Pre-Oiler for Yanmar

[AdamC]

Greetings All,

Has anyone engineered a pre-oiler system onto their Yanmar 4LH or similar engine? If so, I'd love to hear the details.

I suppose this would also be a good time to invite comments on pros and cons of pre-oiler systems in general. Does anyone think they are not beneficial or more trouble than they're worth?

Thanks,
-Adam

 

[gsholz]

Not needed. Recreational marine engines generally wear out because of marine age (years in salt water) not lack of lubrication at start up.

If you are really paranoid, some engines allow you to push the "stop" switch while cranking. Once you see oil pressure building, you release the stop switch and the engine fires. But again, not aware of any recreational marine engine that wore out because of lack of prelubing.

 

[DavidM]

Not needed. Recreational marine engines generally wear out because of marine age (years in salt water) not lack of lubrication at start up.

If you are really paranoid, some engines allow you to push the "stop" switch while cranking. Once you see oil pressure building, you release the stop switch and the engine fires. But again, not aware of any recreational marine engine that wore out because of lack of prelubing.

Tony Athens said much the same thing, many years ago over on boatdiesel. Big commercial diesels may benefit from prelubing, but not our recreational engines.

David

 

[Bacchus]

Not needed. Recreational marine engines generally wear out because of marine age (years in salt water) not lack of lubrication at start up.

If you are really paranoid, some engines allow you to push the "stop" switch while cranking. Once you see oil pressure building, you release the stop switch and the engine fires. But again, not aware of any recreational marine engine that wore out because of lack of prelubing.

The Yanmar 6LYA manual mentions cranking while holding stop switch for starting after extended shut down as a way to lube before firing the engine.
I dont see a need on recreational use engines.

 

[AdamC]

Thanks Gents. I would tend to agree that it should not be needed. I don't think I'm paranoid. However, my Port engine takes "forever" to generate oil pressure. I'll post a video to show you what I mean. I don't know how it's possible, but sometimes I have to wait 45-60 seconds with the oil pressure pin-low at idle. I installed a mechanical gauge inline with the sender, just to be sure its not an instrumentation problem. It always comes up to normal.....eventually, and not gradually. Just all of a sudden, boom, 45 psi. Stbd engine shows pressure in 5-10 seconds.

I'll post a video when I get'r back on the water.

-Adam

 

[C lectric]

I did it. As much for the exercise as anything but I have never been sorry.
It was ~25 yrs ago.
I got ahold of a hydraulic pump set for free from a trashed pallet jack. I have no idea of the pressure it was capable of generating or the volume it can pump.

I used an adjustable check valve to limit the pressure to 100PSI and tested it at home with a pressure guage to be sure. The check valve was mounted in a bypass line back to the pump intake to simply recirculate the oil if the pressure was high enough to open the check valve.

I will warn though that my unit draws about 80 amps when running. I used a Cole Hersey continuous duty relay to activate it. I also now use a Cole Hersey OFF/MOM ON switch to operate it, the relay. That way when I have pressure I just let go. AND VERY IMPORTANT, I cannot forget to turn it off which I did once and an hour later the motor was cooked along with the alternator.

After running it for startup about 25-30 seconds I turn on the ign. sw. so the alarms are alive, the low oil pressure. As soon as the oil press. needle moves and the alarm quits I shut the pump off. Then I start the engine and have full pressure almost immediately.

It also helps at oil change time however I don't run it continuously for the total time. Rather 30- 40 seconds and then leave it for 10-20 minutes, then go again in the same cycle untill I see pressure on the needle and the alarm noise stops It will fill the filters and charge the oil galleries for near instant pressure. My engine holds about 30 litres so it takes some time.

I also used hydraulic fittings to create a small oil reservoir at the pump inlet so the pump has oil immediately. Stopped the noise of an unprimed pump which is not nice.

If I were to do it again I think I would try one of the ones I see advertised simply because they can provide much lower pressure and greater volume.
However it was a neat project and the cost was workable.

Have fun.

 

[rslifkin]

Thanks Gents. I would tend to agree that it should not be needed. I don't think I'm paranoid. However, my Port engine takes "forever" to generate oil pressure. I'll post a video to show you what I mean. I don't know how it's possible, but sometimes I have to wait 45-60 seconds with the oil pressure pin-low at idle. I installed a mechanical gauge inline with the sender, just to be sure its not an instrumentation problem. It always comes up to normal.....eventually, and not gradually. Just all of a sudden, boom, 45 psi. Stbd engine shows pressure in 5-10 seconds.

I'll post a video when I get'r back on the water.

-Adam

That makes me think you've got a bad oil pump on that engine. Either it's losing prime or the relief valve isn't sealing reliably.

 

[Nomad Willy]

C lectric,
Quite a project and I didn’t know you were that much of a gearhead.

 

[Lepke]

Everything I've read about engine wear indicates most wear happens at startup. But I don't think pre-oiling extends life on most engines. The engine with low pressure is already damaged. Probably limited to main and rod bearings if only run at idle with almost zero pressure. Bearings are easy to change.

To make a pre-oiler, use a hydraulic accumulator, or maybe a small water pressure tank would work. Once the accumulator is full, a solenoid valve opens at startup and allows the oil to pressurize the engine. With the engine running the accumulator is refilled and the valve closed. It can be setup with timed relays to control the valve at startup and refilling. The bladder side of the accumulator will have to be reset for lower oil pressure than pressure used in hydraulics to allow the lower engine oil pressure to fill it.

I used a portable accumulator on racing engines with a length of hose and self closing hydraulic fittings, no valves. I connected the tank, after the engine was pressurized, started it. After the engine was up to temp, disconnected the accumulator.

 

[rslifkin]

Everything I've read about engine wear indicates most wear happens at startup. But I don't think pre-oiling extends life on most engines.

That's my understanding of it as well. Startup wear is the worst, but the components that a pre-oiler protects are rarely the first to wear out. So in practice it doesn't often extend engine life.

 

[jleonard]

You might try raising the idle by 50 rpm or so and see if pressure comes up quicker.

 

[C lectric]

You might try raising the idle by 50 rpm or so and see if pressure comes up quicker.

That is a good suggestion. Often oil pressure can be low because the engine is not idling at the spec. rpm. 50 revs more should help.

 

[AdamC]

That is a good suggestion. Often oil pressure can be low because the engine is not idling at the spec. rpm. 50 revs more should help.

Roger that. Raising RPM a little does seem to help but I always wonder if that does more harm than good. This is my 3rd season with the boat and both engines seem to be running smooth and strong at about the 3000 hour mark. The PO (original) claims that he's observed similar behavior on both engines during the years he owned. I've never seen it on the stbd engine.

The pressure is not low on the port engine. It always comes up to normal (25-40 psi at idle depending on temp) and matches the stbd. It just seems to take too long. I can't understand how a bad oil pump could do that so I'm assuming is some sort of "losing prime" situation but I don't know how I could verify that.

Incidentally, I note that my engines (4LHA-STE) have two oil pumps with two separate oil pickup tubes. It seems they both discharge to the same place (jacket-water/oil heat exchanger) one through an internal passage and one through an external oil pipe run around the outside of the engine. I've never even heard of that. Anybody know why? What does "SUB" mean as in OIL PUMP (SUB) on the diagram.



Thanks Again,
-Adam

 

[Clark]

As the PO of Adam's boat for 18 years, I always used the Jay Leonard approach and lifted the RPMs a bit. This would bring the gauges right up and also trigger the alternators to charge. If engines were off for more than about 3 days, I also followed the stop switch pre-lube as specified in some manual.


I just called a friend with basically the same engines and his gauges are faster to come up but can still take maybe 5 seconds or so delay for the slower of his two engines. I note that he lives in FL and runs his boat at least once every week so not much opportunity to settle and no winter storage. I've asked him for more information next time he's on his boat and will let you know if I hear back.


There should be two pressure sensors, one for the pressure gauge and one for the switch for the buzzer. Which one did you pull and install your manual pressure gauge in? It would be interesting to compare the cold start results between the two senders with your manual gauge. Does the buzzer go off about the same time as the gauge goes up or does one lead or lag the other?


Someone (Mac Boring, Larry Berlin?) once told me the gauge was installed in a narrow passage and it could take a while for it to clear out whatever settled there and for the oil to flow. Maybe a smart gearhead that has had a 4LHA-STE apart can confirm this. I think they were suggesting there was flow before the guage was actually registering pressure. Have you noticed any change in the sound of that engine between start and when the gauge goes up? When I change the oil and filters, on first start of the engine, it is noticeably noisier and it is very obvious when the oil begins flowing as it quiets right down. I've never noticed this sound difference between startup and when the gauge begins to read.


I heard from Larry Berlin that the oil filters have check valves in them to prevent the oil from draining back and this is why he didn't not recommend ever using anything other than Yanmar brand oil filters. If there is a bad check valve then I would expect the delay would resolve with the next filter change which was not my experience.


Adam, when you had the sender out to put the manual gauge in, have you tried looking/checking/cleaning whatever is behind the hole of the sender? Maybe check both the gauge sender and the switch sender ports. I've never removed them to have a look.

 

[Arc]

For most engines you do not need more then 5psi at idle rpm so there is a lot of leeway when often engine have 20 psi. or more