[AT] cub / prime oil pump

[Larry D. Goss]

Amen! Dean.  I remember seeing a presentation at an engineering
conference about 30 years ago concerning the problems of "thin film
lubrication" (that's what we're dealing with.)  The bottom line is that
unless you have an oil system that is capable of sustaining pressure in
the 100's of psi, the film is going to completely disappear at the
locations of extreme mechanical pressure for several degrees of rotation
of the crankshaft on every revolution.  It doesn't make any difference
what oil you're using -- it's going to happen.  What you hope for is
that during the intervening portions of the rotation enough oil gets
back into the journal to coat the surfaces once again and keep them cool
so that they don't gall.

Priming will help on startup.  But if you think your engine is running
under full load and at normal operating temperatures without regular
metal-to-metal contact on every revolution -- dream on.

Do the math on the combustion pressures compared to the oil pressure
spread over the extremely large difference in area of the line contact
on the journal and the area of the piston...

A high oil pressure means that recovery from the metal-to-metal contact
happens more quickly, but it doesn't prevent it.

Let the flames begin.

Larry

-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com] On Behalf Of Dean VP
Sent: Friday, June 10, 2005 10:36 PM
To: 'Antique tractor email discussion group'
Subject: RE: [AT] cub / prime oil pump

Gary:

Our antique tractors are supposed to have oil pressure? Oh my God, I
thought
they were all splash lubed! :-)

I tend to drain all fluids when I get a new (used) antique tractor on
the
yard. Then flush all cavities with Kerosene or Diesel fuel. Then I'm
quite
often starting out with no oil pressure. On most, if not all, of the
tractors, I have been able to get adequate oil pressure by hand cranking
them a bit before trying to start them. I failed to do that on one and
it
scared me to death because I watch the oil pressure gauge intensely when
starting something I'm not very familiar with. It didn't take long for
the
pressure to build but that momentary delay startled me and seemed like
eternity.  I suspect not much, if any, damage will be done to an engine
if
it has been running with oil pressure in the recent past. The cylinder
walls
should still be lubed and the bearings should still have a coat of
lubricant. I do get a bit nervous about the cylinder wall lubrication if
I've had a carburetor needle and seat failure on a gravity feed gas
tank.
When the gasoline fills the cylinder it washes off the lubricant.  

However, in real life, I've brought back enough tractors to life with
all
new fluids in them that were so much an improvement over what had been
in
there before that I suspect all the surfaces breathed a sigh of relief.
If
there was going to be any damage, due to momentary shortage of oil
pressure,
it would be very minor compared to the damage done with the filthy,
water
logged oil that had been in there previously. The old engines are so dog
gone tolerant and loose toleranced that we sometimes mix today's tight
toleranced engine requirements with 50 year old technology. 

I've come to the conclusion that I can even have an occasional "senior
moment" and forget to do something right and not hurt them very much at
all.
I'm not nearly as uptight about it as I once was. Maybe that will get me
into trouble, but I doubt it. If they could handle farmer abuse for
years,
they can handle my occasional memory lapses. 

Dean A. Van Peursem
Snohomish, WA 98290

I'm a walking storeroom of facts..... I've just lost the key to the
storeroom door 


www.deerelegacy.com

http://members.cox.net/classicweb/email.htm



-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com] On Behalf Of K7jdj at aol.com
Sent: Friday, June 10, 2005 9:47 AM
To: at at lists.antique-tractor.com
Subject: Re: [AT] cub / prime oil pump

In a message dated 6/10/2005 7:42:20 AM Pacific  Standard Time, 
wild1 at cpe-66-1-196-61.az.sprintbbd.net writes:
Smart start-up  procedures and regular maintenance
go a long way toward keeping this old iron  running.

Good comments Ken.  A Google search turned up a a lot of  site
addressing 
lub-oil issues.  Here a couple I looked  at.

http://www.thirskauto.net/Oil_Pumps.html

http://dodgeram.org/ki4cy/preluber/Preluber.htm

Although  this thread has drifted a bit from the original post, I think
many

of our old  antique
machines sit idle for extended periods and it is a good idea to pay  
attention to the oil pressure issue at start up. 

Gary
Renton, WA  

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