Where has all my coolant gone?

[redheadmarshal 10]

Started up my VR6 at the weekend for the first time in 2 months - got the low coolant level warning light on the dash. When I checked the expansion tank the level is well below the minimum, but there's no sign of leaks underneath or around the hoses. Any ideas as to how most of the coolant can disappear if it's not leaking? Am off to buya couple of bottles of G12 shortly, but am concerned this may be a symptom of something pricey....

[VW_OwneR_85 1]

just fill it up and run it, must be a small leak, small enough to leak but not drip, water pump, crack pipe,thermostat housing, core plug, theres a few places, have you checked the dipstick for signs of oil/water mix ?

[Jim Bowen 1]

Its G13 now btw

 

I have the same issue with mine atm, just got it back on road and losing coolant, i've checked everywhere and the only bit that i can suspect is the temp sender on the radiator

[OllieVR6 0]

Have a look at this:

 

https://sites.google.com/site/rabitahir/vw-mkiv-vr6-12v-cooling-system

 

Or more specifically, this image (notice the bit missing):

 

https://sites.google.com/site/rabitahir/_/rsrc/1260415685450/IMG_0890s.jpg?height=280

 

I'm in the process of replacing almost the whole cooling system and the only place I found where water could be leaking from are the thermostat housing (mine looked identical to that image above) or the radiator neck (the bit the upper hose connects to). I also couldn't find the leak, I'm 99% certain it was the housing now.

[Stonejag 10]

I replaced my thermostat and 3-part housing with Meyle (OEM) parts from http://www.vwspares.com for under 35 quid last year - all still going strong. Worth it just for peace of mind, VW plastic parts are notorious for being slowly eaten away by the corrosive coolant...

 

Also check the crack pipe - the handbook method of draining the coolant involves twisting the pipe to direct the stream and it tends to crack at one end (next to the water pump) if it's been previously fitted using sealant. Metal replacements are best but if not then treat yourself to a new plastic one for £9! Alternatively it could be a pinhole in a hose (check for steam when engine is warm and it's a cold day out - they may close up when the system's not under pressure) or a duff seal in the expansion tank cap - if so it'll be coming out of the vent in the tank when it gets hot. If you're checking it when stationary, remember the water pump is driven from the aux belt so you'll have more pressure and more chance of finding a leak if someone inside can rev it to 2500ish rpm for you!

 

Stone

[plagued by leaks until he replaced...well, everything :lol:]

[OllieVR6 0]

I never knew you were supposed to rotate the crack pipe....kind of explains why I get coolant everywhere every time I drain the system :lol:

[Stonejag 10]

Don't actually do it! It just knackers it at either end, it's bad enough as stock...

 

To be honest there's no sensible way to do it with the standard setup, the drain hole is so small it comes out in a fan-spray and that smacks straight into the front cross-member so it just goes everywhere. I swapped to a metal crack pipe, chucked the drain plug that was supplied with it and fitted a small brass domestic gas tap in its place - now I can just attach a bit of hose to the tap to drain it where I want it :) You have to be elbow-deep in the bay to reach the crack pipe so anything that helps stop it weeing it all down your arm is worthwhile!

 

You could also try K-Seal - amazing stuff, it sorted tons of my leaks until I could change all the plastic bits. Doesn't clog up your rad or heater matrix but it can even repair the cracks that form around the radiator mounts when your ham-fisted garage hammer rusted mounting brackets into it...

 

Stone