[DaveWWW]

On Sunday my 2006 Jetta TDI dash light that looks like a red thermometer came on as soon as I started the car (cold engine). I stopped it, saw that the coolant reservoir sphere was below minimum so I added enough to bring the sphere to half full. About 15 minutes later the light came on again.

Yesterday it was happening regularly. A half sphere of coolant brings the light on in 15 to 30 minutes.

I'm getting it checked out tomorrow. The strange thing is that I can smell no fluid. There's no steam anywhere. There's no steam coming out the tailpipe. There's no coolant on the driveway. the rad looks dry as far as I can see. There's no smell when I open the hood. After warming up the car I stop and check things while it's idling. Nothing bad that I can see.

I would think that if coolant is getting into the engine I would see steam wouldn't I?

How do I troubleshoot this before I get a heart attack from the mechanic?

Thanks.
David

 

[DAVE PARKER]

Dave
The best way to diagnose this problem (and what your mechanic will do if he is any good) is to use a cooling system pressure tester. This device allows you to pressurize the cooling system without running the car (ie. not getting the motor and the hoses HOT). Once the system is pressurized the mechanic can then start looking for leaks. Leaks could be coming from a coolant hose or a metal pipe or from the heater core. The cooling system pressure testers and the adapters needed to work on most modern cars can get pricey, so not everyone will have one of these.

If there is no sign of leakage from any of these spots then next step is to add a fluorescent dye to the coolant, run the engine and then look for where the dye is showing up with the UV light that the dye reacts to.

Hopefully it is something simple like a pinhole leak from a hose. Sometimes it can get quite time consuming to find a small leak so be prepared for a bill from your mechanic.

good luck.
cheers
dave parker

 

[chittychittybangbang]

Just to add something, autozone rents a coolant tester for free but they don't have the VW adapters. Therefore, you would need the VW adpater to use any generic coolant pressure tester.