No! No! Rattling is GOOD!

[Mike Arman <armanmik@n-jcenter.com>]

>
>Date: Tue, 6 Oct 1998 10:34:32 -0700 (PDT)
>From: Orin Eman <orin@wolfenet.com>
>Subject: Re: 5k A/C programmer debugging
>
>> 1) One of the vacuum solenoids (the footwell one) won't hold vacuum on
>> the vacuum side, but the others do. They are supposed to hold vacuum,
>> without any voltage applied, right? But holding vacuum can also indicate
>> that the solenoid is swollen shut, I understand, so I'm not sure how to
>> diagnose it. The whole programmer does rattle, but it's hard to tell if
>> I'm hearing two or three or four rattles.
>
>None of mine hold vacuum with no power.  Rattling implies that they
>probably wouldn't hold a vacuum without power.
>

No! No! You WANT them to rattle! When the rubber diaphragm swells up, then
the solenoid doesn't rattle! (the valve is swollen shut) The shake and
rattle test is a power-off test. If they all rattle, then, if you want to,
try to see which ones hold vacuum. IME, if the solenoid rattles, its OK,
look elsewhere for the problem. I've fixed some of these simply by
soldering in rattling solenoids to replace the quiet ones - the controller
box then works just fine. You may be over-diagnosing this. Go for the
simpler fix - no rattle, no good.


>BTW, IF there is oil getting in there, then I'd suspect the main
>check valve.  Air flow is towards the engine.  Only under boost
>could air flow from the engine towards the solenoids and there is
>a check valve that's supposed to stop that happening.

Oil gets in on NA engines, too. (Ask me how I know.) What's needed is a
TRAP, just a small fuel filter in the vacuum line (black hose, I think, but
not sure.)

Best Regards,

Mike Arman