Mystery coolant leak

3turboz

Veteran Member
Joined
Jul 29, 2011
Location
Tempe AZ USA
TDI
2000 Golf GL Wolfsberg
Hi Gang,

My 2000 ALH Golf has a coolant drip and I just can't see where it is coming from. Seems to only drip when cold, and very slow but steady drip. Took about a month to get the low coolant warning to come on.

Seems to be coming from somewhere under the injection pump and the drops run down the front of the oil pan on the right side. I did do a TB and water pump about 20k miles ago.

If this sounds familiar to anyone, please share your experiences.

Thanks!
 

LNXGUY

Top Post Dawg
Joined
Jan 10, 2004
Location
Barrie, Ont, Canada
TDI
'05 Jetta TDI Wagon
Have you looked to see if the waterpump is weeping? There are no coolant lines under the injection pump, closest thing would be the lines running to the oil cooler.
 

RacerTodd

Veteran Member
Joined
Jun 28, 2007
Location
Kirkland, WA
TDI
2001 Golf TDI
The thermostat is directly under the injection pump. Look below the pump and above the alternator. You'll see the black plastic thermostat housing sticking out of the block with a coolant hose attached to it. Leaks from the housing are not uncommon.
I prefer to use a VW thermostat as they clip onto the housing, which makes installation much easier. Get a new housing as you'll break off the tabs when you remove it - they're super cheap.
Aftermarket thermostats don't clip into the housing. Harder to install but cheaper than the VW unit.
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
The thermostat is mounted to the block behind the injection pump. Common leak point. Get a thermostat, seal and housing since you will probably break the tabs for the thermostat.
 

3turboz

Veteran Member
Joined
Jul 29, 2011
Location
Tempe AZ USA
TDI
2000 Golf GL Wolfsberg
Thermostat and housing were replaced at the TB service with the water pump. I can see the t-stat well has no coolant in it.

Looks just like the symptoms of the link posted by TDITALIAN, so looks like I need to dig till I can get to that O-ring on the pipe.

And yes, this forum and the community is AWESOME. Thanks!
 

TDITALIAN

Active member
Joined
Nov 7, 2004
Location
Los Angeles, CA
TDI
2003 Jetta Wagon, Slv, 5 spd 1999.5 Silver Jetta Sedan 5spd
I used a light coating of Elring sealent on the o ring and it's held up fine for the past few years. Good luck with it!
 

vwdieseling

Veteran Member
Joined
Apr 5, 2012
Location
Lima Ohio
TDI
Beetle, more bugs
On the 1.9 ALH there is a metal coolant line directly behind the pump. There is a hose attached.
 

3turboz

Veteran Member
Joined
Jul 29, 2011
Location
Tempe AZ USA
TDI
2000 Golf GL Wolfsberg
Thanks for the advice. Pretty sure the pipe was leaking at the oring as in post #8 (what a PITA that is!)

However, it looks like the thermostat was also leaking. I kind of dismissed that since the thermostat, housing, and seal were only a year old. Another member told me he had the same issue and always uses silicone on the thermostat seal.

Drip free for now!
 
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