The forward pport tube is leaking steadily unfortunately.  There is no
indication of leakage inside the engine (no white smoke to be seen & no
fluid ejected while hand propping) but the fluid level leading to the water
pump is dropping steadily.  Looks like the fluid gets cooked off as it
leaks
while the engine is running (thus no puddles or drips while running).
 Fluid
puddles on the top of the exhaust flange after running, indicating it leaks
even with no water pressure.

Absent the pport leak, we'd be gearing up for first flight.

Mark (Rocky Mtn High)


You will need a few things to fix the leak.
A vacuum pump,
a vacuum gage (McMaster Carr part #3935K52 For $12.30)
and some pro seal from Aircraft Spruce.

Drain the coolant.

Remove the water pump and make a plate to block
off the water pump connection to the block.
Install a fitting in the block off plate for the vacuum pump.
Install another 1/8 inch pipe fitting in the plate for a vacuum gage.
Seal all other openings to the water jacket such as the coolant
drain and the heater connection. Start the vacuum pump
and suck in some alcohol where the leak is to clean
out the passage. You should be able to hear air going
through the leak using a small hose stuck in your ear.

Keep the pump going and keep feeding in
small quantities of alcohol. The air flowing in the leak will
dry the alcohol. Stop feeding in alcohol and feed in a tiny bit of ProSeal.

Aircraft Spruce has a 2 oz kit for $17. Buy it from AC spruce to be sure
your getting the right tank sealing stuff.
http://www.aircraftspruce.com/catalog/cspages/proseal.php

BTW There seems to be a lot of confusion out
there about Pro-Seal. It appears several companies are using the name.
I think this is the right company. It is used to seal fuel
tanks and it stays flexible.
http://www.bergdahl.com/PRC_ByTheNumber.htm

Listen to the leak and check the vacuum gage. The vacuum reading
should increase. (Higher vacuum, lower absolute pressure)
Shut off the pump and wait 24 hours. Turn on
the pump and check for the leak again. Listen with a tube stuck in
your ear. If it is still leaking repeat another application of a tiny
amount of Pro seal with the pump going.  When it appears to be sealed.
Remove the vac gage and pressurize the block to 50 psi using a tubeless
tire
valve mounted in the water pump block off plate and see if it
holds the pressure over night.

Vacuum pumps can be borrowed or rented from HVAC shops. They all have
them. They are used to dehydrate AC systems.
http://www.robinair.com/acsolutions/acvacuum/acvacuum.php
http://www.climatedoctors.com/items/item.aspx?itemid=429924

-----------------------------------------

Harbor Freight has a low cost vacuum pump powered off an air compressor.
I have seen these things used to make vacuum bag composite layups.

These are cheap and they work but maybe not as well as a a Robinair
powered by a 110 Volt 1/4 HP motor. Worth a try.


Paul Lamar

I got one of the air-powered Harbor Freight vacuum pumps.  I can't comment
on performance at sea level, but up here in the thin air, the unit can't
begin to draw the kind of vacuum the literature claims.  They quote 28.5" hg
on 4.2 CFM at 90psi.  Running higher pressure and more CFM, the unit drew a
max of 20" hg up here.  At 90psi and 4.5CFM constant (what my compressor can
put out) the unit was drawing around 14" hg.  And this was just connecting
the input straight to a vacuum gauge, much less a volume of air you wanted
to pump down.  BTW -- it was noisy as hell with all that air being vented
through the unit.

Anyway -- not a viable solution up here.  Maybe a better performed down in
the "fat air" where most folks live.

Mark  (Rocky Mtn High)