01M tranny

MartyK

Member
Joined
Sep 21, 2016
Location
Montreal, Canada
TDI
2003
Hello everyone.

The cooler on top of my 01M transmission is slowly leaking antifreeze, but I can't find WHAT is leaking. All hoses and clamps are good; the cooler (removed) has no visible damage or cracks.
Anybody have any ideas?
Thanks
 

Gippeto

Active member
Joined
Jan 25, 2018
Location
Alberta Canada
TDI
2003 Jetta sedan
Plug both pipes, pressurize it (15psi MAX) and submerge it in a bucket of water. (or spray it with soapy water...)

Hose clamps and a bicycle inner tube provide the means to plug off the pipes...

Safe to assume you checked the coolant flange...mine was leaking there.

Al
 
Last edited:

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
NOTHING to do with a 01M Transmission.
Retitle to:
Coolant leak, cant find it over the trans area.

No need to pressurize it at all that way, do yourself one step better.
Drain the coolant by sucking it up into a CLEAN wet mode shopvac
Now fill with water and a about 1/4 cup of dish soap or laundry detergent, start the car up for about 1 minute or less, drain the water and soap to the ground. Now rig up a fitting and pressurize it int he car to 15psi and watch for bubbles that will form from the inside out.

Or you could just clean the car really well, get the UV die and put a few drops in the system and check with a black light for where its coming out.
 

Gippeto

Active member
Joined
Jan 25, 2018
Location
Alberta Canada
TDI
2003 Jetta sedan
Thermostat housing is on the "side" of the engine block...toward the front of the car as it's transverse mounted. The coolant flange "looks" like it should be a thermostat housing...but isn't. It's on the "rear" of the block/bell housing end/drivers side....pretty much above the trans cooler/heater.

My terminology might be a little off...this is the first vehicle I've had with a transverse mounted engine.

The coolant flange looks like this;

https://www.google.ca/search?q=tdi+...SOs-XZAhUES2MKHTVkB-0QsAQIKA&biw=1366&bih=637

Thermostat housing looks like this;

https://www.idparts.com/thermostat-housingcoolant-flange-a4-alh-p-653.html

I read they were often brittle and broke during removal, so I got both at NAPA along with a new thermostat...would change them all while the coolant is drained...and then replace the coolant if it's due, nearly due...or contaminated.

In my case, both housings were perfectly usable, and would have just needed new orings. Swapped them out anyways.

Al
 

MartyK

Member
Joined
Sep 21, 2016
Location
Montreal, Canada
TDI
2003
FOLLOW-UP
New cooler is installed and the leak is gone, but I still can't figure out WHERE the old cooler was leaking. (Maybe a fine crack which would only be visible under pressure.)

Again thanks.
 
Top