what cconnects the heater core) there weren't pressure at all even when car was on idle.

Well in garage where they done flush for cooling system they said that they done air bled... also in other garage (where I went yesterday) they done air bled as well.

It sure sounds like a bad waterpump. The garage should be able to pull the thermostat and check to see if the waterpump impeller is loose on the shaft.

To do that they ask me about 100 quid (about 200$) which is to expensive.

I am thinking to change antifreeze again (as the new antifreeze become really dirty not in a pink colour after a week driving), then I will try to check waterpump if it possible at all ?

The pipe what goes from engine into the cooling radiator (the big radiator on the front of the car) is cold, is not even warm when engine temperature is 90C when I done some bending(squeezing) on that pipe, my heating temperate has improved, I had warm heat.. so I think the big radiator might be faulty, because the bottom side of radiator where the pipe goes in it's cold.

I would be happy to have that heating for longer period, because once I am on motorway the warm heating goes away..

is there any option that I can check on VCDS-lite about heating ? like faulty codes etc. ?

100 quid is too much to check the water pump. Two bolts and the thermostat comes out then they can just reach in and feel the water pump. If you are going to change the coolant, that is the percect time to do it.

I got heating but not the best, but it's okay for current outside temperature. I changed cooling tank lid (thought it can be something wrong with that, also someone told me that)

I did found out that if I drive in high rmp my heating is getting warmer and warmer... what could be that ?

First guess is water pump. But it appears that yo are looking for a different answer so, I'll say thermostat. Or heater core. Or radiator.

Take your pick, but choose something and test it to verify.

Thermostat has been changed, about 1000 miles ago, if the big radiator is plugged then my car would overheat ?

OK, the thermostat was changed. Is it working?

Yes I think so, the old one was stuck and the new one opens and closes as far as I know, as I don't get less than 88 and more than 92C usually.