Coolant Leak

WolfgangVW

Veteran Member
Joined
Oct 16, 2011
Location
Alberta, Canada
TDI
2003 Jetta TDI - Manual
Hey all. I seem to have a coolant leak but not sure where from. It's leaving a puddle under the car, seemingly dripping down the back of the engine somewhere and dripping on the ground from like where the oil drain plug would be. I still have yet to crawl under and investigate but just wondering if anyone has any input as to what to first check given the location. Thanks in advance!!
 

STDOUBT

Veteran Member
Joined
Jul 30, 2007
Location
Portland, effing Oregon
TDI
tres jettas
The only coolant leak I've ever had was at the temp sensor. Leaves a puddle on top of the transmission case.
If it makes it down to the belly pan, it can go from there to the ground at pretty much any point, depending on which way the pan is warped.
You might find this of interest:
 

STDOUBT

Veteran Member
Joined
Jul 30, 2007
Location
Portland, effing Oregon
TDI
tres jettas
Dangit. I have to take that back. My water pump pooped out a while back. I guess I blocked that out lol it was only 60k 70k miles in.

🙈
 
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Bhavick

Veteran Member
Joined
Jun 25, 2018
Location
United Kingdom
TDI
1.9TDI
I had a recent coolant leak but mine was on the right hand side of the engine, it was leaking out of the coolant flange and dripping down on to the gearbox. I initially replaced the temperature sensor but it still continued leaking, turns out the coolant flange was broken inside where the o ring sits. I replaced both with genuine OEM items from darksidedevelopments and it's been fine ever since. Hope you get your car sorted (y)
 

Shenandoah

Veteran Member
Joined
Jan 9, 2008
Location
Shenandoah Valley, VA
TDI
2005 Jetta Wagon; 2005 Beetle; 2004 Jetta; 2002 Golf (three of them); 2002 Jetta Wagon; 2000 Audi TT->TDI; 1999 Beetle
I'll second what others have said: Could be the coolant flange on the side of the cylinder head. I've replaced them on two of my 2.0l gas and just replaced one on my 2004 BEW. They all had a small crack and leaked coolant down the back of the engine. For the 2.0l I found an aluminum replacement. Couldn't find an aluminum one for the BEW so I went with the plastic one again.

Eric
 

Genesis

Top Post Dawg
Joined
Feb 26, 2003
Location
Sevier County TN
TDI
'03 Jetta Wagon
Also check the splitter at the top driver side (which connects to the coolant reservoir bottle); that plastic "T" on the small side can fracture inside the hose and is rather non-obvious. Its cheap and available at local parts stores, believe it or not (Dorman makes a replacement) but if it blows out on you entirely you're going to have a bad day.
 

WolfgangVW

Veteran Member
Joined
Oct 16, 2011
Location
Alberta, Canada
TDI
2003 Jetta TDI - Manual
Thanks for all the replies. I’ll have a look in the next day or two. It seems like it may have a continuous small leak. Like even if the car sits for 5 days it will still drip adding to the puddle. I did the coolant flange and the T-stat and CTS all way in the past and it seems like then it only dripped a little then stopped after the car cooled down. But I may be wrong too !
 

Genesis

Top Post Dawg
Joined
Feb 26, 2003
Location
Sevier County TN
TDI
'03 Jetta Wagon
Yep -- particularly if you had a fuel leak from the pump head seal in the past it likes to drip right into that space, and diesel will eat that seal over time.
 

WolfgangVW

Veteran Member
Joined
Oct 16, 2011
Location
Alberta, Canada
TDI
2003 Jetta TDI - Manual
So the coolant leak seems to have stopped ! I couldn't find it, even took it to a mechanic friend as well who couldn't track it down. It's weird! Originally leaked enough coolant I topped it up before taking it to him but it's at the same level. Strange enough it seemed to leak parked and then under pressure or not it completely stopped ! any suggestions!?
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,glutton for punishment got another tdi 2001NB,another yellow tdi NB
Look around for pink crusted areas.
My daughter had a leak on her 03 NB.
On her car it was the hose just behind the clamp , it developed a pin hole that leaked.
 

94cobra2615

Veteran Member
Joined
Jun 16, 2013
Location
ohio
TDI
2002 Black Wagon
I've had success using coolant dye.
Dump the dye in the coolant and drive it for a day.

Then at night get a simple blacklight and look for the leak. Makes it a lot easier to find a tiny leak.
 

U4ick

Veteran Member
Joined
Nov 16, 2014
Location
texas
TDI
2003 jetta tdi
I've had success using coolant dye.
Dump the dye in the coolant and drive it for a day.

Then at night get a simple blacklight and look for the leak. Makes it a lot easier to find a tiny leak.
This is what I did to find a tiny coolant leak that was dripping from around the oil plug area.

Found it the night after adding it with an ultraviolet flashlight after searching for it for weeks.

Turned out to be a tiny seepage from the seal of an aluminum manual transmission coolant flange.

I realized later that I had caused it by r&r ing it when replacing seals on the vacuum pump, when I put it back on I tightened it unevenly by hand without using a torque wrench. That torque value is 7 ft.lbs. and should not be over tightened.

The only drawback is that the dye reacted with my pristine light pink coolant and turned it to a nasty sewer water brown.

After many flushings involving shop vacs, water pumps, air pressure, etc. I am resigned to the fact that my coolant will be light brown from now until the day my car meets the grim crusher.
 
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