03 Jetta TDI Leaking Coolant problem

[vavulaka]

Hi everyone, I'm new here so forgive my ignorance.

I recently bought an 03 Jetta TDI.

The man I bought the car from is a diesel enthusiast and took good care of the car. I've owned it since September 2012 and so far the only problem was a bad thermostat that I had to change in late September along with a new coolant temp. sensor.

Here is where I'm having problems:

A few months back I started getting the coolant indicator light on my dash, I would add some and it would go away for a few days, however these "fill-ups" became more frequent. The coolant reservoir seems to constantly be empty.

I've looked about to see if there are any leaks and did notice that I constantly have a "wet spot" underneath the passenger side headlight. I checked the reservoir itself to see if it had any cracks and it's fine. I can't find any hoses that are leaking or seem wet anywhere. The leaking seems to be confined to the area under the reservoir so I'm a bit confused as to what is going on.

I was told that it could be an air pocket somewhere since the coolant only leaks when the car reaches its ideal temperature. I also noticed that when the car is warmed up, the hose coming from the top of the radiator is very hard (under a lot of pressure it seems) this makes me think that perhaps there's a clog somewhere? Should I try draining the system?

Anyway, I hope you guys can help me out here.

Thanks!

 

[aja8888]

Take a look at the water pump under the timing belt cover. Sometimes when they are going out they leak from the bottom of the pump at the vent hole.

 

[vavulaka]

Take a look at the water pump under the timing belt cover. Sometimes when they are going out they leak from the bottom of the pump at the vent hole.

That was one of the first things I checked but there was nothing there..plus the timing belt was changed about 10k miles ago.

 

[AndyBees]

Also, re-check the two bolts for the coolant flange where the T-stat was replaced...could be leaking there! Happened to me!

 

[vavulaka]

Also, re-check the two bolts for the coolant flange where the T-stat was replaced...could be leaking there! Happened to me!

The flange seems totally dry.
Could there be clogs in the system?

 

[AndyBees]

That flange fooled me for about 1 gallon of $22.00 dollar G12 coolant. I removed the flange and there it was...........obvious leak. Even though it was a new Flange and O-ring, I goofed! I installed another new O-ring and then tightened the two bolts per spec..plus a little tighter.

However, if you feel comfortable that the Flange is not the problem ..........I now lean toward the Water Pump as others have suggested!

I doubt there is a clog in the system............. the closest thing to a clog would be a bad T-stat that is not opening when the engine reaches normal operating temp (about 87c or 190f).

 

[flee]

Hate to say it but, heater core?

 

[Alchemist]

Don't worry about the hose being hard. When the system is at operating temperature it is also under pressure, which will make all the hoses hard.

There is a metal tube coming out of the back of the water pump which can leak if the O ring is in poor shape.

Paul

 

[sy552]

Try putting some dye in the system and look with a black light.

 

[AndyBees]

Don't worry about the hose being hard. When the system is at operating temperature it is also under pressure, which will make all the hoses hard.

There is a metal tube coming out of the back of the water pump which can leak if the O ring is in poor shape.

Paul

Paul, (anyone), what's the part number on that O-ring?

And, yes, it can be problematic.....had that issue with my Vanagon TDI engine.

 

[vavulaka]

The problem is that it doesn't seem to leak from anywhere near the pump. It literally looks like it's somewhere underneath the reservoir.
When I drained the coolant to change the t-stat and sensor, I simply added coolant to the reservoir. I saw on here that you're supposed to take the top hose off of the radiator then allow the air to escape. I'm wondering if that created a problem.

 

[AndyBees]

The hose routing (large and small) works the air out without issue! The air is dumped into the resevoir.

 

[vavulaka]

The hose routing (large and small) works the air out without issue! The air is dumped into the resevoir.

So if the reservoir cap doesn't release that air properly could that cause that too much pressure and thus it'll start dumping coolant?

 

[AndyBees]

Possibly, but it would only dump enough to equalize the system. But, keep in mind, the system can reach up to 12 to 15 psi. I'm not sure what the pressure spec is on the lid.

I've had the coolant out of my ALH TDI in the VW Vanagon (long rad hoses to the front) several times recently and have not had any issue at all getting the air out.

I did an Engine Coolant Temp sensor change on Golf about a week ago and lost coolant due to it being too hot to handle. After cleaning up the mess, dumping in more coolant/water, started the engine and the air was out in less than 5 minutes.

I believe you have something else going on.

Let the engine idle with the cap off ..........observe to see if coolant is circulation into the reservior via the small black hose. If it is in fact circulating, any air in the system will be eventually dumped into the tank. The design is very good about purging the air out.

 

[Alchemist]

Andy

I found 06B 121 687 for the O-Ring. Hope it's right.

Paul

 

[Jettascuba]

Pressure test your system.

 

[Snizzbob]

I just had to replace the headgasket on my 03, it was doing exactly what yours is doing. It had a very small leak in the headgasket, and would over-pressure the cooling system and force coolant out the overflow of the reservoir, which will run down the frame rail towards the headlight. With the engine cold, does the upper radiator hose get hard almost right away? Do you have any black, oily looking soot floating around or coating the inside of the reservoir? With the compression these engines have you may not see coolant in your oil or smoke out the tail pipe, but you can be pushing compression into the cooling system.

 

[vavulaka]

I just had to replace the headgasket on my 03, it was doing exactly what yours is doing. It had a very small leak in the headgasket, and would over-pressure the cooling system and force coolant out the overflow of the reservoir, which will run down the frame rail towards the headlight. With the engine cold, does the upper radiator hose get hard almost right away? Do you have any black, oily looking soot floating around or coating the inside of the reservoir? With the compression these engines have you may not see coolant in your oil or smoke out the tail pipe, but you can be pushing compression into the cooling system.

Man........... everything you just said is exactly what I was seeing!!

On Thursday night I finally went over the entire system to try and figure out what was going on with the leak. I found that the lower radiator hose had a good size hole in if from rubbing on something, I replaced that.
However I later found that the head gasket was leaking right underneath the housing that holds the coolant temp. sensor. It's not a big leak, but it was producing a "mist" like spray.

I thought about changing the gasket myself, but I decided to pay up and take it to someone who knows what they're doing. I asked around and found a guy in Philly who specializes in European cars and diesels. He has a big shop in Philly and ironically enough he gave me the best price ($500 for labor and parts) Hopefully that price won't go up, but who knows if other things will need to be replaced.

I should have figured out that the gasket was bad when kept having horrible cold starts and a lot of white smoke in the morning start. I was promised that everything should be fixed by Tuesday or Wednesday. I'll update you guys on how things go.

 

[PeterV]

click on the trusted mechs on at the botton of my sig. You really need a GURU and htere is a master GURU not far from you in Red Lion.