Finn Lassen wrote:

Someone told me one can get a chemical kit to test for exhaust

gasses in the

coolant.
I've checked in local stores with no luck. What is it called? And

where can I

get it?

I'm loosing coolant. Tracy and others have suggested that it may be

a failing

combustion chamber/coolant jacket o-ring - the combustion gasses

pressurizing

the coolant.

Before I take the engine apart, I want to be sure that that really

is the case.

Finn

Finn how large is your overflow can? Last time I saw your can (Oct.)

it looked too small.

What happens is the coolant expands when heated and flows out to the

overflow can.

This is normal. If the overflow can is too small some is forced out of
the overflow can each time you fly the airplane. When the engine cools

off

what is in the can is normally sucked back into the engine. If not

enough is in the

can, air will be sucked back into the engine which is a big no no.
I suspect about a gallon can is needed. Make sure the over flow tube

goes

to the bottom of the can.  Try that first.

Paul Lamar

I didn't use to have the problem. I'm now loosing up to 2 quarts per

hour (depending on

power/RPM). Looks like the problem is gradually getting worse.

I replaced the cap and am thinking about going to a higher than 16 psi

cap, but again I

didn't use to loose that much coolant.

So, what is that kit called? What do I ask for?

Finn

Are you sure you are getting all the air out of the engine when you fill
the system. Are you raising the tail when you fill it? Do you have a
vent line from the front (rear in the car) of the engine back to the
pressure cap area?

Well there are some rad pressure check kits. A cold pressure check around
30 psi should show it up real fast. We could not find a kit in Palm

Springs

so I made one for Perry's engine out of a tubeless tire schrader
valve and a pieces of aluminum plate. A lot of external leaks won't
show up on the ground. You need to warm up the engine and have pressure
in the cooling system before they start leaking.

If you can't find any external leaks it could be an O-ring internal leak.
Has the engine been overheated? Could be a broken O-ring land heaven

forbid.

What year is that engine? Also inspect your engine tension bolts to make
sure none are fractured. That is what caused Perry's internal leak.
I'll wager they were never taken out one at a time and coated with
red RTV and replaced. Were they? :-)>

Paul Lamar

I think Finn has tried all the simple stuff.  His problem seems to be a
little stickier.  The system seems to hold static pressure just fine but
starts overflowing at high power settings (but not necessarily overheated).
I guessed that there may be an O-ring leak in the high pressure portion of
the combustion chamber that only leaks at peak combustion chamber pressures.
Just a guess but it fits the symptoms.

Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com

 
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