Jetta 5 TDI overheating woes!

[Callum229]

Hi therei have a 2007 Jetta 5 TDI(1.9 BXE) DSG that has been almost a nightmare from the time I got 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).

Can anyone shed any light on this, if combustion gases was leaking and entering the coolant, surely it should become dark over time or form soot spots, the only thing that it seems to have is a few rust flakes and it just smells like coolant.

When it starts ejecting water due to pressure, it smells only like boiling coolant and the return gives off some foam, then when it settles, water starts flowing smoothly.

I am getting the headbolts checked and tightened to another 1/4 turn. If it stops ejecting coolant or being under that much pressure, it should mean that the head gasket is on its way out, right?

Further more, should I get the head skimmed when replacing the head gasket? I heard that you shouldn't be skimming the 1.9 TDI heads.

This is turning into the most expensive project that I have ever undertaken!

[Trishen94]

Hi therei have a 2007 Jetta 5 TDI(1.9 BXE) DSG that has been almost a nightmare from the time I got 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).

Can anyone shed any light on this, if combustion gases was leaking and entering the coolant, surely it should become dark over time or form soot spots, the only thing that it seems to have is a few rust flakes and it just smells like coolant.

When it starts ejecting water due to pressure, it smells only like boiling coolant and the return gives off some foam, then when it settles, water starts flowing smoothly.

I am getting the headbolts checked and tightened to another 1/4 turn. If it stops ejecting coolant or being under that much pressure, it should mean that the head gasket is on its way out, right?

Further more, should I get the head skimmed when replacing the head gasket? I heard that you shouldn't be skimming the 1.9 TDI heads.

This is turning into the most expensive project that I have ever undertaken!

Where do you live ?
Tell us your location then we can direct you to a proper mechanic who knows what his doing

[Jetta2]

I am getting the headbolts checked and tightened to another 1/4 turn.

Whoever told you this does not know what they are talking about......

[Callum229]

Stay in Durban. Budget is a bit tight though. Since I spent all if not most money on the car, I would have to do the head gasket myself.

Doesn't help that we in the middle of Corona Virus.

[warickwrx]

My 5c if its the head gasket which it most probably is you will need to factor in additional head skimming at engineers and replacement of bolts removed on the head etc etc. Further more if the mileage on the motor is high I would inspect the camshaft and lifters for wear while you at it. When head is off inspect pistons and valves as well. Do it properly the first time !

[Callum229]

Yep, that's what I want to do, mileage is about 118000 miles which isn't high at all for a TDI.

I think the previous owner bust the radiator, put a new radiator, and then called it a day.

The engine cooling system was a combination of silicone, many water leaks and clogged pipes. Only once that was repaired, then I discovered it's spewing coolant. Now with all that gunk that was inside, I'm not sure if it's clogged in one of the water passages or it really is the head gasket.

It's just that I spend a crapload of money already, and don't have the money to throw at a head gasket only to find it isn't the cause.

I have tightened the head bolts 90 degrees (quarter turn). Hopefully that prevents any more coolant spewing, then I know it's the head and prepare myself to redo the head.

Will update shortly on how that went.

[warickwrx]

The head bolts are stretch bolts you should not attempt to try over tighten them they could snap off on your head and you will have bigger problems. Having said that there is also a tightening sequence that needs to be followed if you end you up replacing the head gasket. If I was you I would try have a compression test done. Other option is for a exhaust gas coolant test. Dis you follow the correct procedure and bleed the system when you replaced the coolant ?

[Callum229]

Haven't done the gas test or sniffer test, but on forums it does say that it isn't reliable.

I am looking to get a set of ARP head bolts, only problem can't find any in SA. So I will be ordering from Darkside and hopefully with this pandemic, it should come soon.

I also tightened by 1/4 turn using the tightening sequence.

If the problem persists, I will definitely try a sniffer test, coolant pressure test and any other small tests before replacing the head gasket.

This car is my daily car, so I need to make arrangements before doing the head gasket.

I have tried every correct bleeding way, including putting a vacuum on the return line, massaging pipes, revving high to take out bubbles, I still have that same issue. The MK5 TDIs are self bleeding.

[Callum229]

UPDATE - So 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 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.

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?

[ES1987]

Have you noticed any water leaks in and around the car at all?

I had overheating problems with my 1.6 TDI as well. All the plastic fittings like the thermostat housing etc. had to be replaced as they had become so worn on the inside walls that they leaked water. Not sure if the heat had anything to do with the wearing out of the plastic.

I replaced about 3 different plastic housings as well as the water pump and now I don't have any issues with overheating.

[Callum229]

Hi guys, just an update, it was the head gasket and the head, the head was CORRODED as well as the ports corroded, so I got a used ASZ head instead of trying to aluminium weld the head and hoping it would work, the new head went on fine(had it "lightly skimmed", pressure tested and new valve seals with new hydraulic lifters as well), after 5000kms of driving, not a drop of coolant has been lost from the expansion tank, hoping she lasts a long time without any further issues!

Thank you to everyone for their input and help!