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oiling onan oil pressure

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20 replies to this topic

#1 Toolpartzman OFFLINE  

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Posted June 12, 2012 - 07:07 PM

So, you have a twin cylinder engine with a poor (Historically) pressure lube pump system in need of rebuild.This is an old style, no oil filter engine with only a tapped port for a gauge.

SO you decide to install ONLY an external lube pump and flow the oil backwards through the engine-(with higher oil flow and pressure).!

WILL IT WORK ??? Or will you fry your new rebuild??? OPINIONS WANTED so :

"let 'er fly, boys" :blowingup:

Edited by Toolpartzman, June 12, 2012 - 07:20 PM.


#2 KennyP ONLINE  

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Posted June 12, 2012 - 07:31 PM

I'm not that 'couragious' of a thinker. Haven't been there nor done that!
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#3 MH81 ONLINE  

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Posted June 12, 2012 - 07:37 PM

What make of engine are we looking at? An exploded view may shed some light on pros & cons.
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#4 MH81 ONLINE  

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Posted June 12, 2012 - 07:38 PM

Never mind, I see ONAN as a tag... Sorry.

That's an engine I've never even turned a wrench on...
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#5 Texas Deere and Horse OFFLINE  

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Posted June 12, 2012 - 07:43 PM

My question to you is, why not replace the oil pump and the internal lube line that goes across the block to the other side to lube the crank bearing on that side. These engines ran for over a 1000+ hrs with no issues if you kept the oil changed regularly.
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#6 Alc ONLINE  

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Posted June 12, 2012 - 09:02 PM

Just wondering is it just " your " engine or all this model engine have low oil pressure ? And how much lower is it then factory spec's ? Al

#7 olcowhand OFFLINE  

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Posted June 12, 2012 - 09:53 PM

Could just be a weak pressure regulator spring, or damaged control pin. Need to know the model.

#8 Bruce Dorsi ONLINE  

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Posted June 12, 2012 - 09:56 PM

I believe it is possible, if done correctly.

If you are removing the existing internal pump, the pressure port inside the block (where the pump discharge was connected) will need to be plugged, if you plan to apply presurized oil through the external gauge port.

If you plan on keeping the original oil pump in place, your plan may work. ....If the original pump is a positive-displacement pump, backflow to the sump should be minimal or none at all. .....A lot depends on the type of existing pump, and if a pressure relief or pressure regulating device is incorporated in the pump.
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#9 Toolpartzman OFFLINE  

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Posted June 13, 2012 - 05:21 AM

Actually my question was more theoretical. However my old B43 Onan is a good example. It, along with some others used no filter. An external pump would allow for a filter, and added reservoir capacity if needed. The more I think about it, as long as your new pump discharge point is in the pressurized portion of the circuit, the direction of flow should be the same

#10 Toolpartzman OFFLINE  

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Posted June 13, 2012 - 05:25 AM

Never mind, I see ONAN as a tag... Sorry.

That's an engine I've never even turned a wrench on...

I'm beginning to wish I HADN"T :bounce:

#11 Toolpartzman OFFLINE  

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Posted June 13, 2012 - 05:31 AM

Could just be a weak pressure regulator spring, or damaged control pin. Need to know the model.

Daniel, I think perhaps this was common for these early twin Onans, and keeping proper oil levels was critical. This engine shows evidence of oil starvation and at $120 for a new oil pump, I'm wondering about a better solution.

#12 Toolpartzman OFFLINE  

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Posted June 13, 2012 - 05:36 AM

My question to you is, why not replace the oil pump and the internal lube line that goes across the block to the other side to lube the crank bearing on that side. These engines ran for over a 1000+ hrs with no issues if you kept the oil changed regularly.

I've have to look, but I didn't see a replaceable line. If I build this engine though, I'll expect far more than 1000 hrs out of it .

#13 KennyP ONLINE  

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Posted June 13, 2012 - 05:56 AM

My Onan has an oil filter. Never been inside it yet, but I plan to pull the heads before long. I want to see if it is a 16HP or 18HP.
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#14 olcowhand OFFLINE  

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Posted June 13, 2012 - 08:35 AM

Where your oil pressure line hooks up.....does the line go to a plate with 2 bolts? If so, you remove the plate & replace with a filter mount. I've added oil filters to a few older Onan engines. Even without the plate, if a hole is drilled in the proper place for oil return, and holes drilled & tapped for the filter mount, one can add a filter to any Onan.

#15 olcowhand OFFLINE  

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Posted June 13, 2012 - 08:47 AM

But to answer your original question, YES, one could put on an external pump. The regulating valve is between the pump & the oil gauge pressure port. The way the oil flows through this valve, it would not work as a regulating valve with oil coming the opposite way, so the external pump would have to have a regulator on it.





Also tagged with one or more of these keywords: oiling, onan, oil pressure

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