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Date: Wed, 8 Jun 2005 17:58:19 -0500
Subject: Re: [FlyRotary] Remaining pressure when cold (Re: coolant leak)
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From: Jerry Hey <jerryhey@earthlink.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
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On Wednesday, June 8, 2005, at 04:51 PM, Bill Dube wrote:

>
>>
>> I don't get it.  What is wrong with the cooling system remaining 
>> pressurized?  Mine does and always has.
>
> >>>> You have a copression leak if.... <<<<
>
>         You have a compression leak into the cooling system. Residual 
> pressure is the classic symptom. (The next thing you will see are tiny 
> smoke-filled bubbles in the cooling water.) You are going to have the 
> tear the engine down to fix it.
>
> >>>> Why there is no residual pressure normally <<<<
>
>         The very first time you fill the system, it is possible to 
> have some residual pressure when the system cools down. After that 
> first time, there should never be residual pressure. This is because 
> any vapor you create by heating will condense back to liquid when you 
> cool down again. Actually, the water expands and pushes some air out 
> of the system into the catch tank. When it cools back down, the water 
> contracts and draws a slight vacuum. This will suck water back in from 
> the catch tank.
>
> >>>> Why you might possibly have residual press the first time after 
> you change the coolant <<<
>
>         The first time you heat up the water, you will drive out some 
> dissolved air. After you thermally cycle the water once, this 
> dissolved air is gone. Thus, you may possibly see a tiny pressure 
> remaining the first time, but never again.
>
> >>> Smoke-filled bubbles = compression leak into the cooling system <<<
>
>         If the compression leak is severe, you can sometimes see 
> little smoke-filled bubbles in the coolant. Fill it to the top and 
> don't put the cap back on. Run it at idle and little smoke-filled 
> bubbles may be seen rising to the top. If you see these, you 
> definitely have a compression leak into the cooling jacket.
>
>         You don't always see the smoke-filled bubbles, by the way.
>
>
>         Bill Dube'

Thanks for the clear explanation Bill.  All stuff I did not know but am 
very glad to have learned today.    Jerry
>
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