84 4k oil pressure light

[urq]

While I'm as much a fan of "while you're in there" as anyone ... I'm not so
sure it is necessary here.  I can't say that I've ever heard of a LP switch
failing ... although I have replaced one for weeping oil.  The low pressure
switch will take just about any pressure in the system at all as acceptable
... I view it as a gross failure detector (IOW you've got a major problem).
That is the reason the second switch was added ... and as long as the high
pressure switch's warning is working you're pretty well covered.  

There's one more quite common culprit for spurious oil pressure warnings on
the cars from this vintage, and it is the electronic module that disables
the warning when the engine RPM is below a threshold.  As components age the
error check can come on at a lower RPM than originally intended.  In this
scenario you would get a warning at below 2k RPM that would go away once the
revs were up above say 2.2k RPM.  If you see this sort of behavior and
replace the high pressure switch you will find that the "problem" remains
... it is due to the electronic module.  

If you really want to minimize soiling your shorts get an oil pressure
sender and put a gauge in the car.  I usually leave the pressure switches to
provide an alert ... but when you hear the warning chime you can look at the
oil pressure to see how bad things are ... 

Steve B
San Jose, CA (USA)

-----Original Message-----

While you are there, do them both. Crazy not to. Actually they are so 
inexpensive I can't understand not doing them every couple of years. Saves 
your underwear!

----- Original Message ----- 

> I've had the same problem with two 1.8 4000's years ago. In both
> cases, the 1.8 bar sender was going bad. Also, in both cases, it was
> somewhat intermittent, although the '85 kept getting more frequently
> until I replaced the switch.
>
> Tony
>
> On Thu, Dec 11, 2008 at 8:02 PM, Bares, Vittorio
> <Vittorio.Bares at nuance.com> wrote:
>> That's good advice.
>>
>> Interestingly enough, I took it out again today, this time, no issues,
>> no oil light.
>>
>> Its been sitting a long time, there must be some level of corrosion on
>> all the electricals as the more I drive it, the more stuff, just kinda -
>> wakes up.
>>
>> For instance, when I first took it down the road, neither left or right
>> blinker worked. Then, after a few attempts, the left blinker started
>> working, but not the right. After a few more tries, they both worked,
>> but the right blinker had a fast blink, indicating a bulb or something.
>> A few more miles, now they both work perfectly.
>>
>> I'll change out the switches anyway - oil pressure is not something I'd
>> like to trifle with, esp since they are cheap replacement parts.
>>
>> Thanks all...
>>
>> Vittorio -