Intermittent coolant leak

Steve140

Veteran Member
Joined
Feb 15, 2002
Location
Komoka, Ontario
TDI
2000 & 2011 Golf TDIs
Hi. I have an odd coolant leak on my 2000 Golf (manual transmission). Intermittently it leaks coolant from the drivers side of the head where the coolant flange is. Only does it after it cools down. Leaves a bit of coolant on top of the transmission in the recesses. Hard spot to visually see it. Whenever I put some shop towels to try and catch it it won’t do it. Could it be an O-ring? It’s not any of the hoses as I’ve looked everything over carefully.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
There is a seal between the flange and the head, and another between the flange and the other piece where the coolant glow plugs are. Then the little vent hose around the back side of the vacuum pump.

A pressure tester will narrow it down. All easy to do.
 

TDIGAZ

Veteran Member
Joined
Jan 15, 2008
Location
Eastern Ontario, Canada
TDI
Current: 2003 Jetta GLS Grey 5 spd. Previous: 2003 Jetta GLS Silver 5 spd (lost in a collision)
Hi. I have an odd coolant leak on my 2000 Golf (manual transmission). Intermittently it leaks coolant from the drivers side of the head where the coolant flange is. Only does it after it cools down. Leaves a bit of coolant on top of the transmission in the recesses. Hard spot to visually see it. Whenever I put some shop towels to try and catch it it won’t do it. Could it be an O-ring? It’s not any of the hoses as I’ve looked everything over carefully.
I have almost exactly the same thing…
It leaks only a few drops and only intermittently, but I think I have it narrowed it down to the o-ring between the coolant flange and the head.
I have new o-ring ready to go, but my plan is to monitor the coolant level through the winter and hopefully push off the repair until the weather warms up.
 

Genesis

Top Post Dawg
Joined
Feb 26, 2003
Location
Sevier County TN
TDI
'03 Jetta Wagon
The splitter pipe (plastic) at the top, which is right there, can fracture INSIDE the small hose. It looks perfectly fine but does leak a bit.... right up until it comes apart on you when the broken piece backs out! Its cheap to replace and believe it or not the local Chineesium places (e.g. Autozone) probably have it, fortunately.
 

Steve140

Veteran Member
Joined
Feb 15, 2002
Location
Komoka, Ontario
TDI
2000 & 2011 Golf TDIs
Update: Changed the coolant flange o-ring and the temp sensor o-ring while I was at it. $5 in parts and not difficult except the steel “Jesus” pipe as I call it blocks the removal of the flange housing. We gently bent it back 1/2” since i didn’t want to attempt to remove that and so far no leaks. The coolant flange o-ring came out in 2 pieces so it was definitely the culprit.
 
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