Internal leak would be into the crankcase, and you'd know about that!  Blown internal head gasket ring would over-pressurize the system and coolant would come out of the overflow bottle.  Keep looking, the front heater valve above the spare or a cracked expansion tank can leak under pressure and you don't always see it.

Since you have metal coolant tubes to the radiator, I doubt those are leaking like the plastic tubes do, but I'd make sure all connections are tight. Last, it could be the outer rubber head gaskets with a slow leak. :-(  

Stuart 

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of David
Sent: Wednesday, March 30, 2016 7:02 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Coolant Loss- is it that time again?

On my 85 1.9 (second set of heads...that we did 11 years ago) I'm suspecting internal leakage...

I have had a lot of coolant loss over a long period of time...I topped up the bottle- thinkng that maybe when a heater control switch was switched out that we just didn't get all the air out of the system...

I did have another external leak that I fixed- but something just doesn't seem right.

Just finished pouring about a gallon of antifreeze into the system this AM- and doing some bleeding...what's next? How can I locate this internal leak?
Or would there be some other not so obvious places? Rear heater is bypassed...maybe lost coolant from that operation and it's only showing up now...something aint right!

The engine runs like a champ- full power - after my more recent electrical (I believe to have been) issues- reseating all major suspects...it runs and idles wonderfully....

Any advice is welcome... do we have to check for exhaust in the coolant?

Dave
85 1.9 GL MT