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Tue Apr 22, 2014 7:42 am

Very recently, was driving along fat, dumb and happy, when... the red blinky light came on. Temp was still in the normal range, where it usually sits, just on top of the little red light.
Pull off, open up, and the pressure reservior is about half empty, and the overflow tank is bone dry. No sign whatsoever of leak - nothing in the engine bay, no smell, nothing under the bus, nothing under the radiator. So, I fill the pressure tank, re-fill the overflow and start up. Everything normal. I stand there watching the engine bay - and a 'bubble', just one, enters the pressure tank and the level drops to about 2/3 full. Temp still normal, red blinky light not on. I let it run for about 20 minutes, and it stays that way, steady state, no change. I drive home, about 15 minutes. Everything normal - except just about 1 mile from home the temperature begins to rise. When I get home the temp is about 2/3 way up the gauge, still no light, no fan. I force the fan on with the A/C control, no change. Got home, shut down - took a look. Still nothing - no visible leak, no smell. While running, did not see any flow of bubbles into the pressure tank except for the one after the refill.
Does this forebode a possible head gasket issue? Other thoughts? It's got to be going somewhere, right?!

Tue Apr 22, 2014 7:54 am

When cool, fill the expansion tank to the top and overflow tank to the MAX mark and monitor.

Could have easily been an air pocket that finally was purged.

Tue Apr 22, 2014 7:59 am

insyncro wrote: When cool, fill the expansion tank to the top and overflow tank to the MAX mark and monitor.

Could have easily been an air pocket that finally was purged.

I changed the radiator last spring, it's been AOK since then - about a year. Seems any air still left in the system should have purged long ago, no?

Tue Apr 22, 2014 8:12 am

The cooling system is designed to ebb and flow every single time it reaches operating temp and than cools down.
Air can easily get into the system if the overflow tank is low and the system calls for more fluid as it cools.

Tue Apr 22, 2014 8:41 am

insyncro wrote: The cooling system is designed to ebb and flow every single time it reaches operating temp and than cools down.
Air can easily get into the system if the overflow tank is low and the system calls for more fluid as it cools.

Point well taken. Will do as you suggest from cold start and monitor. But - Am diligent about, and check the overflow tank regularly, and it's always been consitantly at the full mark since the radiator change and bleed, so am afraid 'something' has changed in the system.

Tue Apr 22, 2014 8:55 am

If you feel it is combustion gases getting into the system, do a leakdown test and you will know exactly how much and which cylinders :wink:

Tue Apr 22, 2014 9:03 am

I had a similar issue this past year. It turned out that my heater valve above my spare tire carrier out of my heater core had a slow leak. The antifreeze never dripped on the ground. Just a steady stream down the radiator line and dried on the spare tire.

I second the air pocket also. I pressurized my system...bled...pressurized...bled and still had air pockets clear for a month. Once you get air in the system in the rear heater and heater core, it is hard to get it out when you only bleed through the radiator.

I am contemplating pulling my rear heater. I hear horror stories of them leaking and ruining your floor and carpet. You may not notice it for a long time unless you pull the cover and inspect.

Just thinking of the hard to see places you may have a slow leak and don't realize it. Food for thought.

Tue Apr 22, 2014 9:39 am

AKWesty wrote: I had a similar issue this past year. It turned out that my heater valve above my spare tire carrier out of my heater core had a slow leak. The antifreeze never dripped on the ground. Just a steady stream down the radiator line and dried on the spare tire.

I second the air pocket also. I pressurized my system...bled...pressurized...bled and still had air pockets clear for a month. Once you get air in the system in the rear heater and heater core, it is hard to get it out when you only bleed through the radiator.

I am contemplating pulling my rear heater. I hear horror stories of them leaking and ruining your floor and carpet. You may not notice it for a long time unless you pull the cover and inspect.

Just thinking of the hard to see places you may have a slow leak and don't realize it. Food for thought.

Appreciate the comments. Rear heater has been removed and the tubes were connected together. I did check them, they are dry and in good shape. But I definitelly will drop the spare and check the heater core valve up in there!

Tue Apr 22, 2014 9:44 am

The heater circuits have weak points for sure.
While pressure testing, I manually flex connections by hand.
Loose or weeping ones will present themselves.

Tue Apr 22, 2014 10:43 am

Any cracks in the bottle near the top it will only leak when it gets hot.

Wed Apr 23, 2014 1:33 pm

Well, bad news. Took it to my good friend and experts at Complete Auto in Staunton, VA - Paul and Keith are Westy/Vanagon gurus. When I could find nothing obvious, they did a complete cooling system checkout, and alas it is the dreaded head/head gaskets. Guess I am not surprised - original engine with 150K+ on the clock... it's time. And, it's in good and trusted hands.