Date:         Thu, 13 Jan 2005 10:31:21 -0500
Reply-To:     Sam Walters <sam.cooks@VERIZON.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Sam Walters <sam.cooks@VERIZON.NET>
Subject:      Re: subaru head leaks - from subaruvanagon list
Content-Type: text/plain; charset=us-ascii; format=flowed

 From today's postings on the subaruvanagon@yahoogroups list:

I was in unusual situation where I was able to find the head warp "gasket
fail" problem before the dealers were getting any failures. Many years
ago I adapted a new 2.5 (10k miles) to my airplane. I have sensors galore
on the plane, so when the head first started leaking, I was able to look
at the data on my laptop and see that the head leaked pressure to coolant
system 3 seconds after I hit full throttle. It then dissipated 5 seconds
later. I really learned a lot and deliberately operated at full throttle
for long periods (hour or two). All the time logging the pressures and
temps every few milliseconds.

So here's the deal. All failures are caused by air in the cooling system.
No air, no problem. If you have air bubble AND you operate at high
throttle settings, the head will warp. It takes a long time to show up.
So if there was trapped air 6 months ago, then you might now start to see
discolored coolant, overheating. Or it might only occur climbing hill in
hot weather. Only the 2.5 has this marginal condition. All other Subaru's
bullet proof. My flying partner makes a living replacing gaskets on 2.5's
these days. Number one repair item.
It appears that the 2.5 has an area at center of block/head interface
which doesn't have enough coolant flow. When a bubble passes by, it boils
locally. This eventually causes head to warp, gasket to give out. Subaru
has tried 3 different style gaskets, even adding coolant conditioner to
improve heat transfer. Still a problem. But absolutely all failures
caused by trapped air in system. All models of 2.5 liter the same.
The solution is very simple. Just drill and tap your coolant crossover
pipe and add a fitting that allows air to leave engine and rise to your
swirl pot. You will never have a problem. I operate my engine full
throttle for hours at a time. Fabulous engine.


-al wick
alwick@juno.com

Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on engine/airframe from Portland, Oregon
Prop construct, Subaru install, Risk assessment, Glass panel design info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html


--
Sam Walters
Baltimore, MD

89 Syncro GL
85 Westy Weekender

All incoming and outgoing email scanned by
automatically updated copy of Norton AntiVirus.