Funny Oil Pressure gauge question...

Hi,

A general question about my grandfather 86 Dodge Caravan...

When you first start it up the Oil Pressure Guage (its a basic analog dial
like the speedometer, engine temp and such) goes up to 3/4 mark between High
and Low pressure.

After driving it for 5 miles or so, it slowly floats down to half way
between High and Low pressure.

After that if the speed drops below 20 or 30mph it settles down to 1/4
between High and Low pressure. It tends to stay there as long as the speed
stays below 30 (I notice it when I'm stuck behind a snowplow for a long
distance) but it goes back up to half way once I get back up to 50mph+

I check the oil levels every so often just to make sure and it hasn't moved
nor are there any leaks. Am I worrying for nothing or should get a mechanic
to check it out?

Its fine other than this, and everything else runs and drives nicely. Is it
something to worry about or should the pressure guage move like this in all
vans?

thanks for any advice!

"slipandfall" > wrote in message
...
> Hi,
>
> A general question about my grandfather 86 Dodge Caravan...
>
> When you first start it up the Oil Pressure Guage (its a basic analog dial
> like the speedometer, engine temp and such) goes up to 3/4 mark between
> High and Low pressure.
>
> After driving it for 5 miles or so, it slowly floats down to half way
> between High and Low pressure.
>
> After that if the speed drops below 20 or 30mph it settles down to 1/4
> between High and Low pressure. It tends to stay there as long as the speed
> stays below 30 (I notice it when I'm stuck behind a snowplow for a long
> distance) but it goes back up to half way once I get back up to 50mph+
>
> I check the oil levels every so often just to make sure and it hasn't
> moved nor are there any leaks. Am I worrying for nothing or should get a
> mechanic to check it out?
>
> Its fine other than this, and everything else runs and drives nicely. Is
> it something to worry about or should the pressure guage move like this in
> all vans?
>
> thanks for any advice!

1986. How many miles?

Two dynamics are happening he As the oil heats up it flows through the
system better, even though it is (hopefully...) a multigrade and your
Grandpa doesn't use straight 30 weight, the guage will go a little lower.

The other is that things are wearing out in the bottom end of the engine,
and 'allowing' oil to flow in more passages than the original manufacturing
called for. Things to look for are piston bearings and rods, rings (esp if
it 'puffs' when started) and a weak oil pump.

I mostly drive Toyotas. I have driven a Corolla like this for about 8 years.
Just keep changing the oil regularly. I don't think an '86 is worth a
$6-1200 rebuild, unless the rest of the thing is in exceptional condition.

Oops, I meant to say 1996 about 110k. Sorry if this confuses the issue. Same
advice?


"Hachiroku" > wrote in message
news:HG6Ef.3901$UY3.2887@trndny05...
>
> "slipandfall" > wrote in message
> ...
>> Hi,
>>
>> A general question about my grandfather 86 Dodge Caravan...
>>
>> When you first start it up the Oil Pressure Guage (its a basic analog
>> dial like the speedometer, engine temp and such) goes up to 3/4 mark
>> between High and Low pressure.
>>
>> After driving it for 5 miles or so, it slowly floats down to half way
>> between High and Low pressure.
>>
>> After that if the speed drops below 20 or 30mph it settles down to 1/4
>> between High and Low pressure. It tends to stay there as long as the
>> speed stays below 30 (I notice it when I'm stuck behind a snowplow for a
>> long distance) but it goes back up to half way once I get back up to
>> 50mph+
>>
>> I check the oil levels every so often just to make sure and it hasn't
>> moved nor are there any leaks. Am I worrying for nothing or should get a
>> mechanic to check it out?
>>
>> Its fine other than this, and everything else runs and drives nicely. Is
>> it something to worry about or should the pressure guage move like this
>> in all vans?
>>
>> thanks for any advice!
>
> 1986. How many miles?
>
> Two dynamics are happening he As the oil heats up it flows through the
> system better, even though it is (hopefully...) a multigrade and your
> Grandpa doesn't use straight 30 weight, the guage will go a little lower.
>
> The other is that things are wearing out in the bottom end of the engine,
> and 'allowing' oil to flow in more passages than the original
> manufacturing called for. Things to look for are piston bearings and rods,
> rings (esp if it 'puffs' when started) and a weak oil pump.
>
> I mostly drive Toyotas. I have driven a Corolla like this for about 8
> years. Just keep changing the oil regularly. I don't think an '86 is worth
> a $6-1200 rebuild, unless the rest of the thing is in exceptional
> condition.
>

"slipandfall" > wrote in message
...
> Oops, I meant to say 1996 about 110k. Sorry if this confuses the issue.
> Same advice?

Pretty much!

I had a '92 FWD G'Vger with 229,000 miles on it, and the OP guage was steady
as a rock!
I have a '92 AWD G V'ger right now with 125,000, and the OP guage bottoms
out (and I MEAN bottoms out) at lights and stop signs. You never know what
an engine will take...

>
>
> "Hachiroku" > wrote in message
> news:HG6Ef.3901$UY3.2887@trndny05...
>>
>> "slipandfall" > wrote in message
>> ...
>>> Hi,
>>>
>>> A general question about my grandfather 86 Dodge Caravan...
>>>
>>> When you first start it up the Oil Pressure Guage (its a basic analog
>>> dial like the speedometer, engine temp and such) goes up to 3/4 mark
>>> between High and Low pressure.
>>>
>>> After driving it for 5 miles or so, it slowly floats down to half way
>>> between High and Low pressure.
>>>
>>> After that if the speed drops below 20 or 30mph it settles down to 1/4
>>> between High and Low pressure. It tends to stay there as long as the
>>> speed stays below 30 (I notice it when I'm stuck behind a snowplow for a
>>> long distance) but it goes back up to half way once I get back up to
>>> 50mph+
>>>
>>> I check the oil levels every so often just to make sure and it hasn't
>>> moved nor are there any leaks. Am I worrying for nothing or should get a
>>> mechanic to check it out?
>>>
>>> Its fine other than this, and everything else runs and drives nicely. Is
>>> it something to worry about or should the pressure guage move like this
>>> in all vans?
>>>
>>> thanks for any advice!
>>
>> 1986. How many miles?
>>
>> Two dynamics are happening he As the oil heats up it flows through the
>> system better, even though it is (hopefully...) a multigrade and your
>> Grandpa doesn't use straight 30 weight, the guage will go a little lower.
>>
>> The other is that things are wearing out in the bottom end of the engine,
>> and 'allowing' oil to flow in more passages than the original
>> manufacturing called for. Things to look for are piston bearings and
>> rods, rings (esp if it 'puffs' when started) and a weak oil pump.
>>
>> I mostly drive Toyotas. I have driven a Corolla like this for about 8
>> years. Just keep changing the oil regularly. I don't think an '86 is
>> worth a $6-1200 rebuild, unless the rest of the thing is in exceptional
>> condition.
>>
>
>

Interesting. I suppose until some other symptom develops I'll just tell him
to keep driving it.

I'd ask a mechanic to take a look at it, but as you said its not worth doing
any major work to it. Its really a beater car so I'm just going to keep my
fingers crossed.

You mentioned oil grades.

Does it really matter if he uses a synthetic or 10w30. I don't really know
much about these things but I assumed synthetics were what you put in
performace cars. What do you think? How often should I be changing it?

-thanks a bunch,


"Hachiroku" > wrote in message
news:c5tEf.6019$J81.449@trndny01...
>
> "slipandfall" > wrote in message
> ...
>> Oops, I meant to say 1996 about 110k. Sorry if this confuses the issue.
>> Same advice?
>
> Pretty much!
>
> I had a '92 FWD G'Vger with 229,000 miles on it, and the OP guage was
> steady as a rock!
> I have a '92 AWD G V'ger right now with 125,000, and the OP guage bottoms
> out (and I MEAN bottoms out) at lights and stop signs. You never know what
> an engine will take...
>
>>
>>
>> "Hachiroku" > wrote in message
>> news:HG6Ef.3901$UY3.2887@trndny05...
>>>
>>> "slipandfall" > wrote in message
>>> ...
>>>> Hi,
>>>>
>>>> A general question about my grandfather 86 Dodge Caravan...
>>>>
>>>> When you first start it up the Oil Pressure Guage (its a basic analog
>>>> dial like the speedometer, engine temp and such) goes up to 3/4 mark
>>>> between High and Low pressure.
>>>>
>>>> After driving it for 5 miles or so, it slowly floats down to half way
>>>> between High and Low pressure.
>>>>
>>>> After that if the speed drops below 20 or 30mph it settles down to 1/4
>>>> between High and Low pressure. It tends to stay there as long as the
>>>> speed stays below 30 (I notice it when I'm stuck behind a snowplow for
>>>> a long distance) but it goes back up to half way once I get back up to
>>>> 50mph+
>>>>
>>>> I check the oil levels every so often just to make sure and it hasn't
>>>> moved nor are there any leaks. Am I worrying for nothing or should get
>>>> a mechanic to check it out?
>>>>
>>>> Its fine other than this, and everything else runs and drives nicely.
>>>> Is it something to worry about or should the pressure guage move like
>>>> this in all vans?
>>>>
>>>> thanks for any advice!
>>>
>>> 1986. How many miles?
>>>
>>> Two dynamics are happening he As the oil heats up it flows through
>>> the system better, even though it is (hopefully...) a multigrade and
>>> your Grandpa doesn't use straight 30 weight, the guage will go a little
>>> lower.
>>>
>>> The other is that things are wearing out in the bottom end of the
>>> engine, and 'allowing' oil to flow in more passages than the original
>>> manufacturing called for. Things to look for are piston bearings and
>>> rods, rings (esp if it 'puffs' when started) and a weak oil pump.
>>>
>>> I mostly drive Toyotas. I have driven a Corolla like this for about 8
>>> years. Just keep changing the oil regularly. I don't think an '86 is
>>> worth a $6-1200 rebuild, unless the rest of the thing is in exceptional
>>> condition.
>>>
>>
>>
>
>

"slipandfall" > wrote in message
...
> Interesting. I suppose until some other symptom develops I'll just tell
> him to keep driving it.
>
> I'd ask a mechanic to take a look at it, but as you said its not worth
> doing any major work to it. Its really a beater car so I'm just going to
> keep my fingers crossed.
>
> You mentioned oil grades.
>
> Does it really matter if he uses a synthetic or 10w30. I don't really know
> much about these things but I assumed synthetics were what you put in
> performace cars. What do you think? How often should I be changing it?
>
> -thanks a bunch,

Perhaps Maxpower has a little more insight here. There are two schools of
thought, but you aren't really going to get that pressure guage up any
higher: Since it's a beater, run the cheaper Dino oil. Why spend the extra
for synthetic?

But, OTOH, a synthetic offers better protection against the wear that is
causing the problem, and may hold any failure off a little longer.

However, the key is, no matter what you choose: change the oil every 3K
miles! I have done this with 3 Toyotas and have gotten them all over 220,000
miles. I use Castrol GTX, 10W40 (they were older cars); the crankcases were
4 Qts, so I put in 3.5 Qts Castrol and 1 Qt Marvel Mystery Oil. Wear is
wear; all three engines don't hold the oil pressure like they used to, but
the 2 that I still have just keep running and running and running!


>
>
> "Hachiroku" > wrote in message
> news:c5tEf.6019$J81.449@trndny01...
>>
>> "slipandfall" > wrote in message
>> ...
>>> Oops, I meant to say 1996 about 110k. Sorry if this confuses the issue.
>>> Same advice?
>>
>> Pretty much!
>>
>> I had a '92 FWD G'Vger with 229,000 miles on it, and the OP guage was
>> steady as a rock!
>> I have a '92 AWD G V'ger right now with 125,000, and the OP guage bottoms
>> out (and I MEAN bottoms out) at lights and stop signs. You never know
>> what an engine will take...
>>
>>>
>>>
>>> "Hachiroku" > wrote in message
>>> news:HG6Ef.3901$UY3.2887@trndny05...
>>>>
>>>> "slipandfall" > wrote in message
>>>> ...
>>>>> Hi,
>>>>>
>>>>> A general question about my grandfather 86 Dodge Caravan...
>>>>>
>>>>> When you first start it up the Oil Pressure Guage (its a basic analog
>>>>> dial like the speedometer, engine temp and such) goes up to 3/4 mark
>>>>> between High and Low pressure.
>>>>>
>>>>> After driving it for 5 miles or so, it slowly floats down to half way
>>>>> between High and Low pressure.
>>>>>
>>>>> After that if the speed drops below 20 or 30mph it settles down to 1/4
>>>>> between High and Low pressure. It tends to stay there as long as the
>>>>> speed stays below 30 (I notice it when I'm stuck behind a snowplow for
>>>>> a long distance) but it goes back up to half way once I get back up to
>>>>> 50mph+
>>>>>
>>>>> I check the oil levels every so often just to make sure and it hasn't
>>>>> moved nor are there any leaks. Am I worrying for nothing or should get
>>>>> a mechanic to check it out?
>>>>>
>>>>> Its fine other than this, and everything else runs and drives nicely.
>>>>> Is it something to worry about or should the pressure guage move like
>>>>> this in all vans?
>>>>>
>>>>> thanks for any advice!
>>>>
>>>> 1986. How many miles?
>>>>
>>>> Two dynamics are happening he As the oil heats up it flows through
>>>> the system better, even though it is (hopefully...) a multigrade and
>>>> your Grandpa doesn't use straight 30 weight, the guage will go a little
>>>> lower.
>>>>
>>>> The other is that things are wearing out in the bottom end of the
>>>> engine, and 'allowing' oil to flow in more passages than the original
>>>> manufacturing called for. Things to look for are piston bearings and
>>>> rods, rings (esp if it 'puffs' when started) and a weak oil pump.
>>>>
>>>> I mostly drive Toyotas. I have driven a Corolla like this for about 8
>>>> years. Just keep changing the oil regularly. I don't think an '86 is
>>>> worth a $6-1200 rebuild, unless the rest of the thing is in exceptional
>>>> condition.
>>>>
>>>
>>>
>>
>>
>
>

I had the very simialr problem with my 89 dodge dynasty. Initailly the
oil pressure scale was between half and 2/3; Laterly It dropped to 1/2-
1/3 range. I have a mechanic check the pressure, and he told me the
pressures are ok but something wrong with my intrumental panel. I drive
the car for about 20k like that. I donot know if it is realed but, my
odometer stop working, and fuel level gauge interminently stop working.
I think i need to change my instrumental panel. ($15 at a local junk
yard)

Lately, I start to get leak from crank shaft seal. I donot know the low
oil pressure is due to about the go bad oil pump seals.

I have 208 kmile (the odometer stopped at about 6 months ago. )

My '94 Caravan 3.3 and my '90 Dakota 3.9 both read low oil pressure
at operating temp. I think they're inaccurate.
I thought I'd seen it mentioned in this discussion room several times
that Chrysler oil pressure gauges were notoriously "not-dependable."

"Hachiroku" > wrote in message
newscJEf.4497$0J3.3513@trndny08...
>
> "slipandfall" > wrote in message
> ...
> > Interesting. I suppose until some other symptom develops I'll just tell
> > him to keep driving it.
> >
> > I'd ask a mechanic to take a look at it, but as you said its not worth
> > doing any major work to it. Its really a beater car so I'm just going to
> > keep my fingers crossed.
> >
> > You mentioned oil grades.
> >
> > Does it really matter if he uses a synthetic or 10w30. I don't really
know
> > much about these things but I assumed synthetics were what you put in
> > performace cars. What do you think? How often should I be changing it?
> >
> > -thanks a bunch,
>
> Perhaps Maxpower has a little more insight here. There are two schools of
> thought, but you aren't really going to get that pressure guage up any
> higher: Since it's a beater, run the cheaper Dino oil. Why spend the extra
> for synthetic?
>
> But, OTOH, a synthetic offers better protection against the wear that is
> causing the problem, and may hold any failure off a little longer.
>
> However, the key is, no matter what you choose: change the oil every 3K
> miles! I have done this with 3 Toyotas and have gotten them all over
220,000
> miles. I use Castrol GTX, 10W40 (they were older cars); the crankcases
were
> 4 Qts, so I put in 3.5 Qts Castrol and 1 Qt Marvel Mystery Oil. Wear is
> wear; all three engines don't hold the oil pressure like they used to, but
> the 2 that I still have just keep running and running and running!
>
>
> >
> >
> > "Hachiroku" > wrote in message
> > news:c5tEf.6019$J81.449@trndny01...
> >>
> >> "slipandfall" > wrote in message
> >> ...
> >>> Oops, I meant to say 1996 about 110k. Sorry if this confuses the
issue.
> >>> Same advice?
> >>
> >> Pretty much!
> >>
> >> I had a '92 FWD G'Vger with 229,000 miles on it, and the OP guage was
> >> steady as a rock!
> >> I have a '92 AWD G V'ger right now with 125,000, and the OP guage
bottoms
> >> out (and I MEAN bottoms out) at lights and stop signs. You never know
> >> what an engine will take...
> >>
> >>>
> >>>
> >>> "Hachiroku" > wrote in message
> >>> news:HG6Ef.3901$UY3.2887@trndny05...
> >>>>
> >>>> "slipandfall" > wrote in message
> >>>> ...
> >>>>> Hi,
> >>>>>
> >>>>> A general question about my grandfather 86 Dodge Caravan...
> >>>>>
> >>>>> When you first start it up the Oil Pressure Guage (its a basic
analog
> >>>>> dial like the speedometer, engine temp and such) goes up to 3/4 mark
> >>>>> between High and Low pressure.
> >>>>>
> >>>>> After driving it for 5 miles or so, it slowly floats down to half
way
> >>>>> between High and Low pressure.
> >>>>>
> >>>>> After that if the speed drops below 20 or 30mph it settles down to
1/4
> >>>>> between High and Low pressure. It tends to stay there as long as the
> >>>>> speed stays below 30 (I notice it when I'm stuck behind a snowplow
for
> >>>>> a long distance) but it goes back up to half way once I get back up
to
> >>>>> 50mph+
> >>>>>
> >>>>> I check the oil levels every so often just to make sure and it
hasn't
> >>>>> moved nor are there any leaks. Am I worrying for nothing or should
get
> >>>>> a mechanic to check it out?
> >>>>>
> >>>>> Its fine other than this, and everything else runs and drives
nicely.
> >>>>> Is it something to worry about or should the pressure guage move
like
> >>>>> this in all vans?
> >>>>>
> >>>>> thanks for any advice!
> >>>>
> >>>> 1986. How many miles?
> >>>>
> >>>> Two dynamics are happening he As the oil heats up it flows through
> >>>> the system better, even though it is (hopefully...) a multigrade and
> >>>> your Grandpa doesn't use straight 30 weight, the guage will go a
little
> >>>> lower.
> >>>>
> >>>> The other is that things are wearing out in the bottom end of the
> >>>> engine, and 'allowing' oil to flow in more passages than the original
> >>>> manufacturing called for. Things to look for are piston bearings and
> >>>> rods, rings (esp if it 'puffs' when started) and a weak oil pump.
> >>>>
> >>>> I mostly drive Toyotas. I have driven a Corolla like this for about 8
> >>>> years. Just keep changing the oil regularly. I don't think an '86 is
> >>>> worth a $6-1200 rebuild, unless the rest of the thing is in
exceptional
> >>>> condition.
> >>>>
> >>>
> >>>
> >>
> >>
> >
> >
>
>
I do not use synthetic oil, I change mine on all my vehicles at 3k. that's
good enough. Dirt and heat causes problems and keeping those elements away
will cause the engine to last a long time.
If an engine is already worn out or causing problems I don't believe any
kind of oil will help it out.

My opinion only
Glenn Beasley
Chrysler Tech

"James Goforth" > wrote in message
...
> My '94 Caravan 3.3 and my '90 Dakota 3.9 both read low oil pressure
> at operating temp. I think they're inaccurate.
> I thought I'd seen it mentioned in this discussion room several times
> that Chrysler oil pressure gauges were notoriously "not-dependable."
>

The problem was oil pressure sending unit leaking and giving false readings,
if you think it is wrong check pressure/replace the sending unit

Glenn Beasley
Chrysler Tech