oil pressure drop
 

2002 S10 4.3 with about 38k on it.
Noticed last night that oil pressure gauge was reading lower than normal.
Midscale is 275 kpa (39 PSI) and it normally runs about there or higher when
hot at highway speed Last night it was down about 1/4 scale at speed which
it normally only would go when at idle stopped. Crawled under and noticed
small amount of oil on the filter but no dripping.
Difficult to check oil level when hot and with flashlight so added about 3/4
quart and restarted. No real change, so left it until morning. Checked oil
level and it was now actually a bit above max on dip stick so wasn't really
short of oil. Started it up and it read 2 bars above midpoint ( there are 4
bars per quarter of gauge range which is pretty normal. Took short drive to
store and back. By the time I was back home the reading had gone low again.
Gauge needle moved more with rev change than last night but still seemed to
go to 1/4 point above idle. Read somewhere that senders can go and oil will
be in plug. Wonder if that might be the source of oil on filter, assuming
sender is near filter base. Is this a common problem on these motors? Could
I be losing pressure hot or maybe sender is now measuring wrong when hot.

oil pressure drop
 

"Ken Hilson" > wrote in message
...
> 2002 S10 4.3 with about 38k on it.
> Noticed last night that oil pressure gauge was reading lower than normal.
> Midscale is 275 kpa (39 PSI) and it normally runs about there or higher
when
> hot at highway speed Last night it was down about 1/4 scale at speed which
> it normally only would go when at idle stopped. Crawled under and noticed
> small amount of oil on the filter but no dripping.
> Difficult to check oil level when hot and with flashlight so added about
3/4
> quart and restarted. No real change, so left it until morning. Checked oil
> level and it was now actually a bit above max on dip stick so wasn't
really
> short of oil. Started it up and it read 2 bars above midpoint ( there are
4
> bars per quarter of gauge range which is pretty normal. Took short drive
to
> store and back. By the time I was back home the reading had gone low
again.
> Gauge needle moved more with rev change than last night but still seemed
to
> go to 1/4 point above idle. Read somewhere that senders can go and oil
will
> be in plug. Wonder if that might be the source of oil on filter, assuming
> sender is near filter base. Is this a common problem on these motors?
Could
> I be losing pressure hot or maybe sender is now measuring wrong when hot.
>
>

Before getting worried put a mechanical oil pressure guage on it
and see what the pressure really is and if it's cause for concern.

Ted

oil pressure drop
 

"Ted Mittelstaedt" > wrote in message
...
>
> "Ken Hilson" > wrote in message
> ...
> > 2002 S10 4.3 with about 38k on it.
> > Noticed last night that oil pressure gauge was reading lower than
normal.
> > Midscale is 275 kpa (39 PSI) and it normally runs about there or higher
> when
> > hot at highway speed Last night it was down about 1/4 scale at speed
which
> > it normally only would go when at idle stopped. Crawled under and
noticed
> > small amount of oil on the filter but no dripping.
> > Difficult to check oil level when hot and with flashlight so added about
> 3/4
> > quart and restarted. No real change, so left it until morning. Checked
oil
> > level and it was now actually a bit above max on dip stick so wasn't
> really
> > short of oil. Started it up and it read 2 bars above midpoint ( there
are
> 4
> > bars per quarter of gauge range which is pretty normal. Took short drive
> to
> > store and back. By the time I was back home the reading had gone low
> again.
> > Gauge needle moved more with rev change than last night but still seemed
> to
> > go to 1/4 point above idle. Read somewhere that senders can go and oil
> will
> > be in plug. Wonder if that might be the source of oil on filter,
assuming
> > sender is near filter base. Is this a common problem on these motors?
> Could
> > I be losing pressure hot or maybe sender is now measuring wrong when
hot.
> >
> >
>
> Before getting worried put a mechanical oil pressure guage on it
> and see what the pressure really is and if it's cause for concern.
>
> Ted
>
>
Thanks, Anyone else with s10 experience? As I don't have a mechanical gauge
I might just change the sender. I do have another electric gauge but don't
know if the sender will fit.

oil pressure drop
 

you are not likely to get a consistent reading when the oil is hot - if
the oil is greatly; above full, or below add.

and it is hard to get a consistent read at hiway speeds - why - if
everything is working? dunno.

at temps above 85°F oil thins very quickly, and cause the oil pressure
to fluctuate. you'd think that there would be a steady oil pressure
reading at this time.

with only a warning light for oil malfunction - it eliminates some of
the oil issues.

and too, not all oil reacts in the same way as far as pressure is
concerned, I find.

"synthetic" is likely to give a more consistent pressure reading.

mho
vfe

oil pressure drop
 

"Ken Hilson" > wrote in message
...
>
> "Ted Mittelstaedt" > wrote in message
> ...
>>
>> "Ken Hilson" > wrote in message
>> ...
>> > 2002 S10 4.3 with about 38k on it.
>> > Noticed last night that oil pressure gauge was reading lower than
> normal.
>> > Midscale is 275 kpa (39 PSI) and it normally runs about there or higher
>> when
>> > hot at highway speed Last night it was down about 1/4 scale at speed
> which
>> > it normally only would go when at idle stopped. Crawled under and
> noticed
>> > small amount of oil on the filter but no dripping.
>> > Difficult to check oil level when hot and with flashlight so added
>> > about
>> 3/4
>> > quart and restarted. No real change, so left it until morning. Checked
> oil
>> > level and it was now actually a bit above max on dip stick so wasn't
>> really
>> > short of oil. Started it up and it read 2 bars above midpoint ( there
> are
>> 4
>> > bars per quarter of gauge range which is pretty normal. Took short
>> > drive
>> to
>> > store and back. By the time I was back home the reading had gone low
>> again.
>> > Gauge needle moved more with rev change than last night but still
>> > seemed
>> to
>> > go to 1/4 point above idle. Read somewhere that senders can go and oil
>> will
>> > be in plug. Wonder if that might be the source of oil on filter,
> assuming
>> > sender is near filter base. Is this a common problem on these motors?
>> Could
>> > I be losing pressure hot or maybe sender is now measuring wrong when
> hot.
>> >
>> >
>>
>> Before getting worried put a mechanical oil pressure guage on it
>> and see what the pressure really is and if it's cause for concern.
>>
>> Ted
>>
>>
> Thanks, Anyone else with s10 experience? As I don't have a mechanical
> gauge
>snip<
Buy one--it is very inexpensive & will last a lifetime & will accurately
answer many otherwise guessed-at answers--including this one. s

oil pressure drop-update
 

"Ken Hilson" > wrote in message
...
While considering options of testing with mechanical gauge, just changing
the sender or maybe even testing with another electric sender/gauge that I
already have I decided to drop the filter a couple times to get rid of the
overfill. I expected to also check the connector on the sender as I thought
it would be attached at the filter adapter.I could not see any sender but
did see 2 pipes from the adapter to my radiator. I did not realize that I
has an oil cooler in the rad. Second and not encouraging was that there
appears to be oil around the middle lower bolt that attaches the tranny to
the aluminum oil pan. Removing filter put oil on the outer bolt but I don't
see how it would wet the centre one, meaning maybe a rear main seal leak.
So question is does the rear seal leaking usually cause a drop in pressure
and where is the oil pressure sender located on the 2002 4.3? Only connector
I can see is on rear left below words "vortec" on the valve cover which has
2 wires. The sender paer says it's 1 blade , so why 2 wires and the pipe
thread looks larger than 1/4 (which I thought I saw somewhere as the fitting
size)
Thanks
> 2002 S10 4.3 with about 38k on it.
> Noticed last night that oil pressure gauge was reading lower than normal.
> Midscale is 275 kpa (39 PSI) and it normally runs about there or higher
when
> hot at highway speed Last night it was down about 1/4 scale at speed which
> it normally only would go when at idle stopped. Crawled under and noticed
> small amount of oil on the filter but no dripping.
> Difficult to check oil level when hot and with flashlight so added about
3/4
> quart and restarted. No real change, so left it until morning. Checked oil
> level and it was now actually a bit above max on dip stick so wasn't
really
> short of oil. Started it up and it read 2 bars above midpoint ( there are
4
> bars per quarter of gauge range which is pretty normal. Took short drive
to
> store and back. By the time I was back home the reading had gone low
again.
> Gauge needle moved more with rev change than last night but still seemed
to
> go to 1/4 point above idle. Read somewhere that senders can go and oil
will
> be in plug. Wonder if that might be the source of oil on filter, assuming
> sender is near filter base. Is this a common problem on these motors?
Could
> I be losing pressure hot or maybe sender is now measuring wrong when hot.
>
>

oil pressure drop-update
 

Ken Hilson wrote:

> So question is does the rear seal leaking usually cause a drop in pressure

No, it will not cause a drop in pressure. The front and rear main seals
on American v8 and v6 engines (and all engines that I know of) are not
exposed to oil gallery pressure, just splash and spray from the front
and rear main bearings. You could remove the seals and run the engine,
and it should have normal oil pressure (at least until all the oil
sprayed out after a while... ;-)

oil pressure drop-update
 

Thanks, that's somewhat good news, I think. Drove it tonight. Get 50-55 psi
cold startup but after 10 minutes and full engine temp I got 35 @2k rpm,
20-25 at 1.5k and 15-20 at idle of 600-700 rpm
"Steve" > wrote in message
...
> Ken Hilson wrote:
>
> > So question is does the rear seal leaking usually cause a drop in
pressure
>
> No, it will not cause a drop in pressure. The front and rear main seals
> on American v8 and v6 engines (and all engines that I know of) are not
> exposed to oil gallery pressure, just splash and spray from the front
> and rear main bearings. You could remove the seals and run the engine,
> and it should have normal oil pressure (at least until all the oil
> sprayed out after a while... ;-)

oil pressure drop-update
 

oil pressure gauges seems to give erratic readings, not that they are in
error, but something causes it - aside from temperature / oil level.

I expect a mid-scale reading at highway speed, and at times in stop and
go city traffic (is there any other kind) it dips - real low.

Why the yo-yo readings?

mho
vfe

oil pressure drop-update
 

Somebody must know where the sensor is located?