No Oil Pressure?!

Technical aspects of automobiles, et. al., post #20,469
Author:
Date:
Subject:
 TomO
 2008-06-16 12:56:01
 No Oil Pressure?!
I'm dealing with a 1982 motorhome that's powered by a Chevy 454 on a
P-30 chassis with about 100k miles on it.

Motorhome was parked for 9 months or so, and when I started it yesterday,
there was no oil pressure! I checked the level and found it to be about
three quarts low. I know, my bad. I topped off the level and started, but
still no pressure. The total run time in this condition is about 10
seconds or so, so I'm hoping that I haven't totally ruined anything yet.

Now I'm wondering if I can come up with a way to try and prime the pump
without running the motor. Is it possible to pull the distributor and
operate the oil pump with a drill motor and some sort of suitable shaft?

What could have failed if it's not just a case of the pickup tube not
reaching the too-low oil level? Pump going bad while parked ( there were
no problems last trip we took in this rig )? Could a plugged filter cause
a no pressure situation? Any other ideas? How do you troubleshoot a no
oil pressure condition without running the motor?

I don't yet know if I can drop the pan while the engine is still mounted
in this rig. I may have to try and find a way to push it into the barn
where I can get underneath and poke around.

Thanks for your shared wisdom.

--
TomO
Author:
Date:
Subject:
 boxing@sasktel.net
 2008-06-16 06:07:52
 Re: No Oil Pressure?!
Maybe its just the sending unit that is shot. It probably would not
hurt to change the oil and filter.
Author:
Date:
Subject:
 HLS
 2008-06-16 08:40:41
 Re: No Oil Pressure?!
<[email protected]> wrote in message
news:7b0a6cc4-feb0-4abe-b79f-b50b9ac4a3c5@m3g2000hsc.googlegroups.com...
> Maybe its just the sending unit that is shot. It probably would not
> hurt to change the oil and filter.

Good starting place, to be sure the indicator is working.

I dont know those engines, but in general, sludge, loose oil pickup, bad
pump,
snapped oil pump drive shafts have plagued a variety of other engine
designs.
Author:
Date:
Subject:
 TomO
 2008-06-16 14:40:54
 Re: No Oil Pressure?!
On Mon, 16 Jun 2008 06:07:52 -0700, boxing wrote:

> Maybe its just the sending unit that is shot. It probably would not hurt
> to change the oil and filter.


That was my first thought/hope, but the valve train was rattling quite a
bit more than what is usual for this engine. I don't want to run it any
more until I find out for sure.

--
TomO
Author:
Date:
Subject:
 lugnut
 2008-06-16 10:22:59
 Re: No Oil Pressure?!
On 16 Jun 2008 12:56:01 GMT, TomO <[email protected]>
wrote:

>I'm dealing with a 1982 motorhome that's powered by a Chevy 454 on a
>P-30 chassis with about 100k miles on it.
>
>Motorhome was parked for 9 months or so, and when I started it yesterday,
>there was no oil pressure! I checked the level and found it to be about
>three quarts low. I know, my bad. I topped off the level and started, but
>still no pressure. The total run time in this condition is about 10
>seconds or so, so I'm hoping that I haven't totally ruined anything yet.
>
>Now I'm wondering if I can come up with a way to try and prime the pump
>without running the motor. Is it possible to pull the distributor and
>operate the oil pump with a drill motor and some sort of suitable shaft?
>
>What could have failed if it's not just a case of the pickup tube not
>reaching the too-low oil level? Pump going bad while parked ( there were
>no problems last trip we took in this rig )? Could a plugged filter cause
>a no pressure situation? Any other ideas? How do you troubleshoot a no
>oil pressure condition without running the motor?
>
>I don't yet know if I can drop the pan while the engine is still mounted
>in this rig. I may have to try and find a way to push it into the barn
>where I can get underneath and poke around.
>
>Thanks for your shared wisdom.


The first thing I would look for is a bad pressure switch.
I would also substitute a mechanical guage to find out
exactly if and how much pressure it has. If you only have a
light, it may be that the pressure awas low when it was last
running. IIRC, those pressure switches are set to come on
around 5-7 psig which ain't much but is adequate for hot
idling. If it never went anything above the pressure needed
to turn off the light, you will never know with a warnig
light only system. 100K is a lot on a gasoline MH engine
simply because it is under a fairly constant high load.

Lugnut
Author:
Date:
Subject:
 TomO
 2008-06-16 14:46:40
 Re: No Oil Pressure?!
On Mon, 16 Jun 2008 10:22:59 -0400, lugnut wrote:
>
> The first thing I would look for is a bad pressure switch. I would also
> substitute a mechanical guage to find out exactly if and how much
> pressure it has. If you only have a light, it may be that the pressure
> awas low when it was last running. IIRC, those pressure switches are
> set to come on around 5-7 psig which ain't much but is adequate for hot
> idling. If it never went anything above the pressure needed to turn off
> the light, you will never know with a warnig light only system. 100K is
> a lot on a gasoline MH engine simply because it is under a fairly
> constant high load.
>
> Lugnut

The valve train was rather noisy as well; enough to make me shut it down
immediately and not want to re-start until I have more information. And
this thing does have an electric pressure gauge as part of the instrument
cluster.

This engine had not been run at all for at least 9 months, maybe a few
more. There were no problems with oil pressure when I parked it last
summer.

--
TomO

Normally the dashboard gauge reads about 40 PSI on a cold start, but this
time it did not budge.
Author:
Date:
Subject:
 lugnut
 2008-06-16 11:40:16
 Re: No Oil Pressure?!
On 16 Jun 2008 14:46:40 GMT, TomO <[email protected]>
wrote:

>On Mon, 16 Jun 2008 10:22:59 -0400, lugnut wrote:
>>
>> The first thing I would look for is a bad pressure switch. I would also
>> substitute a mechanical guage to find out exactly if and how much
>> pressure it has. If you only have a light, it may be that the pressure
>> awas low when it was last running. IIRC, those pressure switches are
>> set to come on around 5-7 psig which ain't much but is adequate for hot
>> idling. If it never went anything above the pressure needed to turn off
>> the light, you will never know with a warnig light only system. 100K is
>> a lot on a gasoline MH engine simply because it is under a fairly
>> constant high load.
>>
>> Lugnut
>
>The valve train was rather noisy as well; enough to make me shut it down
>immediately and not want to re-start until I have more information. And
>this thing does have an electric pressure gauge as part of the instrument
>cluster.
>
>This engine had not been run at all for at least 9 months, maybe a few
>more. There were no problems with oil pressure when I parked it last
>summer.


You can get an adapter shaft to run the oil pump with a good
drill from most auto parts stores. Many will have to order
it for you. It is designed for priming an oil system on
freshly built engines. Remove the distributor and make sure
the drill is turning it the same direction as the
distributor turns. If you have a guage connected, you
should see pressure build. Also, at 100K miles, it may be a
matter of a plugged oil pickup screen. It may have sat long
enough for sludge to settle from the oil to the bottom of
the pan just to get sucked up like the dry film that forms
on the surface of paint in long term storage. If that is
the case, you may get away with a pan gasket to clean the
pan. Be sure to change the new oil after a couple hundred
miles just in case it starts again. Having been 3 qts low,
I would suspect the oil was quite hot when it last ran which
can break down the oil and cause it to be more like grease
than oil when it cools.

Lugnut
Author:
Date:
Subject:
 TomO
 2008-06-16 21:51:38
 Re: No Oil Pressure?!
On Mon, 16 Jun 2008 11:40:16 -0400, lugnut wrote:

>
> You can get an adapter shaft to run the oil pump with a good drill from
> most auto parts stores. Many will have to order it for you. It is
> designed for priming an oil system on freshly built engines. Remove the
> distributor and make sure the drill is turning it the same direction as
> the distributor turns. If you have a guage connected, you should see
> pressure build. Also, at 100K miles, it may be a matter of a plugged
> oil pickup screen. It may have sat long enough for sludge to settle
> from the oil to the bottom of the pan just to get sucked up like the dry
> film that forms on the surface of paint in long term storage. If that
> is the case, you may get away with a pan gasket to clean the pan. Be
> sure to change the new oil after a couple hundred miles just in case it
> starts again. Having been 3 qts low, I would suspect the oil was quite
> hot when it last ran which can break down the oil and cause it to be
> more like grease than oil when it cools.
>
> Lugnut

Thanks for that.

I'll look into a way to spin the pump and hope that I was just sucking
air. That would be the easiest solution for me. I have pretty easy access
to the top of the engine with the doghouse removed in this vehicle.

Otherwise, I'll have to hope that I can get the pan off with the
motorhome on the ground and the block still in place. I'm not looking
forward to rolling around in the weeds where she's currently parked
behind the barn, but what can I do? Maybe I can find a way to push this
beast into the barn without damaging anything, but I'll need to get
creative. Once in the barn, though, there isn't more than a few inches of
clearance to lift this thing if need be. I should have built a taller
barn or poured a pad outside somewhere. Live and learn.

--
TomO