low oil pressure

Boston · Mar 18, 2011

no worries
I was just trying to throw out some ideas

pink scar?
that bad eh
try vitamin E on it and maybe it will go away

glad the tank turned out
does it hold fuel

Adler · Mar 19, 2011

kcmd said: ↑

Thank you for your help . I have fresh water cooled with a sea water jabsco pump feeding the heat exchanger.

Dear kcmd,

I'm sorry for my delay respond , I was abroad.
First you didn't answer me regarding the asked question, if your engine is equipped with Oil / Fresh Water heat exchanger.
All the Original Marine Diesel Engines are equipped with some kind of Oil Heat Exchanger. The main reason is to hold the Oil temperature not higher than 40°C more to the compared Soft Water's Temperature value.
Consequently to that the Oil's Temperature , even in the worst conditions of any short period malfunction, never exceeds to 130°C which actually affects to reduce extremely the Oil's viscosity and finally to start decompose its Lubrication ability. On such kind of operational conditions is observed as consequence a Low Value of Oil Pressure .
It is important to be mentioned, that in Diesel Engines the Oil's Flow way next to the Lubrication process,is to return into the Oil Sump passing through the tolerances of journal bearings (Main / Crankshaft bearings - Crank pin Bearings - Con rod Bearings - Thrust Bearings - Turbo Charger bearings - Cam Shaft bearings) ,through the tolerances between Liners / Pistons and Valves / Valves' Guides and (depending the designer) from the Oil injectors which lubricate the lower face of Pistons.

Based on this fact you have to understand that the Oil Pressure Value is depended to:

1. Oil Flow that the Oil Pump produces -( dV/dt V=Volume t= time ).

2. Size keeping of the above mentioned tolerances.

3. Oil Viscosity and Oil Temperature as interactive coefficients.

4. Any leakage on the Lub Oil Circuit.

5. Any working irregularity to the Oil Pump and/or Circuit - Assistant - Valves.

Usually the manufacturers install three Assistant Oil valves:

1. One double Pressure Throttle & Relief Valve direct next to the Oil Pump that keeps the pressure on standard level into the Oil Pump's Pressure side to avoid cavitation phenomenon in the Pump housing and to protect the circuit from high pressure shocks. This valve is inside the Oil Sump.

2. One by Pass Flow Valve which secures and ensures that the flow will not be interrupted if the Oil Filters will be blocked for any reason. This valve is built in the Oil Filters Base.

3. One Pressure regulated - Electric Contacts Valve (like the one which described 1n the attached file, as an example ) which has regulated by the manufacturers to define the upper and lower value of the Oil Pressure corresponding to enable or to disable the Red Light and Sound Alarm. The Operation Idea of this Valve is based to enable the Red Light and Sound Alarm on a Pressure Value X and to disable them only if the Oil pressure increases to a higher value X+d than the one was enabled them.

According that the Valve has two regulation Screws:

1. One which regulates the Value of (X) that represents the ALARM Oil Pressure value. When the predefined value is reached the Red Light /Sound Alarm are enabled. This is a Nominal Variable (X) Adjustment

2. The other one which regulates the (d) factor that defines how much higher should be increased the Engine's Oil Pressure compared to Oil Pressure ALARM value, regarding to disable the enabled ALARM process.This is the Differential Variable (d) Adjustment.

May be all of that is too much for the case.
The above summarized description has the purpose to give you an answer on question "how is it works...?"

My advice regarding your case is to check your engine at the level and point that you can well understand, follow and apply the above notes for the specific technical subject.

Over that you have to look for a professional engineer with strong experience related to this type of engine and to proceed on a common annual survey as it is recommended from Service book of the engine's manufacturer..

Take a note when you search to find that kind of information in a marine forum - on best of the cases - few people will write you the precise theory which covers the issue you asked.

On the other hand the facts are:

1. You have the engine in your hands.

2. You described to all of us the symptoms and the issue which should be solved.

3. You will be the man who will cover the cost of the repairs.

4. I think also that you are the Captain of the boat.

and finally "as it well known on marine field" responsible, in any issue and the related decisions , is the man who pays.
This based on the fact that he chooses among the possible options and "he manages the money on his hands".

Anyway, I hope all these to be useful and helpful.
Click to expand...

Adler · Mar 19, 2011

Dear kcmd,

The attached file is here (by my mistake was not included into previous post)

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low oil pressure

Boston Previous Member

Adler Senior Member

Adler Senior Member

Attached Files:

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