MCII MEP-805B

[MRAD338]

Good Morning,

I purchased an 805B gen set and have a question. It starts and runs great, has 13 hours on it but it shows no oil pressure when running, no rpm's either. It will not generate power though, I can only assume that the computer has an interlock to prevent the generator from loading up the engine in a no oil pressure event. Can anyone shed some light on this?

 

[Chainbreaker]

Since no one has responded yet I will chime in. First thing is you should download all the TM's located here.

I don't think your assumption is valid regarding the computer allowing the generator to run w/o oil pressure with no load. Every modern Military diesel generator should not allow the engine to start & "continue to run" w/o oil pressure. Without oil pressure to lubricate the engine it will be damaged, even without a load, in a matter of minutes.

Since you are not displaying RPM's or OIL pressure on the display it would seem that there's either a DC power issue somewhere in the instrumentation not allowing those readings to display - the senders for those readings or in the display itself.

Not producing power is probably not related to your instrumentation readout issues and will need separate troubleshooting. Hopefully its something simple.

Since I'm not at all familiar with these newer models (804/805 series gensets) that is literally just my 2 cents worth.

I'm sure one of the SS members with knowledge of these newer digital computerized units will offer some better troubleshooting. In the meantime, please read the TM's and get familiar with them so their advice is easier to process and more beneficial in expediting the diagnosis.

 

[Guyfang]

Assuming gets you in trouble ever time. As Chainbreaker said, RTB. This gen set requires you to KNOW about the set, before stating it. The first thing you need to do after reading the Operators TM, is to then open the control panel, (and I would also take the control panel top off) and all the doors. Then start unplugging and re-plugging up all connectors. Look for loose and or disconnected wires/cables/plugs. This series set is world renown for loose everything.

No military gen set will allow you to start AND run, without oil pressure. Yes, start up will occur. But as soon as you let the S1 go, the engine will stop. Its possible to also start the set and engage the S7. But then a LOP light warning should appear.

If the battery's are not in tip top condition, often problems like this occur. Also, if you do not hold S1 up long enough, this kind of thing will happen.

 

[mciikurzroot]

Good Morning,

I purchased an 805B gen set and have a question. It starts and runs great, has 13 hours on it but it shows no oil pressure when running, no rpm's either. It will not generate power though, I can only assume that the computer has an interlock to prevent the generator from loading up the engine in a no oil pressure event. Can anyone shed some light on this?

Chain Breaker is giving you good advice, and for the sake of moving forward, lets assume you have oil in the system and its really making oil pressure, oil pressure failure is damn near a thing of the past, but the computer thinks you don't have it, so as quick as you can, after the set starts, turn on BATTLE SHORT, this should trick the safety and interlocks and hopefully make power, but its a poor fix, and really just one to make you feel better, but its not a long term or desired fix, IF it works..

These sets don't have the typical patterns or ckts to trace out where it takes you to a logical fix ... Most often when these sets start to puke up fixes are not easy or economical, we never took any position except time and parts [money] were not to be an issue.. But that was in 96' you got a ragged out if you're lucky WIN 7 based CIM computer, WIN2000 or Vista most were built around, so even WIN7 is 12 years old, so you figure out your real reliability forecast as a gen set or door stop, Hour meter means nothing, it's the CIM that is the core of it all.

good luck and keep us informed... mac/mc

 

[mciikurzroot]

Chain Breaker is giving you good advice, and for the sake of moving forward, lets assume you have oil in the system and its really making oil pressure, oil pressure failure is damn near a thing of the past, but the computer thinks you don't have it, so as quick as you can, after the set starts, turn on BATTLE SHORT, this should trick the safety and interlocks and hopefully make power, but its a poor fix, and really just one to make you feel better, but its not a long term or desired fix, IF it works..

These sets don't have the typical patterns or ckts to trace out where it takes you to a logical fix ... Most often when these sets start to puke up fixes are not easy or economical, we never took any position except time and parts [money] were not to be an issue.. But that was in 96' you got a ragged out if you're lucky WIN 7 based CIM computer, WIN2000 or Vista most were built around, so even WIN7 is 12 years old, so you figure out your real reliability forecast as a gen set or door stop, Hour meter means nothing, it's the CIM that is the core of it all.

good luck and keep us informed... mac/mc

I omitted, the oil sender unit is not likely a culprit, we chose those while a bit of odd value 24vdc and 1-5 volt output, we took Deere's total experience and used every accessory they recommended, so the core package is totally solid and Deere has no plans to stop using that engine , in fact they have a full ELECTRONIC same engine all CAN Bus controlled, you can stand a Nickle up on the valve cover as it ramps up to speed and it won't fall.. I'm off your topic, but you see my point i hope... mm

 

[MRAD338]

Guys, Thanks for all the info. I've read the TM's til I'm blue in the face, I wish I had the wiring diagram then I would have a better starting point. Oh, thanks for being positive and not throwing me under the bus for being new to this equipment. When you have a machine shop full of CNC's in the middle of BFE you learn to fix a lot of stuff, I don't give up easy.

 

[Guyfang]

Wire diagrams in the TM. Wire diagrams on the door of the set.

Open up the control panel door. and take a picture of the relays. A good picture.

 

[mciikurzroot]

As Guy sez the very explicit wiring schematic is on one door and a detailed flow diagram is on the smaller door.. Every wire and function is identified you will have no real issues following them, each wire has a starting and ending letter, the wire numbers always start with 3 numerical numbers immediately followed with a letter until the 27th letter then AA will follow the best my memory the 805/6 don't have these double letters. when A ends at any location but proceeds on the wire number will remain the same but the trailing letter will be B.. B will make one stop and end, then C will follow, you get the idea D e F g H blah blah.. Switches are numbered as S? but the switch also has terminal numbers embossed on the switch body near the screw head.. make it run.. mac/mc

 

[mciikurzroot]

Something else, take the schematics off the doors, 1/8 aluminum rivet is all, mount emm on come coroplasts [Campaign signs] yard signs use white latex caulking or what ever color as a glue, cut the coroplasts to fit near same size, this way you hold the damn thing and not always have to run back to the door and stoop over to read the schematic.. or take em to your copy shop and make paper copies and glue emm on the coroplast..FYI the 805/6 schematics are near identical, dont get hung up on the small few differences, either one will work no real differences.. mac/mc