Low oil pressure reading on gauge--why?

I have a 1991 extra cab pickup with a 22RE engine. It is a 5 speed manual
with about 134k miles on it. I've had no problems with it but now I've
noticed the oil pressure gauge registers a low reading when I'm driving.

The gauge used to hover around the middle range but now hovers around the
"L" end except for brief sweeps into the middle range but then it drops
back
down to the lower "L" side.

My questions are:

1) what can cause this?
2) What troubleshooting steps should I take to determine the cause?
3) Has this happended to anyone else and what did you do to fix it?
4) Could it be a bad sending unit?

I use Castrol 10W30 oil and change it religiously at 3,000 miles and use a
Toyota filter. It drives fine despite the low oil pressure readings but
it
worries me.

Thanks in advance for any advice/tips...


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I don't know if you've had any success figuring this out but I thought
I'd issue a warning.

I have a '94 xtra cab, 22RE engine, 5 spd. manual, 100k miles. For
the last six months / year I've noticed the same oil pressure
behavior that you describe. I knew the oil had been changed at the
appropriate times, and I could tell I had plenty of oil on the
dipstick (and clean oil, too.) I thought maybe it was just a bad
sending unit, something screwy with the electrical, etc.

I also noticed a reduction of power at low rpm/idle. I thought maybe
it was time for a new battery or alternator, or maybe a tune-up.

Then a couple of days ago my timing chain broke while driving home.

I don't think I had any other warning. I certainly didn't hear
anything unusual.

I don't know if the oil pressure reduction might have been related to
the timing chain issue. I've heard that the chain guides can crack and
fall into the pan, screwing up oil distribution. That might explain
the lower oil pressure, I suppose.




On Mon, 18 Jul 2005 18:01:48 -0700, "Yoboslayer" <yobo@@news.com>
wrote:

>I have a 1991 extra cab pickup with a 22RE engine. It is a 5 speed manual
>with about 134k miles on it. I've had no problems with it but now I've
>noticed the oil pressure gauge registers a low reading when I'm driving.
>
>The gauge used to hover around the middle range but now hovers around the
>"L" end except for brief sweeps into the middle range but then it drops
>back
>down to the lower "L" side.
>
>My questions are:
>
>1) what can cause this?
>2) What troubleshooting steps should I take to determine the cause?
>3) Has this happended to anyone else and what did you do to fix it?
>4) Could it be a bad sending unit?
>
>I use Castrol 10W30 oil and change it religiously at 3,000 miles and use a
>Toyota filter. It drives fine despite the low oil pressure readings but
>it
>worries me.
>
>Thanks in advance for any advice/tips...