I need some help with
figuring out my cooling problems.
Just so it doesn’t get
lost in the following BS, I need to state that I think the problem is related to
the coolant pressure. It seems to me to be way too high. I am
beginning to think that the coolant is somehow partially
blocked.
Now the rest of the
story….
After I did the flight
described in the attached email, I installed an opening in the bottom of the
cowl that would work something like a cowl flap that is permanently open.
The new opening is 9 inches by 5 inches or 54 sq in.. There is a flare in
front of the opening that is at an angle of 45 degrees and extends down into the
airstream about 4 inches. (it is 6 inches long.) This opening is in
addition to two 6 X 6 openings, one of which has a 3 inch diameter exhaust pipe
in it.
This helped a little,
but nothing like I expected it would. The pressure inside the radiator
inlet dropped from 10 inches of water to 8 inches of water. (by the way,
Steve was right about it being inches of water and not inches of
Hg.)
The pressure after the
radiator and inside the cowl dropped to 8 inches as well. The temperature
of the water dropped to 208 and the oil a couple of degrees. Neither of
these had the result that I expected.
My water pressure cap
is rated at 21 lbs. I have not calibrated the sender that came with my
EM-2 and it shows 3 lbs when the engine is cold. I assume that this is
zero. When in flight the pressure climbs to 24 lbs and stays there.
I assume that at this point, the cap is at 21 lbs and is bleeding off air.
There is about a pint to a quart of air above the coolant in the bleed
tank.
This morning I ran the
engine on the ground for about 10-15 minutes at an rpm of 3000 to 3200.
The OAT was 75 degrees.
I read the temps and
pressures every minute or two during the run. I hope this doesn’t get
jumbled during transmission.
Oil temp
–
80 103
130
139
144
155
162
165
Air temp after cooler
-
97
109
122
129
133
134
Water temp
-
86 126
161
173
178
190
198
199
Air temp after rad
-
109
133
157
169
179
183
Water pressure
-
2
11
17
20
21
24
I noticed that the
water pressure could be brought from 2 lbs to 9 lbs by changing the rpm while
the engine was still relatively cool
What should I expect
for water pressure at lower temps and how could I go about making a
determination that the water passages are clear?
I am beginning to think
that a rag has been left either in the engine or the radiator. I have
never torn the engine down and I sent the radiator out to have a leak repair a
couple of years ago. It is a double pass radiator. I can look into
the end that has both sides connected thru the radiator cap neck, but not into
the inlet and outlet end.
Suggestions???
Thanks,
Bill
B
From: Bill
Bradburry [mailto:bbradburry@bellsouth.net]
Sent: Sunday, March 20, 2011 5:29
PM
To: 'Rotary motors in aircraft'
Subject: On the subject of
installations...
My water temp has been
running between 199 and 217, depending on the OAT. The oil is pretty
steady at around 175. Today I finally got to fly with pressure probes
inside the cowling. I was all set to try and enlarge the inlet to the
radiator to solve the problem. It turns out that “in” is not the problem,
it is “out” that is the problem!
I have 10 inches of Hg
pressure in the radiator inlet and 10 inches of Hg on the outlet side as well as
the same pressure everywhere I measured inside the cowl. I need to open up
the cowl some so more air can get out. I had considered a cowl flap but
that would not work in this instance because the problem is at cruise. I
need a permanent opening. I am considering louvers and I am looking for a
source. I know some of you are using them. Where did you get them
and how are they installed so that they look ok?
I am also considering
some kind of flare around the exit area to create a low pressure area to help
suck air out. Do any of you have those and do they seem to
work?
While I look into this,
I also need to do something about my muffler…Thank you,
Bobby!
I wonder about that
spiral muffler some of you are trying??
Bill B 9 hours
and counting…
By the way, I was
considering putting a 1 or 2 inch wide piece of cardboard across the bottom of
the oil cooler to partially block it in the hopes that more air would then flow
through the radiator. Sort of like truckers do with the radiator in cold
weather. What opinions do you have about that idea? I realize it
would make more sense if the oil was really cool, but I think the oil might not
get much hotter if an inch or so was blocked. What do you
think???