ChangFa Diesel engine low oil psi shutdown?

Yea, how do you stop your engine now? What exactly happens when you decide "it is time to stop the engine"? You probably press some button or pull some lever, and then what happens?

Try here- good stuff.

I use an FW Murphy solenoid to control my Onan DJE diesel:

Are you being a smart ass??? or am I reading your words incorrectly?

Let me explain how my engine has the speed lever set, you slide the lever down and tighten a knob (twisting) that passes through the lever. If I was NOT present to monitor the oil pressure and needed to shut it down to prevent damage to engine, who would turn this knob to release the lever? You?

This is why I was asking on how to go about doing this task? What method would do the job and what parts could be used?

Thanks for your input.

That is a pretty crude mechanism. Cutting off fuel to the fuel pump may take a minute to shut the engine down, which seems too long. You need to modify this speed control mechanism so it doesn't require tightening knobs. Probably the best, if this engine is manually started, is to use a solenoid that will hold the speed lever in the right position when the juice is on, and drop it when power is cut off. Wire an oil pressure switch with normally closed contacts (normal in this case taken to mean oil pressure OK) in series with the solenoid and battery. After starting the engine and developing normal oil pressure, you pull the lever to operating speed and the solenoid holds it. If the solenoid burns out, the battery goes dead, a wire falls off from vibration, etc. the engine will be shut down. You could wire a normally closed push button in series with the rest of the parts as a manual shutdown switch, so you don't have to overpower the solenoid to shut it off.

If this engine has an idle position to the speed lever, you have to make sure a spring or whatever pulls it all the way to the shutdown position on oil pressure failure.

Jon

you are reading my words incorrectly. The reason why I asked you how you stop your engine now, is that the automatic stop mechanism would need to do a similar thing to what you do manually. For example, when I want to stop my onan DJE, I disengage the switch that supplies electricity to the holding coil of the fuel shutoff solenoid.

That releases the solenoid, makes the solenoid push on the fuel control lever, which shuts down fuel. The engine stops in 2 or so seconds. Hence, automatic shutdown mechanism is doing the same thing, namely, interrupts electricity to the holding coil.

If your stopping mechanism is different, then you would need a different solution.

To know what method would do the job, it is important to know how the job is done manually.

Jon,

This is a great flow of idea that haven't crossed my mind! I thank you for the input and have something to work with now.

Then, let me apologize for any remarks that I wrote in regards to your response. I'll post some pictures of the speed control on my engine tomorrow.

Thanks.

Very gentlemanly of you to offer your apology. Ignoramus12712 is one of the more polite people on the board and has shown very nice manners and appreciates all concepts offered.

Harold

Indeed. I think the problem is, the issue being discussed is reasonably complicated so that it requires a first-principles approach.

This means asking specific questions that make no assumptions at all. Unfortunately this sometimes makes the question asker seem totally retarded.

I understand this effect well because I do it a lot at work.

Sometimes the only way to "get to the bottom of it" is to look like a total retard. :^)

Jim

To stop a diesel you don't need to shut down the fuel, merely stop the air flow. Worked for the diesel gen sets I ran in Vietnam and works for an emergency shutdown for the 8V-92 Detroit in the bus here on campus. Merely rig a flapper over the air intake (needs to be a positive seal) that is spring loaded to close, use a solenoid to keep the trip mechanism armed until oil pressure falls below a preset point, then trip and let the flap stop all air.

You can buy a oil pressure guage with adjustable stop point so that you stop at some point before zero pressure is reached. Avoid oil starvation damage that way.

Georg V.

Yeah, but that's about the worst way to shut it down. The flap is for killing a runaway engine, which is one of the charming properties of Detroits.. Each time you use it you have to manually reset it (as it's set up on the Detroit anyway, but you could set one up that resets itself) and you'll put a lot of fuel in the oil doing it too.

John

Most of the 6-71 GM diesels that drove the smaller drilling rigs had air shut of butterflies on the air intake manifolds. This was so that they could be shut down even if natural gas came into the air intakes insufficient quantities to keep it running if the fuel was shut off. It was an important safety feature in the event of a blow out. Apparently, it was as a result of a case where the diesels were shut off during a blow out and didn't stop until a con rod came out of the side of the crankcase and the ensuing sparks sent the whole lot up .

Regards

Tom

What you said is right on the mark, but wasn't the OP worried about shutting down in the case of oil pressure loss?? That doesn't happen unless something has gone badly awry and in my mind at least that calls for stopping motion as quickly as possible to minimize damage. You wouldn't want an automatic restart condition, rather you would want to determine the cause and correct before a restart. And oil loss would cause me to want to drain and check the lower end, if not more.

George V.

Ah, true. Somehow I took your original statement as a suggestion to use this as a regular method of killing the engine. If set up with care, such as ensuring that the crankcase vent wouldn't allow the engine to continue running, it would likely work well.

John

No problem. I am interested in how your engine can be shut down in case of emergency.

Thank you for your kind words.

Yep. I think that an approach of "let's figure out how a job is done manually, and see if we can do the same thing automatically", is a great first thing to try.

My pleasure.. In my opinion, you have earned them.

Harold