MEP-002A control panel relay failed? Any thoughts?

[jacobsk]

I've been digging through the TM's and reading old posts but haven't found anything specifically addressing an issue I have with my most recent MEP-002a.

The shut off solenoid had been unbolted from its location (thankfully still present) when I purchased the generator, and after cleaning the fuel system I've come to find there is no voltage getting to the fuel shutoff solenoid.

The hour meter on the panel, voltage gauge on the panel, and auxiliary fuel pump do not function (may or may not be relevant), and when I turn the rotary start switch to "preheat" there is no usual click nor the traditional dimming of the panel lights signifying that the relay is functioning and providing power to the glow plugs. Upon checking for voltage to the glow plugs there is none. I wonder if I have a bad rotary start switch?

The thing that gets me is the guys at the auction site were able to get the generator running with the fuel shutoff solenoid removed, which leads me to believe it's not an oil pressure switch issue. I suppose they could have gotten it going with the fuel shutoff solenoid removed and plenty of cranking though.

I get plenty of white smoke while cranking, good 35ish psi of oil pressure, and the governor linkage moves freely.

Anyone got any ideas? Thanks for the help.

 

[jacobsk]

I should mention that I have function checked the fuel shutoff solenoid by jumping two wires to the batteries and it is working. The click I'm referencing in the original post is the one heard when turning the switch to preheat. In this case I hear nothing.

 

[ClintA]

I bet it is the switch, I got a unit that the screw was out on a wire on switch (glow plugs) it looked like it was there but was not, I am not saying you did not look, but they might be loose? Good luck, I hope you get her going.

 

[jacobsk]

Well tonight after some monkeying around with the starter rotary switch, basically unscrewing each lead and re tightening the screws.

The relay now engages for the glow plugs, and the generator actually roared to life unexpectedly when I turned the switch to run on accident!

I let her run for a little while, just long enough to find that no gauges work on the control box, making me wonder if I have an issue with a bad ground or something. Anyone expierience something similar?

 

[ClintA]

Did you check for voltage even if your gauges were not working? If not next time you start unit check and see if your getting anything anywhere, It could be that your voltage regulator is not working?

 

[jamawieb]

Well tonight after some monkeying around with the starter rotary switch, basically unscrewing each lead and re tightening the screws.

The relay now engages for the glow plugs, and the generator actually roared to life unexpectedly when I turned the switch to run on accident!

I let her run for a little while, just long enough to find that no gauges work on the control box, making me wonder if I have an issue with a bad ground or something. Anyone experience something similar?

I had one that did the same thing, it turned out to be the ground on the control box. The ground is on the bottom of the box and attaches to the frame.

 

[jacobsk]

Thank you both for the ideas, I will start my search with the ground area under the control box and then switch my attention over to the voltage regulator if necessary.

I appreciate your ideas!

 

[jacobsk]

Well today was spend mostly on fuel system cleansing, removing the fuel tank, using some gravel to get the usual quarter inch of crud out of the bottom of the tank, removing the orange varnished diesel, flushing the lines, and replacing the filters.

I also removed the heavily corroded ground strap from the underside of the control box (wowsa) and cleaned everything there up.

Picked up two 1/4 inch bolts to reinstall the fuel shut off solenoid, which was a pain in the butt to do due to the close quarters and fuel lines, but got it done none the less. Even managed to drop one of the bolts down into the blower shroud (doh!) and had to fish it out with the little fishing tool.

Just before dark I gave it some fresh fuel, and went to start it up. Fuel shutoff solenoid is functioning properly now and with the preheat she started easily in the 70 degree weather.

The oil pressure gauge pegged and the unit would not stay running, so I may have a situation where there is too much oil in the generator (haven't changed it yet as I haven't gotten around to it) as well as a faulty oil pressure switch.

First thing tomorrow I'll change the oil, filter and jump the oil pressure switch to see if that keeps her running.

Another interesting thing about this 002A is it must have had a throttle control cable from an 003A installed when it was overhauled back in 2005. The cable has extra length creating a large "U" behind the fuel filters and causing rubbing on the cable conduit along the edge of the blower shroud above the oil pressure gauge.

While I was momentarily trying to start the unit, holding the switch to start and watching the oil pressure needle dive hard to the right I did notice the frequency meter hunting, and the voltage gauge operating, so at least the control box seems to have some life in it.

Also realized that the auxiliary fuel pump does not operate even though it appears to be new. The "square box thing" (forgive me but it's after midnight here and I can't remember the name at the moment) mounted on the fuel pump wire wire is pretty corroded so hopefully if I cut that out of the equation the pump will function.

I knew sooner or later, at the prices I'm willing to pay for these generators, that I'd end up with one requiring more than an oil change and fuel cleanse to get it running. I admire those of you who have the patience and ability to completely overhaul these machines . Hopefully I'm headed in the same direction.

This generator came mounted to another M116A2 trailer with a canopy that conveniently had every seam separated. I have to admit that when I realized I had a pile of 5 separate canopy pieces rather than a good serviceable cover I got excited thinking to myself "I bet there are a bunch of folks on SS who've been waiting for an accurate set of M116A2 canopy dimensions!" Before I get it sewn back together I'll make sure I get the dimensions off each piece and post them up for those of you looking to have a canopy sourced for your M116A2 trailers.

 

[jamawieb]

Sounds like it's coming together nicely. The oil pressure gauge maxing out on start up is normal, after a few minutes it will lower to 30-40lbs. But you need to check the oil level and make sure it's not overfilled.
Since it will not stay running, it sounds like the oil pressure switch is malfunctioning. So I think you are on the right track with jumping the oil pressure switch.
Generators like these, really make you appreciate the ones that only require cleaning and fluids.

 

[Chainbreaker]

M116a2 Canopy Cover

This generator came mounted to another M116A2 trailer with a canopy that conveniently had every seam separated. I have to admit that when I realized I had a pile of 5 separate canopy pieces rather than a good serviceable cover I got excited thinking to myself "I bet there are a bunch of folks on SS who've been waiting for an accurate set of M116A2 canopy dimensions!" Before I get it sewn back together I'll make sure I get the dimensions off each piece and post them up for those of you looking to have a canopy sourced for your M116A2 trailers.

I would be very interested in obtaining those dimensions! My #2 genset is on a M116A2 and just has a tarp across the bows for now. It would be cool if someone with a CAD drawing package could then use your dimensions to create a downloadable/printable CAD fabrication drawing file. I would like to be able to take a dimensioned dwg to a place that works with canvas (or some kind of industrial truck tarp type of vinyl material) to get an OEM style cover manufactured. I did find a place on eBay that can make a mil spec. canvas one but the $1,000 price tag + shipping seemed a bit stiff. I'm really surprised that someone hasn't come up with a way to make a bunch up and sell them at an affordable price. You sure see a lot of M116A2's advertised with just the bows and no cover so there has to be a market for these covers. I'm hoping to be able to have one made with quality canvas, or better material, in the ~$500 ballpark.

 

[jacobsk]

Well I started the unit this afternoon after jumping the oil pressure switch. The unit doesn't stay running so something other than the switch must be causing the fuel shut off solenoid to cut out after the start switch leaves the start position.

While it was running (with me holding the start switch) I played with the throttle cable to try and dial in 60hz. The unit just didn't sound like it was at full RPM. Something just wasn't right and I didn't want to run it long not knowing what faults the engine has.

I removed the blower shroud and found the throttle linkage bent to the rear. No wonderwhy the throttle adjustment is maxed out. Does this lever look bent to anyone else? I don't want to go straightening it out before making sure it's not just some strange Onan stamping with a twist!

 

[Chainbreaker]

There is also a temperature sensor under the shroud where the ventilation louvers are that will cause it to not stay running if defective. Try jumpering that one and see if it makes any difference. Could be a loose connection there or a bad sensor switch. If memory serves me right, I think you can remove just the shroud covering the exhaust muffler and there is just enough room just below it to clip on an alligator clip type jumper across the terminals without removing the whole ventilation louver assembly.

The throttle linkage is a perfect 90 without any twist. So yes yours appears to be a bit tweaked. Seems odd that it could have been bent that way during normal use but who knows what these units have been subjected to before we got them.

 

[jacobsk]

Thanks for the confirmation on the bent throttle linkage. I'll straighten it out.

I currently have the exhaust louver box unbolted with the blower shroud being removed so I'll try jumping it to see if that helps.

In other news my start rotary switch seems to be jammed now. It only allows temporary rotation to preheat and no longer turns clockwise past off. Glad that failed now rather than when the unit is all cleaned up and running!

 

[Ray70]

Where was the throttle when you took the pictures? The arm isn't touching the stop screw, so if you were maxed out on your cable you might be able to adjust the cable ( unless it's already at the end of the thread ) to get more travel. Straightening out that arm will also give you more travel, unless the arm is touching the high speed stop screw before you get up to 60HZ. Once you get the arm/cable adjustment and running issue sorted out you might also need to mess around with the spring to get the droop adjusted properly.

 

[jacobsk]

Ray, the throttle cable is indeed out of thread at this point. I'll get the bracket straightened out and reset the governor linkage per the TM to make sure everything is squared away. Right now the engine never gets to 60Hz so I presume someone just kept pulling on the cable trying to get more out of it. That or someone tried to start the machine using the throttle cable as a recoil starter

Tonight I cracked open the rotary start switch to see if I could diagnose the issue. It looks like one of the leads generated an arc and melted causing the switch to fail. Part of me thinks this was a result of foolishly spraying electronics cleaner in the switch and attempting to start the unit before the cleaner had an opportunity to completely dry. Chalk this one up as a $85 learning experience... Fortunately William over at Delks has rotary switches available!

 

[jacobsk]

A Picture of the insides of the start switch. The two Red arrows are pointing to a broken off lead and a badly bent lead. The pink arrow is pointing to a blob of melted metal which was at one time part of one of the leads.

I presume that with wet electronics cleaner still in the switch an arc jumped when I tried to start the unit. This melted one of the leads and either welded them together damaging them or the blob became loose from the arc. Either way the switch stopped rotating clockwise once I tried starting it after spraying cleaner inside. probably because the blob or bent lead created a physical block inhibiting rotation.

Notice the center gray polymer cylinder is also cracked. I believe this was from before I killed the switch with cleaner. Before it's demise the switch felt like it had excessive play and wouldn't always make a solid connection when turned turned.