Date: Sun, 16 Sep 2007 09:58:57 -0700
Reply-To: Alistair Bell <albell@UVIC.CA>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Alistair Bell <albell@UVIC.CA>
Subject: Re: Testing pressure cap
In-Reply-To: <d81c42190709160942w20694905qf18d2b9f7cdba905@mail.gmail.com>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed
Ah,
I understand now :)
wondering if the fluid gets sucked back in from overflow, I get it.
I have diesel set up, had to replace cap a few years ago, (mechanic
friend got a BMW cap as replacement). I too was concerned that the
fluid was not coming back into the system. The old cap's gasket
appeared worn, cracked.
I don't think its a valve per se, I think its the rubber gasket that
makes the "check valve".
Alistair
On 16-Sep-07, at 9:42 AM, John Meeks wrote:
Thanks Alastair and Larry~
The Bentley tester will tell you if the pressure relief valve is
working but not if the vacuum valve, which would take up coolant from
the overflow tank, is working.
I'll set up something with an old expansion tank so I can apply both
pressure and vacuum to the cap.
The illustration in Bentley shows a diesel cap on the end of the
tester but I'll assume the relief pressures are the same. I'll let
you know what I rig up and the results.
Thanks for the help.
John
On 9/16/07, Larry Alofs <lalofs@gmail.com> wrote:
> Hi John,
> The Bentley gives the same specs and procedure for the early and
> late MY
> caps even tho they don't look the same according to the illustrations.
> Assuming you don't have the Stant tester shown on page 19.18,
> you need an
> extra expansion tank or the equivalent or perhaps you could do it
> right on
> the van if you can find another practical place to pressurize the
> system.
> Of course you need a pressure gauge and some way to attach it.
> The cap should allow pressure to escape when it gets into the
> range of
> 13-17 psi and should let coolant back into the tank when there is a
> partial
> vacuum of 0.3-1.45 psi. Instead of vacuum from the tank side, you
> could
> apply pressure to the overflow tube.
> You did save that old cracked expansion tank, didn't you? :-)
>
> Larry A.
>
>
>
>
> On 9/16/07, John Meeks < vanagon@gmail.com> wrote:
>> Hi List,
>>
>> Is there a method for testing the coolant expansion tank pressure
>> cap?
>>
>> we just drove Byron (85 GL) back up from his front hose breakdown
>> (250
>> mi), and the shop that replaced the hoses filled her up with some
>> kind
>> of stop leak and the cap is all gunked up.
>>
>> I'm wondering if a cap failure may have contributed to the hose blow
>> but can't find any way to test the cap in the archives.
>> --
>> John Meeks
>>
>> Vanagon Rescue Squad
>> http://www.vanagonauts.com/Vanagon_Rescue_Squad74.htm
>>
>> '91 Multivan, '85 GL
>> Northern Michigan
>> KC8ZFN
>>
>
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