Jetta 5 TDI DSG spewing coolant out of bottle

Callum229

New member
Joined
May 21, 2020
Location
South Africa
TDI
2007 VW Jetta 5 TDI DSG
Hi there


I have a 2007 Jetta 5 TDI(1.9 BXE) DSG that has been almost a nightmare from the time I got it. It has around 190 000kms on it.

Now that most of the things are sorted, I still have an overheating issue.

It will eject water out of the coolant bottle and then go low on water, and sometimes it will overheat when pushing the car hard. When this happens, the heater goes cold and most of the water is dumped out of the bottle.

I have done the following so far.
- New coolant pipes.
- New transmission cooler.
- Flushed coolant about 5 times already with radiator flush.
- New bottle plus cap replaced twice(thought it might be the bottle not able to handle the pressure).
- New thermostat replaced twice.
- New waterpump(nothing wrong with the old one).
- Flushed both radiator and heater core.
- Found return line from head blocked, cleaned it and water is flowing now.
- Did an EGR + EGR cooler delete.

I now think it might be the head gasket, but I have never noticed any soot or any change in the colour of the coolant(it previously had some green coolant, I have flushed out and replaced with G12+ about 5 times).


I have had the headbolts tightened by 1/4 of a turn to see if it makes a difference.....



After doing that, the car still is doing the same thing, not as bad though(could be because I drove extremely slowly), however I noticed something extremely weird.

When you driving on the freeway, the heater stays on and constantly on, with hot air.

The temp on the freeway, sometimes it will go to 88 89 on the instrument cluster downhill, but uphill it will go back to 90.

However, slow down and go to idle, the heater dies away and cold air comes out.

However, temperature doesn't change at idle or below 2000rpm and stays a constant 90.

I cannot fathom what it is besides a circulation issue and maybe one of the return pipes are blocked, causing the foaming of the coolant with hard circulation. I have checked and cleaned the pipes about 3 times now and also used radiator flush around 5 times...

I suspect that the coolant isn't circulating fast enough, causing the engine to overheat at high load and boil the coolant and at low load, because of low circulation, coolant isn't flowing fast enough therefore the heater in the cabin is cold.


When I race uphill, it will not overheat, however, as soon as I slow down or go to idle, heater goes cold and it starts overheating...


Could also be some air stuck in the system because of that and that could also be contributing to coolant being boiled.

What do you guys think, what should be my next move? I want to avoid replacing the head gasket unless I am 100% sure.
 
Last edited:

Mozambiquer

Vendor , w/Business number
Joined
Mar 21, 2015
Location
Versailles Missouri
TDI
2004 VW Touareg V10 TDI, 2012 Audi Q7 V6 TDI, 1998 VW Jetta TDI. 1982 VW Rabbit pickup, 2001 VW Jetta TDI, 2005 VW Passat wagon TDI X3, 2001 VW golf TDI, 1980 VW rabbit pickup,
If you have the coolant cap off and start the engine, what happens? The best thing to do would be a combustion gas test, to check for gasses in the coolant. But it sure sounds like you have a head gasket issue.

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