My bet ... both from experience and logic ... is that you either have a
cracked head or a metal head gasket (or gaskets) that isn't/aren't sealing.

The pressure test that it passes is nowhere near the pressure of
combustion when the engine is running.

Mike

John Runberg wrote:
> Slowly have been playing w/ a 90 GL that's had a shload of issues. We're down to "hobby" status on this one as no-one in their right mind would keep fixing things :)
>
> Back-story:
> Have replaces a series of failed parts located by observation (coolant leaking, etc...) - radiator, some hoses new and some reattached, main coolant and overflow tanks + sensor.
>
> Situation:
> Consistently have been getting air into a properly bled system (by list procedure, Bently, two separate specialty shops). Has had pressure test done & system holds pressure with no leaks visible - HOWEVER smell says there *might* be a small leak @ rear heater core (have not dug in quite yet). Amount of air can be several seconds when front bleeder is opened after a 10m drive.
>
> Latest:
> Noticed steady stream of air bubbles in overflow tank (behind license plate) yesterday. At idle, 2-3 bubbles per second. This is on a (nasty engine rebuilder) engine installed by PPO perhaps 30k ago.
>
> Opinions?
>
> As mentioned, we're into hobby status here. $$$ will be spent first restoring the Westy, but hate to drop the investment in this bottomless pit :) so keep pluggin on. Heads? Reseal or replace? Pull 'em and find out? Have talked to Hans and Karl about engine conversions, but just want to locate this prob first.
>
> thanks,
>
> john
>