A Simple Method for Pre-Oiling an Engine

[Ronmar]

In my tests in a bucket, the air pipe(very similar to that pictured) only lifted the oil above the blowhole in the pipe.  It was unable to bring the oil level below that point, so anything on the bottom should stay there...

[BruceM]

I've got compressed air at my Metro 6/1, so I'm intrigued about pre-oiling.  Is that likely to make a big difference for longevity?  Operationally my engine gets run only a few hours a week, unless I've got a big project in the shop, or we get some very dark weather.

[Horsepoor]

Pre-oiling is a more significant concern to me because both of my engines sit for weeks or months between starts. I always check the oil level before a start, but I know all the other internal parts are dry. So finding a simple method to spash some oil around inside the crankcase for under $10 and an hour worth of labor just made sense to me.

[Ronmar]

I recall an old OIT engine study where they did repeated startup and shutdown tests on 2 identical engines, one with prelube, and one without.  They confirmed that the majority of wear was incurred during startup before oil pressure was established.  On a diesel with high compression loads, and splash lubed big end and rod bearings, it makes a lot of sense to me to splash that rod really well to flood the big end bearing lube oil holes and give it a little time to spread out in the bearing before those first compression loades are applied.  Otherwise, it cranks and starts and needs to get up to speed before good splash is even delivered, then that splashed oil has to build up on the rod and then run down the rod and into the bearing holes, then spread out and build the oil film in the bearing... 

How many compressions and firings occur before oil supply is established to the rod bearings?

[BruceM]

Good point, Ronmar.  Alas I use a solid upper bearing and hollow dipper on the big end bearing. That rules out splash pre-lube, I suppose. 

[sailawayrb]

When I was running with the standard solid core dipper, the big end bearing was also full of oil every time I cracked it open for inspection...even after not running for months...

I have been running the hollow core dipper and plain upper bearing for about 6 years now and the big end bearing does not retain the oil for very long.  However, the hollow core dipper likely pressurizes and refills the big end bearing within a couple compression firings.  This arrangement certainly appears to be far superior to the standard setup in terms of wear.

It certainly doesn't hurt to oil the engine well before starting it if it hasn't been started in a while...as long as you are not introducing crude into the bearings.  

However, I think I would be more concerned about the TRBs and the cam shaft bushings.  In fact, I would be concerned about just getting adequate oil to cam shaft bushings in general.  When we evaluated this situation several years ago, many of us incorporated devices directly above these bushings that would collect the oil mist and allow it to drip into the cam shaft holes.

Bob B.

[Ronmar]

Bruce, but the hollow dipper most likley has oil to the big end in just a few revolutions.  but this does nothing for the little end bush which has less surface area but the same load applied...

Bob, This lube method should also prelube the TRB and cam bushings well as it just blows oil all over the place.  I also use the "reed in the mist" method to deliver more oil to the cam end bushing.  Because it is back in behind the governbor flyweight/gear, I am most worried about the bush on the IP end of the cam. 

[fabricator]

In the real world, an engine that is run up to temperature and run continuously except for maintenance shut downs will out last an engine that is run off and on by a long shot, I believe that is the reason there are so many reports of the original CS engines running 24/7 for years.

[BruceM]

I also copied the "reed in the mist" design presented here many years ago, as it seemed a good way to get a little more oil to the "far side" camshaft bearing, where Lister put the manual oil access plug. I manually oil it also.  

Since I do remote starts 80% of the time, I'm thinking of an automatic pre-oiling rig- not as simple, alas.

Targeting both cam shaft ends and TRB's is doable, and I suppose the small rod end could generally be sprayed, despite not being in a consistent position.  I'm thinking something like a few lengths of 1/4" copper tubing glued in place with epoxy steel inside the case to direct the air/oil blast, and bring out the air line through the case via copper as well. A little sump submerged oil reservoir "can" could have a silicone flap over a small hole (check valve) so that it would fill slowly with oil when air pressure was not present. Then you could have a real oil squirter. But perhaps a compressed air venturi design to atomize a smaller amount of oil drawn from the top of the sump is best. Induced oil draft?  

One problem I just thought of- all the oil mist would be blown out of the case through the vent check valve in the case of an air-oil venturi.  Maybe the squirter approach would be better.  

Since my setup always shuts down with decompression, on shut down, both rod bearings do get plenty of oil and no load to force it out...right???

[Horsepoor]

I forgot what the "reed in the mist" was called. A couple of years ago I read about this, drilled a vertical hole in the bolt, inserted a taped and threaded welding rod into the hole, later added JB weld, oil mist hits the short stubby welding rod and drips oil onto the shaft / bushing -works great. Lots of oil in the far end cam bushing when running. On my twin, this bolt hole is where the oil return line connects after exiting the motor guard by pass filter, also works great. For several years I rarely posted, but read daily on the thread, implementing as much as I could. Forum is a great source of information. So, where in the USA can I buy several sets of solid upper bearing shells to compliment my spares inventory? Oh, I forgot to add this observation. During my 2005 sand clean out tear down on my "new" engine, I found the little triangle strips of metal used to shim the bearing shells still had the coca cola emblems on it. Apparently the same metal they used to make the hinge corners of the wooden shipping crate. You got to love the craftsmanship!

[Ronmar]

One problem I just thought of- all the oil mist would be blown out of the case through the vent check valve in the case of an air-oil venturi.  Maybe the squirter approach would be better.  

Since my setup always shuts down with decompression, on shut down, both rod bearings do get plenty of oil and no load to force it out...right???

No need to get as involved as a venturi.  One or more 1/8" ID pipes, or a horizontal pipe with 1 or more holes along the top, installed 1/8"-1/2" below the oil level, with a little air applied will lift ALL the oil above the holes up and into the engine case if the air is allowed to flow long enough. The pipe will of course fill with oil, so all that oil will get blown out first.  As for oil mist, 1/8" holes below the oil level don't make much mist, especially when cold, just a lot of small to large drops, so you shouldn't see much of anything come out the case vent beyond air.  It really only takes a short blast or two of air to lift a LOT of oil and throughly coat the inside of the case and components...  If your startup process is automated, a timer and an air solenoid valve could be added to the front end of the start sequence.  Short blast, pause, short blast, pause 30-60 seconds to allow oil to percolate into bearing lube holes, then commence startup...

[BruceM]

Horsepoor,  JohnF at woodnstuff.ca is the only source I know of for solid upper bearings. He's where I got them.  I wonder if dieselgman is carrying them.

Thanks for the simpler solution, Ronmar.  The nice part about a DIY engine controller is that I can add this sort of thing without a big fuss, just plumb up one more small air solenoid.  I'm in the midst of an electronics/software project now but this seems like an easy and worthwhile small project.

[dieselgman]

Guys, if supply of the modified bearings (and hollow dippers to go along with) becomes an issue, we can investigate and stock them here. Up to this point we have left most of the modifications to others. Our forays into the clones is mostly as a service anyway and we prefer to tailor it to the real needs and gaps that might exist in the marketplace - not necessarily to compete with other viable sources, because the total demand is quite limited.

dieselgman

[TimSR2]

I'm not  big a believer in pre- lubrication. Pre lube is a sales gimmick.  Any decent motor oil should be able to provide enough boundary lubrication to support wear free start ups.  Far more engines die from ring and valve wear than main and rod bearing failure.  There is always an oil film  on all journals, despite how long the engine may sit out of service. Lister CS types don't have pressurized lubrication anyway so what's the difference? This is not a highly stressed engine design.


(Flame Shield ON) 

[Tom Reed]

And besides those of us with generators (most of us) should exorcize them once a month. If we keep the schedule it will keep the engines oiled and ready to go in an outage. I need my 'roid fix at least once a month anyway.

In fact this winter has been so dry and sunny, I've not had much run time on my 'roid. It is kind of sick  to get excited about rain/clouds so I can run the engine and listen to that sweet sound.