Leaking rad - Any DIYers to help Re & Re?

Muggins

Veteran Member
Joined
Jun 7, 2002
Location
Barrie, Canada
TDI
02 Golf GL 4dr 5spd
Noticed I was losing radiator coolant when the alarm sounded. No sign of leakage on the driveway. Since then, I've been adding coolant every week or so. Finally found wetness under the right-side bottom of the rad upon closer inspection.
Anybody out there who can help me remove and replace the radiator?
Thanks
 

amit9

Veteran Member
Joined
Oct 7, 2004
Location
Toronto/Scarborough
TDI
2003 Silver Jetta TDI GLS 5MT
I had the same issue at the same spot in my Jetta. I had it pressure tested and no leaks showed up during the test. I was also checking/topping it up every month just up to over the top line in the reservoir. Then I started to top it up to between the two lines and it's been ok since then. I check it once every month and the level is steady in the reservoir.
Have you done a pressure test of the cooling system? That's the best way to find out where the leak is coming from. There's also a flange at the bottom right of the rad, worth checking.
 

Muggins

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Location
Barrie, Canada
TDI
02 Golf GL 4dr 5spd
No haven't had it pressure tested. Are you saying you were losing coolant because you overfilled it at first? If so, where was your coolant leaking and why would it stop when you filled it between the minimum and maximum lines? I add coolant to between minimum and maximum lines and it eventually drops well below minimum before alarm sounds.
 

Johhny04

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Feb 21, 2006
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Markham, Ontario
TDI
2003 Jetta TDi
Under the right side bottom that you mention, do you see any green crud? My original rad had the development of these symptoms a couple of years ago. Due to rust and age, development of a leak. Common for MKIV. If yours is still the original rad, I bet you are having the same issue I had. Changing the rad is not that bad. Takes time. A couple of videos on the club and youtube helped with the process. I highly recommend you buy the rubber supports (4 of them, forget what they are called) that hold the rad in place. Due to age, they degrade.
 
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amit9

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Toronto/Scarborough
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2003 Silver Jetta TDI GLS 5MT
No the overfilling didn't cause the coolant loss, it was already happening before that. I filled it up to just above the top line for a couple of times, thinking that I won't have to re-fill that often. And the level still continued to drop slowly with wetness at the bottom right on the inside of the bumper. It's then that I decided to scale back on the re-fill level just a bit and see the results. And it looks like it has stopped falling, for now at least. This was in Spring and we had an extended cool period this year well into late May.
That's the thing, the pressure test and my looking at all over/under spots could not determine the source of the leak. My hunch is that an o-ring somewhere shrinks sitting overnight and caused a small gap. The first thing I noticed in the morning is a few drops of coolant on the cardboard under the bottom right side. Now that the weather has warmed up, the o-ring has expanded just enough to seal the gap. I think my issue may return in the fall...
 

Muggins

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Location
Barrie, Canada
TDI
02 Golf GL 4dr 5spd
I highly recommend you buy the rubber supports (4 of them, forget what they are called) that hold the rad in place. Due to age, they degrade.
Good point.

I just want to know why it would leak since it's aluminum which doesn't rust.
 

Muggins

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Joined
Jun 7, 2002
Location
Barrie, Canada
TDI
02 Golf GL 4dr 5spd
My hunch is that an o-ring somewhere shrinks sitting overnight and caused a small gap. The first thing I noticed in the morning is a few drops of coolant on the cardboard under the bottom right side. Now that the weather has warmed up, the o-ring has expanded just enough to seal the gap. I think my issue may return in the fall...
Seems odd why a pressure test would not reveal a questionable o-ring?
 

amit9

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Toronto/Scarborough
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2003 Silver Jetta TDI GLS 5MT
Seems odd why a pressure test would not reveal a questionable o-ring?
Possibly because the test was done by the shop when the car had been driven and the coolant was hot, that would've expanded the o-ring, not entirely sure about it tbh.
I will suggest a pressure test in your case, best done when the car is cold, will most probably tell you the source of the leak.
 

Muggins

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Jun 7, 2002
Location
Barrie, Canada
TDI
02 Golf GL 4dr 5spd
Yes, typical VW project - getting to the actual problem part is 90 per cent of the job. Seen a few videos - almost the entire front end needs to be disassembled to get to the rad.
I'd really rather someone who knows what they're doing with the correct tools, do the job, and I can help. At least I don't have to worry about the condenser since it doesn't have A/C.
Are there really no DIYers who could help?

 

P2B

Top Post Dawg
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Jan 11, 2006
Location
Toronto & Muskoka, Canada
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2002 Jetta, 2003 Jetta, 2003 Jetta Wagon
The radiators tend to develop slow leaks between the aluminium core and plastic tanks. Mine has been leaking on and off for 5 years now, sometimes it will go months without loosing any, then all of a sudden dump 500ml in one shot - usually in winter when I park with a hot engine in very cold temperatures. I keep telling myself I'll swap it out in spring but haven't gotten to it...

It's quite an easy job except for the fact the bumper cover and lock carrier fasteners get rusty in our winters and usually at least one of them will strip or break. Spraying them with penetrating oil for a few days before attempting disassembly will help.

There's a good guide for putting the lock carrier in the service position here:

http://pics.tdiclub.com/data/500/Radiator_mounts_install_guide_v2.pdf

Once that's done everything is easily accessible. I use M8 × 150mm bolts from Brafasco to support the lock carrier.

I'd offer to help but I'm not exactly around the corner from you.

Simon
 

Muggins

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Joined
Jun 7, 2002
Location
Barrie, Canada
TDI
02 Golf GL 4dr 5spd
The radiators tend to develop slow leaks between the aluminium core and plastic tanks. Mine has been leaking on and off for 5 years now, sometimes it will go months without loosing any, then all of a sudden dump 500ml in one shot - usually in winter when I park with a hot engine in very cold temperatures. I keep telling myself I'll swap it out in spring but haven't gotten to it...

It's quite an easy job except for the fact the bumper cover and lock carrier fasteners get rusty in our winters and usually at least one of them will strip or break. Spraying them with penetrating oil for a few days before attempting disassembly will help.

There's a good guide for putting the lock carrier in the service position here:

http://pics.tdiclub.com/data/500/Radiator_mounts_install_guide_v2.pdf

Once that's done everything is easily accessible. I use M8 × 150mm bolts from Brafasco to support the lock carrier.

I'd offer to help but I'm not exactly around the corner from you.

Simon
I've gotten to removing the expansion cap to relieve pressure after drives which I think reduces the amount of coolant lost - at least after parking.

Thanks for the link and your experiences with this problem. Seems rather fiddly and torturous removing all the peripherals required before gaining access to the actual problem part -- the rad. I can see myself breaking plastic bits and trying to take shortcuts which would totally frustrate me. That link is superb in its detail. Why don't you come up to Barrie and help me with this?
 

amit9

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Oct 7, 2004
Location
Toronto/Scarborough
TDI
2003 Silver Jetta TDI GLS 5MT
With the recent cool down in temps, this problem came back, this time it was leaking almost every time I parked. I got it replaced this week at a shop. Below are some pics of the job and the rusted out radiator.

Front of car removed:


Driver's side bottom corner, it's rusted out and there's a big gap, that's where it all started:


Passenger's side bottom corner, rusted out as well:
 

P2B

Top Post Dawg
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Jan 11, 2006
Location
Toronto & Muskoka, Canada
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2002 Jetta, 2003 Jetta, 2003 Jetta Wagon
Good grief, why on earth would you remove the front of the car to replace the radiator !?!

All you need to do is put the lock carrier (aka rad support) in the service position.

Simon
 

amit9

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Location
Toronto/Scarborough
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2003 Silver Jetta TDI GLS 5MT
Good grief, why on earth would you remove the front of the car to replace the radiator !?!

All you need to do is put the lock carrier (aka rad support) in the service position.

Simon
That's what 2 shops told me that the whole front needs to be removed to get to it, hence the labour cost on this job is high. Parts cost around $200-$225. I did check a couple of youtube videos and apparently that's exactly what was shown in those videos.
 

P2B

Top Post Dawg
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Toronto & Muskoka, Canada
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jayb79

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Location
Exeter,NH
No need to take the front end off just put it in the"Lock Carrier Service Position",as P2B stated above. Not hard to do just a lot of bolts to remove, getting the plugs disconnected is the hardest part.
Also some info here: https://forums.tdiclub.com/index.php?threads/how-to-lock-carrier-service-position.241307/
At around 3:00 this guys pulls the front away so you have an idea of the room it gives you.

With all that being said I just took the o-ring out of my radiator cap so my system doesn't build any pressure and its been that way for months without any trouble and the leak stopped. (Don't do this if you have any kind of tune, but fine with a stock diesel)
 

Muggins

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Location
Barrie, Canada
TDI
02 Golf GL 4dr 5spd
With all that being said I just took the o-ring out of my radiator cap so my system doesn't build any pressure and its been that way for months without any trouble and the leak stopped. (Don't do this if you have any kind of tune, but fine with a stock diesel)
What radiator cap? Do you mean the expansion tank cap?
 

TDI MkIV

Member
Joined
Jun 19, 2020
Location
Ontario, Canada
TDI
2004 Jetta Sport TDI PD
Good grief, why on earth would you remove the front of the car to replace the radiator !?!

All you need to do is put the lock carrier (aka rad support) in the service position.

Simon
Oops... I did the same thing. Oh well, the radiator is replaced now, no leaks. :)
 

P2B

Top Post Dawg
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Jan 11, 2006
Location
Toronto & Muskoka, Canada
TDI
2002 Jetta, 2003 Jetta, 2003 Jetta Wagon
I still didn't get around to changing my radiator before it turned cold, fixing split CV boots before winter took priority.

I've taken to releasing pressure in the cooling system when I arrive at the cottage, haven't lost any coolant since I started doing that.

Simon
 

burn_your_money

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Oct 16, 2012
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North Bay, ON
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99 Beetle, 96 B4V, 05 Passat wagon
The proper time to pressure test a cooling system is when the engine is completely cold. At the shop we always let the trucks sit overnight and then test them out in the yard before starting them. It often only takes a few minutes of run time for the leak to stop and then it's near impossible to find.
 
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