Runaway MEP-003a !!!

[Chainbreaker]

I finally found a MEP-003a 10kw unit to add to augment my MEP-002a herd that was close enough for a 1/2 day recovery drive. I need 10kw capability to run AC unit during any hot summer day outages... We been lucky with summer outages occurring during reasonable summer temperatures so far...

First some background info...sorry a bit long bear with me... there is a critical mystery issue: The MEP-003a I located off Craigslist hadn't been run for 4 years since it was last used during a long-extended power outage by the owner. Owner said it had been kept under cover since then & it had not been started since & had dead batteries. I took 2 charged batteries with me intending to test start it but when I looked in the fuel tank I decided not to as fuel looked bad... a bit cloudy & inside tank was heavily rusted appearing to have accumulated humidity/water in fuel system (casualty of Oregon high humidity wet winters). I chose not to test run it for fear of passing bad fuel further towards injection pump & injectors.

Anyway, my initial visual inspection of this unit told me it was worth more than the asking price (even if by chance it might not initially run for me) since it appeared solid & in good shape & it included a custom-built small trailer it was mounted on. The one odd thing was that it had a "MEP-002a instrument control box" mounted on it showing 2800 hrs. (so no idea if that was a used box or new box with zero hrs. on Hobbs meter? Thats not counting X hours on original MEP-003a box's Hobbs meter. I figured that the original MEP-003a console box on it, somewhere along the line, needed replacing (the owner didn't even know his unit was a 10kw unit as he had it advertised as 5kw thinking it was a 5kw MEP-002a unit due to the MEP-002a placard on control box ). Looking at the pictures in ad I could see it was clearly a MEP-003a unit. However, I have no idea how many actual hours it had accumulated. Anyway, I decided to take a chance & purchased & put it on my car hauler trailer & took it home.

After getting home I performed a more detailed visual inspection & everything checked out to my close inspection except to having one bad glow plug lead broken off which I would replace later & I noticed quite a bit of shiny carbon build up inside the 2 exhaust pipe outlets (appeared to be about 1/8th inch). I took off the original yucky fuel tank & put a shiny new "never used" MEP-002a smaller fuel tank on it & filled about 1/2 full of diesel just for an eventual test run. Before even attempting a start I completely serviced the entire fuel filtering system. Water separator was a mess with a layer of gunky fuel inside. Though as I went on to the other fuel filters it got better with the last filter nearest IJ pump looking like it had decent fuel in it. I thoroughly cleaned (used some Acetone to cut the gunk) and replaced all fuel filters checked oil level. Before I started it, I opened the control box and cleaned & worked all the switches with DeOxit Gold contact cleaner. I then did a first start attempt & it came roaring to life! Initially the stone-cold engine blew a bit of white smoke upon start up until it cleared out & was running steady but with some blue smoke that eventually dissipated as it came up to operating temp for the most part. I powered a light off the convenience outlet & it was producing electricity.

Now for the looming issue: I then proceeded to do an initial 5kw load test to check out electrical AC power output. It pulled 5kw nicely (still had the blue smoke on start-up) so I got engine up to temperature & ran it for ~15 minutes so I could do an oil change. I drained oil it looked pretty bad like it hadn't been changed for a long while. So, I decide to put in some Shell 15/40 oil I had on hand just to do another run up to temp & flush oil again. Everything was running great under another 5-kw load for ~15 minutes so I dropped the load and with no load with me just about ready to shut it down it suddenly took off as in run-away diesel engine! Started revving up blowing black smoke out the exhausts as I was scrambling to shut it down by turning it off. It was not shutting down very quickly as my heart was racing wondering if I was going to see pistons coming out the top of engine! I then pulled the emergency shut off switch & it slowly shut down. All in all, since I was near the control box it maybe ran 10-15 seconds in run-away mode blowing black smoke. I inspected engine let it cool down for a few hours and ran it again & nothing happened ran just fine for over half an hour under varying 5kw & below loads. Not wanting to push my luck I called it a day!

So, the next day I decided to go ahead & change oil & filter & put in some Delvac Syn 15/40 oil & new filter for its final oil service with some of the HotShot oil additive to help clean any buildup that might be causing the blue smoke on start-up (stuck rings, carboned cylinders, etc). I ran it unloaded & on start-up it again blew some blue smoke which dissipated mostly after it warmed up & it ran great with very little noticeable smoke other than typical diesel exhaust. I then decided to run it with my 10-kw load tester (mobile Comfort Zone Garage Heater). Worked it up to the 10kw load & it performed nicely. Did several cycles of no load and partial load to full 10 kw load & it passed the test over the course of about 1 hour . Decided to call it good and let it idle down to cool off a bit before doing a shut down. As I walked up to Control Box with no AC load on it engine started another runaway event racing engine blowing black smoke, I quickly pulled the emergency shut down panel breaker & it slowly shut down. I raised the engine cowling cover above the the fuel filter side & noticed that the valve cover nearest the Control box appeared hot & smoking a bit. Hmmm, not being familiar with run-away diesel engines where do I start with troubleshooting? What would cause this type of air-cooled engine to take off & rev up faster & faster until it begins to blow black smoke?

My thoughts are:

1. Bad injector(s) as in sticking, or pop off pressure needing calibration, or replacement? I think I might have a new injector or part of one in my spare parts stash...
2. Perhaps blue smoke on start-up is a sign of low compression (unknown hrs on engine) perhaps with hot oil blow by acting as additional unmetered fuel?
3. ???

 

[Scoobyshep]

Take this with a grain of salt as I am an electrician, but things that need checked:

Sticking throttle linkage\govoner
I'd start here as it sounds like as the units loaded it's compensating (as it should) the under load reduction it's not decreasing. When you pulled the emergency stop (should also in off) the shutdown solenoid is pushing the IP closed slowly.

Sluggish solenoid
The shutdown solenoid is not extending fast enough (this wouldn't cause a runaway by itself but it's good to ensure it's moving freely and has enough extend spring force)


Worn rings
The only actual runaway event I've witnessed was due to a very worn engine and it was running away off of the crank case oil.


This is why you should have a CO2 fire extinguisher at the ready. This is very useful in stalling an engine that can't be shutdown under normal means

 

[glcaines]

You mentioned that you let the engine idle down to cool it. You can do real damage if you idle the engine on either an MEP002A or an MEP003A gen set. You should never ever let one idle. Shut it down at full speed / 60 Hz.

 

[2Pbfeet]

@Chainbreaker nice score! I hope that you get this diagnosed. I would be leaning towards anything that might be sticking from the IP to the solenoid, with a focus on the governor and the solenoid. Fuel shutdown solenoids generally act in a second, or perhaps two. Given that you had to use acetone in the places that you already looked, I would be tempted to keep cleaning the fuel system, and make sure that the fuel solenoid works well.
When you step loads down, does the frequency stay steady?
Was the temperature OK?

And +1 on the CO2 extinguisher from @Scoobyshep.

You mentioned that you let the engine idle down to cool it. You can do real damage if you idle the engine on either an MEP002A or an MEP003A gen set. You should never ever let one idle. Shut it down at full speed / 60 Hz.

I agree, although I wonder if the OP (@Chainbreaker) meant "idle" in the sense of "no load".

All the best,

2Pbfeet

 

[rickf]

A diesel will only run away due to extra fuel. This can be in the form of actual fuel or engine oil. Turbocharged engines have the problem a lot when the oil seals in the turbo go out and it feed unregulated motor oil into the engine. with a non turbo engine I guess it could happen from oil getting past the rings but blowby on and engine that bad would be very noticeable. I do not even know where the crankcase breather is on an 002/003.

 

[Scoobyshep]

The key phrase that set me off was removed load and it ran away. Telling me that the throttle was open more than no load speed. If the governor or linkage was sticky it would seem to surge and runoff

 

[G744]

The black smoke is indicating full rail on the fuel, normal for that condition.

White smoke usually occurs with a cold Diesel.

Blue smoke indicates burning a little oil, should dissipate when up to temp.

 

[Chainbreaker]

Take this with a grain of salt as I am an electrician, but things that need checked:

Sticking throttle linkage\govoner
I'd start here as it sounds like as the units loaded it's compensating (as it should) the under load reduction it's not decreasing. When you pulled the emergency stop (should also in off) the shutdown solenoid is pushing the IP closed slowly.

Sluggish solenoid
The shutdown solenoid is not extending fast enough (this wouldn't cause a runaway by itself but it's good to ensure it's moving freely and has enough extend spring force)

Worn rings
The only actual runaway event I've witnessed was due to a very worn engine and it was running away off of the crank case oil.

This is why you should have a CO2 fire extinguisher at the ready. This is very useful in stalling an engine that can't be shutdown under normal means

Yep, it responds well to varying loads and the solenoid appears to be working ok & the governor spring setting seems to be in the right position. I'll recheck the solenoid's "spring force" somehow... compare to spring force on my -002a units for comparison.

Worn rings come to my mind as well, especially since I don't have a true Hobbs hour reading. What seems odd is that both times it ran away it was not under any load. However, if there is no load to utilize the fuel I can see where a no AC load might cause over fueling off hot crankcase blow-by fumes escaping past rings.

Great tip on having a CO2 available! I had 2 ABC extinguishers nearby but don't have a CO2, going to get one now!

 

[Chainbreaker]

You mentioned that you let the engine idle down to cool it. You can do real damage if you idle the engine on either an MEP002A or an MEP003A gen set. You should never ever let one idle. Shut it down at full speed / 60 Hz.

Yeah, not idling per se... I meant the governor reacting to "no AC load & still at 60 Hz" without any throttle adjustment.

 

[Scoobyshep]

Yep, it responds well to varying loads and the solenoid appears to be working ok & the governor spring setting seems to be in the right position. I'll recheck the solenoid's "spring force" somehow... compare to spring force on my -002a units for comparison.

Worn rings come to my mind as well, especially since I don't have a true Hobbs hour reading. What seems odd is that both times it ran away it was not under any load. However, if there is no load to utilize the fuel I can see where a no AC load might cause over fueling off hot crankcase blow-by fumes escaping past rings.

Great tip on having a CO2 available! I had 2 ABC extinguishers nearby but don't have a CO2, going to get one now!

Abc has sodium bicarbonate so big mess. CO2 is clean and starve the oxygen enough to stall. I have used nitrogen as well to accomplish the same thing

 

[Chainbreaker]

@Chainbreaker nice score! I hope that you get this diagnosed. I would be leaning towards anything that might be sticking from the IP to the solenoid, with a focus on the governor and the solenoid. Fuel shutdown solenoids generally act in a second, or perhaps two. Given that you had to use acetone in the places that you already looked, I would be tempted to keep cleaning the fuel system, and make sure that the fuel solenoid works well.
When you step loads down, does the frequency stay steady?
Was the temperature OK?

And +1 on the CO2 extinguisher from @Scoobyshep.


I agree, although I wonder if the OP (@Chainbreaker) meant "idle" in the sense of "no load".

All the best,

2Pbfeet

Regarding the keeping up with additional fuel system cleaning... I forgot to mention I put in a full can of Seafoam as well as Optilube XPD with maybe a gallon or two of diesel for its first run to make sure there was some cleaning solvent type action & lube working through IJ pump & injectors.

 

[Chainbreaker]

The key phrase that set me off was removed load and it ran away. Telling me that the throttle was open more than no load speed. If the governor or linkage was sticky it would seem to surge and runoff

I would tend to agree in that scenario, however I didn't explain accurately that when load was removed it reacted to load drop (breaker off) & appeared to be maintaining 60 Hz with no load. It ran with no load during what I call a cool down phase for maybe 2-3 minutes before it suddenly increased RPM and ran away.

It seems to run away with a very sudden & deliberate increase in RPM to the point of blowing black smoke out the exhausts. In my "panicked state of mind" I wasn't able to calmly assess the exact state of things... however I think I noticed "black exhaust" starting in the exhaust nearest the control box and then the other exhaust started emitting black smoke (delayed a bit). But I couldn't calmly troubleshoot the situation as all I could do was focus on getting it quickly shutdown.

FWIW...Its worth mentioning again that when I raised the engine shroud cover that the valve cover nearest the control panel was smoking a bit like it had overheated... Maybe that is pointing to having a bad cylinder.... ( broken/worn ring or...?) I think @Ray had a source/method for building a DIY compression tester

 

[Chainbreaker]

The black smoke is indicating full rail on the fuel, normal for that condition.

White smoke usually occurs with a cold Diesel.

Blue smoke indicates burning a little oil, should dissipate when up to temp.

Are you saying that because its "dark black smoke" billowing out of exhausts that it's not due to hot oil vapors combining with no load fueling? In other words, if it were getting a lot of hot oil vapor blow-by smoke past rings it would tend to be more bluish color as in less black?

 

[2Pbfeet]

As a generator with a previously unknown history, I would not worry much about a starting haze, at least until the overspeed issue has been sorted out.

Overfueling runs hand in hand with high exhaust temperatures in my experience. If you can, I would check the cold start to warm exhaust temperatures on the manifold to see if you have a hot or cold cylinder.

Is it possible that there is an air leak in a fuel lines somewhere, i.e. getting air in the lines, or possibly an air leak on the fuel filters, and that it opens up under heat?

All the best,

2Pbfeet

 

[rickf]

Air in the lines would do just to opposite, It would stumble and stall. Black smoke indicates fuel but I have to wonder about that concoction you put in the tank. It has run enough of that through to clean it out so I would get rid of that and go with straight diesel. That stuff was a lot of solvents and little lubrication. Also take the air cleaner off and have a board you can slap on that hose to plug it off. This is a much better way to kill the engine than C02 which will cause thermal shock to valves and pistons. If it runs away and you are able to close off the air then it does not matter what the switch state is, no air it will die. This way you are not depending on a switch which only shuts off the diesel. It will have no effect if the fuel is motor oil, the air dam will shut it down no matter what.

 

[Guyfang]

It would have been nice if you had been able to LOOK at the Fuel shut off solenoid, when this was going on. Because it MIGHT be going north, and causing the over speed problem. The solenoid arm is supposed to be spring loaded. The ball joints are supposed to move easy. I have seen instances where the bottom ball joint was bend, and it hung the arm up and it would not stop the gen set when it was turned off. This is something easy to check, and then if its good, you have one less thing to think about/check. Then I think I would pull the preheaters or injectors out and use a bore scope to take a look see.

 

[2Pbfeet]

Air in the lines would do just to opposite, It would stumble and stall. Black smoke indicates fuel but I have to wonder about that concoction you put in the tank. It has run enough of that through to clean it out so I would get rid of that and go with straight diesel. That stuff was a lot of solvents and little lubrication. Also take the air cleaner off and have a board you can slap on that hose to plug it off. This is a much better way to kill the engine than C02 which will cause thermal shock to valves and pistons. If it runs away and you are able to close off the air then it does not matter what the switch state is, no air it will die. This way you are not depending on a switch which only shuts off the diesel. It will have no effect if the fuel is motor oil, the air dam will shut it down no matter what.

Sometimes, yes, sometimes no. Air in the injector lines causes the pressure to be lower than specified and I have seen injectors that then weep larger amounts of fuel. BTDT. Just something to be aware of as a possibility. I have no hands on experience with the MEP-006A engines at all.

All the best,

2Pbfeet

 

[Chainbreaker]

As a generator with a previously unknown history, I would not worry much about a starting haze, at least until the overspeed issue has been sorted out.

Overfueling runs hand in hand with high exhaust temperatures in my experience. If you can, I would check the cold start to warm exhaust temperatures on the manifold to see if you have a hot or cold cylinder.

Is it possible that there is an air leak in a fuel lines somewhere, i.e. getting air in the lines, or possibly an air leak on the fuel filters, and that it opens up under heat?

All the best,

2Pbfeet

Great recommendations. I'm making my next "startup troubleshoot ck list" & I will definitely check exhausts ports upon next start up to see if there is an issue with coming up to temp on each cylinder's exhaust manifold. I haven't observed any leaks in any fuel lines into/out of injection pump nor any going to injectors.

By the way, I did have a very small leak on one fuel filter's housing after I changed the filters. I tightened it up before last restart and it still drips a tad now & then. I wasn't too concerned because I do intend to change it out to the "spin on adapters" from @Ray70. Don't want to commit to changing out the filter mounts to $pin-ons until I've verified that I've got a solid reliable genset on my hands that I can trust my house's electrical system to utilize during any summer outages with AC on.

Fortunately, I've got all Winter/Spring to sort this genset out before it might be needed during hot summer months with AC on. However, right now I'm juggling lots of priority tasks on the compound... though I do plan to take my time sorting out this generator & do it thoroughly so I can trust it to perform reliably. In the meantime, the -002s units can carry any winter/spring loads during an outage. Fortunately, I've got the "2 is 1, 1 is none" very well covered 5kw genset-wise during winter/spring since we utilize a 1,000 gal propane tank for whole house heating & hot water heater (no electrical air-conditioning until summer).

 

[Chainbreaker]

It would have been nice if you had been able to LOOK at the Fuel shut off solenoid, when this was going on. Because it MIGHT be going north, and causing the over speed problem. The solenoid arm is supposed to be spring loaded. The ball joints are supposed to move easy. I have seen instances where the bottom ball joint was bend, and it hung the arm up and it would not stop the gen set when it was turned off. This is something easy to check, and then if its good, you have one less thing to think about/check. Then I think I would pull the preheaters or injectors out and use a bore scope to take a look see.

Thanks for pointing me to those areas, I will perform a "close inspection" of the fuel shut off solenoid & linkage for binding/hang ups etc. before next start-up & make sure it's up to snuff. I do have one of those lighted iPhone "endoscopes" that's pretty handy. When I replaced the 1 damaged glow plug (broken tab) I did try to insert endoscope in that hole but it wouldn't go in much, too small a hole. I'll try the preheater and/or injector route as those are larger diameter.

 

[Chainbreaker]

Air in the lines would do just to opposite, It would stumble and stall. Black smoke indicates fuel but I have to wonder about that concoction you put in the tank. It has run enough of that through to clean it out so I would get rid of that and go with straight diesel. That stuff was a lot of solvents and little lubrication. Also take the air cleaner off and have a board you can slap on that hose to plug it off. This is a much better way to kill the engine than C02 which will cause thermal shock to valves and pistons. If it runs away and you are able to close off the air then it does not matter what the switch state is, no air it will die. This way you are not depending on a switch which only shuts off the diesel. It will have no effect if the fuel is motor oil, the air dam will shut it down no matter what.

Seafoam can be used at "100% undiluted strength" with no damage according to the mfg. I've heard of others filling the last fuel filter cannister with straight Seafoam. The XPD does provide added lubricity in addition to cleaning according to mfg. So, with it mixed with fresh Diesel, I don't think it would reduce lubricity to the point of causing any harm. The reason I decided to use this mixture was because of the state of the diesel fuel that had set in the fuel tank for 4 yrs and sat in filters (with some gunk in water separator & adjacent filter) & same fuel sitting in injection pump. However as noted, last filter before IJ pump looked pretty good before servicing it with acetone flush cleanout & new filter).

Also due to the shiny black deposits about 1/8th" I noticed in both exhausts' pipes exiting mufflers I wanted to use Seafoam in hopes of getting engine hot under varying loads & burning off any potential deposits in cylinders/rings due to not knowing history of whether it was adequately exercised/loaded when put to use during the extended outage it was reported to have been used for... over 4 yrs ago.

I do plan to add more diesel to tank and not add any additional additives for now since tank is close to getting empty. Fuel system should be good to go with having performed complete filter changes & manual use of Acetone to clean out/rinse gunk in filter housings plus the Seafoam/XPD treatment with fresh diesel run through it all with loads applied. Also, ambient air temps when running under load were in the mid 60s to 70's. So being an air-cooled engine it should have been happy at those temps.