Priming oil after rebuild

[sanibel sailor]

I am almost done rebuilding a Westerbeke W30. I used assembly lube on all bearings of course. Want to prime the oil lube system prior to first start. I know on gas engines, pull the distributor and use a drill on the drive to turn the oil pump. This is a modified gas engine. Will same approach work? Seems like a lot of force needed to start turning the whole thing, even if I pull injectors to decompress. Another member suggested a drill pump on a remote oil filter line, but I am concerned that suction from above rather than pressure from below won't lube the main/rod bearings.

[motion30]

I am going to go with pull the injectors and crank until you see a coil pressure

[a64pilot]

You can also supply pressurized oil into any gallery, like that one your oil pressure gauges hooks to. That is how I do it on aircraft engines, a small tank you put oil into that connects to shop air
However it’s probably not needed as you did use assembly lube.
Most just crank them up, don’t even de-compress, but I think decompressing is the smart way to go.

Actually it’s the cam and lifter that see the greatest stresses, and of course decompressing does nothing there.

Obviously if you can remove something and drive the pump directly like on a gas motor that works too.

[Lepke]

There are assembly lubes that are more like grease and dissolve into the oil. Works better, especially cam lobes and lifters, rocker arms,etc. Otherwise I'd use a pressure pump or oil filled tank under pressure connected to an oil port. Most engine wear occurs at startup, not just the first startup.

Cranking w/o the injectors will work fine. The bearings have little loading w/o combustion so the oil will flow freely. Using this method, I'd get oil up to the rockers, maybe with a couple short cranks rather than one long one - to spare the starter.
Have rags to catch the fuel from the open tubes.

[nhschneider]

Where’s the compression release when you need one? When I installed the new engine on our boat, I researched and found a combination lube oil change pump that could also be reversed and supply oil pressure to the oil galleries. I think if the engine I installed had a turbocharger, I would have installed the system and supplied oil pressure after shutting the engine down.

I appreciate your interest in having a well-lubed engine on its initial start up but I seriously doubt that it would have a significant impact on the overall life of the engine. When I was a heavy equipment mechanic, none of the shops or dealerships I worked in would ‘pre-lube’ a newly-overhauled engine save for assembling the engine with engine assembly grease.

Fair winds and calm seas.

[Jammer]

Originally Posted by a64pilot

You can also supply pressurized oil into any gallery, like that one your oil pressure gauges hooks to. That is how I do it on aircraft engines, a small tank you put oil into that connects to shop air.

I have done this from time to time also, including on diesels.


There isn't any real evidence that it helps even though it seems like a good idea. It's harmless.


I didn't do it on the last two rebuilds I did. Fill crankcase, turn key.

[Matsubob]

I use manual transmission lube for my rebuilds. At 90W, I have found it stays on the bearing surfaces until the engine can be spun enough to draw oil from the sump. The valve train, including cam and lifters have to wait the longest for oil to reach them, so these items need to be well coated during assembly because they are completely dry.

[a64pilot]

People have used almost everything successfully, many used to swear by Motor Honey, or STP.
I like Lubriplate, but think most anything slippery will work.

Only engines I have seen that MUST be pre-lubed are some Radial aircraft engines for first start, the P&W Whitney R-1340 will almost certainly spin its main rod bearing if you don’t.
However you have 9 cylinders and 1,340 cu in of engine running on one main bearing though
Engine will run and make power, but about a half hour later the oil psi will be real low, and the oil temp real high, and the oil screens will be full of metal.

[stormalong]

Since we are talking about a diesel engine all you have to do is pull the stop lever or activate the stop solenoid and crank the engine. I would limit the cranking to about 5 seconds with 30 seconds between crankings. As long as the stop in engaged the engine will not start. Pulling the injectors is wasted effort.

I use this method every spring after winter layup.

[leftbrainstuff]

We have a preoiler on our perkins 4-236. We run it everytime prior to starting. 4k+ hours and she blows no smoke, uses no oil, has no oil leaks and the engine oil stays fairly clean between changes.

We have a dedicated electric pump for preoiling which plumbs into the oil filter. The engine is not cranked until after pre oiling. Much simpler than cranking but firing.

The single best way to ensure longevity in any engine is pre oiling.

[Lepke]

A hydraulic accumulator is how many race engines are pre lubed. Looks like a cylinder but operates like a water pressure tank. There is a seal & piston in the cylinder and some pressure behind the piston, air pressure or spring pressure is most common. The cylinder has a valve that allows engine oil under pressure to fill the cylinder. Before the engine is shut down, the valve is closed and the oil in the cylinder remains under pressure. Just before starting, the valve is opened and oil pressure is restored to the engine. When the starter is energized, the engine is already at normal oil pressure.
You also see this on engines that have no operator and are remotely started, like oil field pumps and backup generators. The whole process of opening and closing the valve can be automatic.

[a64pilot]

Originally Posted by leftbrainstuff

The single best way to ensure longevity in any engine is pre oiling.

Pre-oilers were all the rage in the late 70’s, however they have all but disappeared.
Why? Because it apparently doesn’t do much if anything.
If you know of any actual testing to support your claim, I’d be interested in seeing it.

The basis of justification of a pre-oiler is the myth of most engine wear occurs at start up, which I’d like to see a study supporting that too, because it’s been shown to not be true by the many millions of automobiles who’s engines shut down at every red light etc.


There are so many accepted truisms with engines that are just plain false, but accepted and repeated by so many experts that you lose count.
Like the don’t use Syntjetic oil for the first xx thousand miles or the engine won’t break in synthetic oil is too slick.
Yet again many millions of cars for decades have come from the factory brand new with synthetic oil that surely no one would believe that anymore, yet I hear it all the time, from supposed experts.

[a64pilot]

The only possible benefit of pre-lubing would be to the bottom end, the crankshaft and rod bearings as well as the camshaft too, valve train also maybe.
However I bet that less than one in ten engines that need overhauling do so because of worn bottom end bearing or valve train.
Engines require overhauling because the cylinder rings are worn excessively causing low compression, and excessive oil consumption.

I’d tell you that the one thing that will life of an engine is frequent oil and filter changes, 100 hours as opposed to 250 etc.

[ggray]

While we are talking about "truisms", might be a good time to ask about one.

*Filling the oil filter when changing the oil.*

Does this really do any good?

[a64pilot]

Originally Posted by ggray

While we are talking about "truisms", might be a good time to ask about one.

*Filling the oil filter when changing the oil.*

Does this really do any good?

In my opinion, yes it may do a little good.
Why? Because it shortens the time that the engine runs with no oil pressure, cost nothing to do, and isn’t hard to accomplish.
Of course only possible on a few engines that have their filters mounted with the open end up.
Is it absolutely necessary? Obviously not, cause most engines you can’t do it, and they don’t seem to die early deaths. Plus you can bet that only a few owners regularly do it, the oil change place isn’t going to bother, it takes time and time is money.

Now I’m not against pre-lubing an engine for example, it can’t hurt, has to do some good, but unfortunately it hasn’t been shown to make an engine last any longer.

It should be remembered there are millions of small engines with no oil pump at all, and even automotive engines back in the day were done that way, only splash lubrication.
As long as there is oil there and an engine isn’t under much load, it can tolerate no oil pressure for a short time.
What is different in an engine with an oil pump is that the power that can be made out of a engine is much greater, a splash lubricated engines power limit is much lower before it will wipe out a main bearing.
Aircraft engines were the first to get full oil pressure lubrication so that they could make more power per cu in.
It’s for this reason that during the early part of WWII that you would find aircraft engines in strange places, like tanks and I believe boats for instance.