Rislone/oil pressure switch

D

dave1

New member
Jul 23, 1998
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>Also, anyone know if there is a replacement for the oil pressure switch
>(aftermarket) or if it usually just needs tightening when leakage
>occurs?

You may want to replace it soon. Mine leaked for a couple years and then
one day, all of a sudden, the diaphragm broke and emptied four quarts of
oil all over the place. Fortunately the switch still worked and shut down
when all of the oil was gone. But it was a long hot drive home that day....

Dave
73 Sequoia
 
Dave,
I can't believe the timeliness of this post! On Sunday on
the way home from my recent trip, after parking for a pit stop
I noticed a puddle of oil under the cooling air discharge vent
of my Onan. I made sure that the oil filter was on tight and
it was. My fear of course was that it was the main crank oil
seal leaking (it still could be). I decided to not run the Onan
the last 250 miles to home. Fortunately it turned a bit cooler
and the passengers were not too hot (only in the low 80's).

After reading this post I decided to take a closer look. I
removed the Blower Housing Cover and the Right Cylinder
Head Cover (near the oil filter). It's pretty oily in there, but it
sure looks like the Low Oil Pressure Switch could be leaking
right at the end where the wire attaches.

So I'll get a new switch and see what happens.

- ----

> >Also, anyone know if there is a replacement for the oil pressure switch
> >(aftermarket) or if it usually just needs tightening when leakage
> >occurs?
>
> You may want to replace it soon. Mine leaked for a couple years and then
> one day, all of a sudden, the diaphragm broke and emptied four quarts of
> oil all over the place. Fortunately the switch still worked and shut down
> when all of the oil was gone. But it was a long hot drive home that day....
>
> Dave
> 73 Sequoia
 
Rick,
Thanks for the "heads up" on the oil filter
adapter and bracket. I just looked and they appear to
be dry. To be on the safe side I made sure they were
still tight. You are right the setup is right from Walt
Disney! I have basically the same engine in my garden
tractor (Onan 22 HP) and so I am used to such things.

I ran the engine with the cylinder head shroud
off to see if I could detect oil coming from the low oil
pressure switch. Sure enough, shortly after starting, drops
started to came out of it about every few seconds. It
sounds like, based on the other posts on this subject,
that could have been the start of a real gusher if left alone.
I am fortunate to have discovered it early on instead of
after the fact.

I'll go to the local Onan distributor on Friday
to get the replacement part and some oil filters as I doubt
I can get good substitutes at my auto parts store.
Richard
- ---

>
> While you're in there, double-check the nuts holding the oil filter
> adaptor AND motor mount to the crankcase. Mine loosened up, causing a
> sudden and massive oil leak out the blower outlet. I was sure it was the
> front crankshaft seal (even bought a replacement seal), but it wasn't. Being
> loose caused the gaskets to blow out, (filter adaptor to mount, mount to
> crankcase). I cut new ones out of gasket paper, with a little gasket sealer
> they're still holding 3 years later.
> This is one Onan design which is NOT very reliable. The outer engine
> mount is a piece of flat steel bar stock running vertically alongside the
> crankcase, and attached to it by the same two studs and nuts that hold the
> oil filter adaptor on. Oil under full pressure passes to and from the filter
> via two holes drilled through the mounting strap. Mickey Mouse.
>
> My .02, HTH.
>
> Rick Staples
> '75 Eleganza
> Louisville, CO
 
Rick,
Any of the following filter will fit the onan.

Fram PH-28A of PH2870, Hasting 134, Lee LP-2131, Mopar -323, Motorcraft
FL-271, Purolator FCO-252 and I use the AutoZone Deutsch D484 and Most
are under $4. The Onan filter will cost you.

J.R. Wright
GMC GreatLakers
77 Eleganza II
Michigan

>
> Rick,
> Thanks for the "heads up" on the oil filter
> adapter and bracket. I just looked and they appear to
> be dry. To be on the safe side I made sure they were
> still tight. You are right the setup is right from Walt
> Disney! I have basically the same engine in my garden
> tractor (Onan 22 HP) and so I am used to such things.
>
> I ran the engine with the cylinder head shroud
> off to see if I could detect oil coming from the low oil
> pressure switch. Sure enough, shortly after starting, drops
> started to came out of it about every few seconds. It
> sounds like, based on the other posts on this subject,
> that could have been the start of a real gusher if left alone.
> I am fortunate to have discovered it early on instead of
> after the fact.
>
> I'll go to the local Onan distributor on Friday
> to get the replacement part and some oil filters as I doubt
> I can get good substitutes at my auto parts store.
> Richard
> ---

>

> >
> > While you're in there, double-check the nuts holding the oil filter
> > adaptor AND motor mount to the crankcase. Mine loosened up, causing a
> > sudden and massive oil leak out the blower outlet. I was sure it was the
> > front crankshaft seal (even bought a replacement seal), but it wasn't. Being
> > loose caused the gaskets to blow out, (filter adaptor to mount, mount to
> > crankcase). I cut new ones out of gasket paper, with a little gasket sealer
> > they're still holding 3 years later.
> > This is one Onan design which is NOT very reliable. The outer engine
> > mount is a piece of flat steel bar stock running vertically alongside the
> > crankcase, and attached to it by the same two studs and nuts that hold the
> > oil filter adaptor on. Oil under full pressure passes to and from the filter
> > via two holes drilled through the mounting strap. Mickey Mouse.
> >
> > My .02, HTH.
> >
> > Rick Staples
> > '75 Eleganza
> > Louisville, CO
 
Rick
FWIW I had the 4KW Onan on my 73 rebuilt at the local Onan dealer about
2 yrs ago. They replaced the after mkt oil filter with an Onan.

Sometime later during a pre trip inspection I pulled the Genset out to
ck oil and noticed the bottom of the Onan filter was rubbing against the
side of the Genset drawer.Could have been a big time problem had I not
detected it.

Replaced it with a Fram (a little bit shorter)
If yours is a 6KW it may be a different setup just beware. Good Luck

Dick Missett
Wyoming , PA
 
>Dave,
>I can't believe the timeliness of this post! On Sunday on
>the way home from my recent trip, after parking for a pit stop
>I noticed a puddle of oil under the cooling air discharge vent
>of my Onan. ... pretty oily in there, but it
>sure looks like the Low Oil Pressure Switch could be leaking
>right at the end where the wire attaches.

Another area that leaks is the oil filter casting where it attaches to the
engine. Its a funky arrangement with the engine mount bracket sandwiched in
between the engine and the oil filter mount. There are only two screws
holding it and the casting is soft aluminum. I don't know if its the weight
of the engine, the weight of the oil filter or the fact that the top of the
oil filter sometimes rubs on the drawer (when closing the drawer) but the
gasket between the engine mount and the oil filter casting works loose and
leaks. I have had to replace it a couple times.

Also one of the bolts on the timing chain cover has a pressurized oil
passage behind it. If the bolt is loose or if the timing chain cover gasket
or the copper washer on the bolt is worn, this will leak too.

There is a lot of stuff at that end of the engine that can leak. Leaks are
not very easy to find because the air flow blows oil all over the place.

Something else to check is the check valve in the top of the crankcase.
This check valve should maintain a vacuum inside of the crankcase. If this
valve is working properly then the crank seals and other gaskets rarely
leak. There are a couple of read valves under the crankcase vent cover (on
top of the engine). You can take the cover off and check to see that they
are clean and working properly. But my experience is that oil leaks are
usually on the pressure side of the oil system.

Dave
73 Sequoia
 
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