Perkins 4-108

[bob24]

Hi;
Have a rebuilt Perkins 4-108 with about 400hrs on it and yesterday on the SC ICW the alarm went off. Had less than 10lbs oil pressure on the gage and the oil pressure alarm was going off too. Each has it's own sending unit. Anybody got any ideas. Thanks, Bob

[FAST FRED]

BOTH ! engines went to 10psi at the same time?

Look for a poor ground in the gage circuit.

If only one , inspect the oil , and do a oil filter change .


Let us know,

FF

[bob24]

Hi Fred;
I didn't make myself clear. Have one engine and 2 sending units. Did an oil change and had no effect. Thanks for you input. Bob

[FAST FRED]

Sounds like you lost a bearing. IF you can find an oil line (pump to filter?) you could measure the pressure there WITH A MECHANICAL GAGE! to see if its the oil pump output , or an internal fault.

The oil pump it self is very reliable , But?

FF

[bilgeboy]

I caught your drift.

You are reasonably sure the oil pressure is low because the alarm circuit tripped AS WELL AS the pressure sending unit reading low. This is what you meant by “both.” You now think the drop in oil pressure is real because it was confirmed by redundant, independent circuits.

I think you are right. You have a real drop in oil pressure. You did exactly what any boat owner should do…an oil change. This lets you inspect the oil as well as make sure that the pressure is not low due to low oil levels. I’m with you so far. You trust your gauge, so you are ready to make more interventions and then restart, judging success by the installed instrumentation.

I have to sit back and watch, now. I like diesels, and like learning more about them, so all I can add is that I will read your thread with interest…and if the diesel gods allow, try some reading on the subject.

Please post your findings so that we can all learn something,

Thanks,

Mike

[bilgeboy]

You didn't mention if you changed the oil filter as well...I assumed you did but you know what happens when we do that.

I did get a chance to review the subject a bit. It looks like you need to make sure the oil pump is turning with the engine. The key or splines or whatever mechanism communicates the oil pump shaft to the gears (the "pump") themselves could be chewed up. Other than that, the sump pick-up needs to be checked out.

Not a whole lot to go wrong.

Please fill us in on your progress.

Mike

[Frosty]

Recently overhauled?????

A failed pump would be zero pressure.

Under 10?? check the pressure relief valve is not stuck open.

It will be wide open at cold but if it stays open pressure will drop right off.

Or youv'e turned a bearing.

[bob24]

Hi Folks;
Here is my friends update on his 4-108.
For those mechanics/engineers out there, our problem turned out to be a sheared bolt for the idler pulley gear hub in the timing gear circuit; this loosened the retaining plate which relieved pressure from the oil channel which fed from the main oil gallery. Apparently, no further damage was done to the engine. This is surprising, given that the timing gears were loose and could have led to interference of the pistons and valves, and no oil was reaching the rocker arms which could have seized the rockers or the valves.
Who would have guessed. Thanks for your response.

Bob

[Frosty]

Who found that? the guy that overhauled the engine.

[FAST FRED]

our problem turned out to be a sheared bolt for the idler pulley gear hub in the timing gear circuit

Sounds like the "rebuilder" did not own , or understand the use of a Torque wrench.

FF