From: "William Schertz wschertz343@gmail.com" <flyrotary@lancaironline.net>
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Date: Thu, 26 Nov 2020 11:42:02 -0700
Message-ID: <CAOgm+a4Src1nB0r=mg+A=1VhzEW6qYpAc+jAtVokFe34k2DhLA@mail.gmail.com>
Subject: Re: [FlyRotary] My RV-3B 13B cooling problem -- engine rebuild time?
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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You are a tail dragger, so in flight, if there were air/gas in the system
the temp probe might not be in contact with the fluid. when you land, fluid
flows back to sensor which then shows 185


On Thu, Nov 26, 2020 at 8:07 AM Finn Lassen finn.lassen@verizon.net <
flyrotary@lancaironline.net> wrote:

> Over the last few years I've noticed more and more coolant (Evans) in
> the overflow tank.
>
> This is an open non-pressurized system -- a header tank on top of the
> firewall -- bottom outlet goes to the pump inlet, and near top to the
> thermostat (cap) filler neck.
>
> I though the problem was that there was a small leak in the system
> somewhere so coolant was not being sucked back into the header tank and
> engine as the engine cooled down.
>
> Now I'm beginning to think that it could be blown (or weak) o-rings
> allowing compression/exhaust gasses to escape into the cooling passages,
> forcing out the coolant.
>
> In a normal pressurized system, one should be able to look at the
> coolant pressure gauge (I don't have that -- no sensor) and see pressure
> increase as RPM is increased if there were blowby, I guess.
>
> But how do I do it in a non-pressurized system? Add a pressure gauge and
> temporarily block the hose to the overflow tank and run the engine for a
> few seconds?
>
> I'd rather not do an engine rebuild if I don't have to. Any other ideas
> (than coolant o-ring) of what could cause coolant to accumulate in the
> overflow tank?
>
> One more data point: on flight before last the water temp (sensor
> mounted near top of pump housing -- filler neck) dropped to 60F (same as
> with disconnected sensor), went back to land, and during and after
> landing temp showed 185F. I figured it must have been a bad connector,
> but was worried about lost coolant. Later I pulled the cowling and found
> about 1/3 more in overflow tank that what I'd seen last time the cowling
> was off.
>
> Finn
>
>
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<div dir=3D"ltr">You are a tail dragger, so in flight, if there were air/ga=
s in the system the temp probe might not be in contact with the fluid. when=
 you land, fluid flows back to sensor which then shows 185<div><br></div></=
div><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr">On=
 Thu, Nov 26, 2020 at 8:07 AM Finn Lassen <a href=3D"mailto:finn.lassen@ver=
izon.net">finn.lassen@verizon.net</a> &lt;<a href=3D"mailto:flyrotary@lanca=
ironline.net">flyrotary@lancaironline.net</a>&gt; wrote:<br></div><blockquo=
te class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px =
solid rgb(204,204,204);padding-left:1ex">Over the last few years I&#39;ve n=
oticed more and more coolant (Evans) in <br>
the overflow tank.<br>
<br>
This is an open non-pressurized system -- a header tank on top of the <br>
firewall -- bottom outlet goes to the pump inlet, and near top to the <br>
thermostat (cap) filler neck.<br>
<br>
I though the problem was that there was a small leak in the system <br>
somewhere so coolant was not being sucked back into the header tank and <br=
>
engine as the engine cooled down.<br>
<br>
Now I&#39;m beginning to think that it could be blown (or weak) o-rings <br=
>
allowing compression/exhaust gasses to escape into the cooling passages, <b=
r>
forcing out the coolant.<br>
<br>
In a normal pressurized system, one should be able to look at the <br>
coolant pressure gauge (I don&#39;t have that -- no sensor) and see pressur=
e <br>
increase as RPM is increased if there were blowby, I guess.<br>
<br>
But how do I do it in a non-pressurized system? Add a pressure gauge and <b=
r>
temporarily block the hose to the overflow tank and run the engine for a <b=
r>
few seconds?<br>
<br>
I&#39;d rather not do an engine rebuild if I don&#39;t have to. Any other i=
deas <br>
(than coolant o-ring) of what could cause coolant to accumulate in the <br>
overflow tank?<br>
<br>
One more data point: on flight before last the water temp (sensor <br>
mounted near top of pump housing -- filler neck) dropped to 60F (same as <b=
r>
with disconnected sensor), went back to land, and during and after <br>
landing temp showed 185F. I figured it must have been a bad connector, <br>
but was worried about lost coolant. Later I pulled the cowling and found <b=
r>
about 1/3 more in overflow tank that what I&#39;d seen last time the cowlin=
g <br>
was off.<br>
<br>
Finn<br>
<br>
<br>
---<br>
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</blockquote></div>

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