MEP 002A entering periodic runaway condition

[OG]

I have a MEP002A with ~1300hrs on it. It has been running good for quite some time. Few months ago, I have noticed a strange sound coming from it (from a distance of about 400ft through thick forest) and when I run to it (would take me 20-30 seconds), it would run normally, but there was a lot of white smoke around it. I thought maybe water in fuel. I drained, cleaned and replaced all filters and fuel tank, changed oil and refilled with fresh fuel. After that event, it run into runaway one more time, white smoke billowing, and I was close so I shut it off. Curiously, I could not restart it. Solenoid clicks but starter does not turn. Next morning, it started fine, like nothing happened.

Just today I was working close to it, running it with no load, and after maybe an hour, it entered into runaway with obviously high RPMs. These were higher then what I can achieve with a gas knob pulled out to the max. Ultra-thick white smoke was billowing from exhaust.
Frequency gage was pegged to 65, load gage for which I thought it was broken since I got a generator, as it was never operating, was showing life showing ~25% load. I did not turn it off, but rather reduced the gas, and frequency dropped to 55 Hz, smoke stopped. I then pulled gas knob back to adjust to 60Hz and everything was working fine for another 20 or so minutes when I decided to shut it off. Again, I could not restart it after shutting it off. Solenoid clicks but starter does not turn. I turned the crankshaft by hand, and it turns, so engine is not seized.

I am sure tomorrow morning it will start again like nothing happened. The air temperature was around 50F, but I noticed that louvers were completely shut off after running at no load for about an hour.
I could open them by hand, they are spring loaded, but they do appear to move. Any ideas of what could be happening? Your help is appreciated.

Thank you

OG

 

[Scoobyshep]

Key takeaways: it over reved and you could reduce throttle manually. this tells me that the linkage isnt binding at the IP (common issue). This leads me to 2 thoughts. Governor or IP. The ip can be knocked out of time and still run. It would run like crap and need more throttle to run the correct speed then when the pump jumps back in time it would surge. I personally have never opened a governor on these sets so i cant provide much guidance on it.

Things to look at: on the IP on the bottom there is a nub on the casting, Is there a screw there?

i would check the engine timing. theres a procedure in the TM to do a flow test to see if the port is closing at the correct time.


NO crank issue: meter the solenoid wire on the starter. if it gets 24v when in start and the starter isnt turning its likely a bad solenoid or starter. you really dont want to diagnose this by ear because theres a couple of things that make a healthy clunk when activated. so use a meter and be sure.

louvers not opening. This comes down to how hot the engine got. normally im not running one of these sets at a low load so i cant say for sure how much they would open i do know at rated load they seem open within 10~ 15 min (based on my observation).

 

[OG]

OK, so here is an update. It appears that fuel is somehow getting into the oil. On the order of 2 qt. per 10 hrs of running. When I first observed the problem genset was due for maintenance and I replaced the oil among other things. What struck me is that much more than 3 qts came out. And oil was liquidy much more then expected.
I just dumped the oil again, after 10 hrs of running, and there were solid 5 qts of "oil" which came out. Liquidy, of course. Given the quantity, I have hard time to believe it is coming through rings. The only other way fuel can get into crankcase is through IP. Pump is delivering what it needs to deliver to cylinders just fine, but it appears equal amount is squeezing into the crankcase. The whole thing is running fine, no smoke of any kind in exhaust, clearly both cylinders are firing just fine. So, I need to dive into pump, there is gotta be some seal somewhere which pretty much disintegrated?
Starter issue is not clear, so far, could be a separate issue. As long as I do not go through "smoke event" starter appears to work fine. No issues with shutting the engine and starting it again.

 

[Scoobyshep]

if you are getting fuel in the oil, the IP is the place to look.

The big thing here is what pump is there. there are 2 flavors and one is repairable, the other when they fail make a great doorstop. since repair parts are pretty unobtainable for the doorstop, i cant tell you if seals are available either.

feel under the pump theres a nub in the casting if theres a screw there its a doorstop.



since you are on the path of taking the IP off do yourself a favor, on the left side of the ip theres a small screw. remove it and stick the ass end of a 1\8 drill bit in there then as you apply gentle pressure to the bit have someone SLOWLY rotate the engine when the bit drops in you should be on the timing mark

 

[OG]

 

[OG]

Looks like no screw at the bottom. I was not aware of variations in M50 pump. What do I need for a repair? Looking at GMG site, a gasket kit and I may as well replace a plunger guide? Thank you for a timing tip!

 

[Ray70]

Say a prayer for having an Ambac pump!
I don't know of anything inside the pump that could allow fuel into the oil except perhaps the flat rubber square cut ring that seals the pump unit to the aluminum housing, #42 in the parts diagram if you look in the TM section.
As far as rebuild parts about all you need is that flat seal and the o-ring ( # 29 ) that seals the top of the pump unit to the aluminum housing.
Ambac sells individual parts as well as small kits, but last I knew they did not sell to the end user so you may need to look on-line.
Go to the TM section for the 002 and on the 2nd page you can find all the Ambac info including rebuild instruction and the PN's for the seals in question.
If you have difficulty finding it, say something and we can point you to it.

MEP-002A, 5KW, Air Cooled Generator Manuals and additional Information

Here are the Technical Manuals needed for the MEP-002A air cooled 2 cylinder generator For those who do not know about how the Army TM's are laid out: 1. LO is the Lubrication order. It tells you when, how and with what, about how to service the Equipment. 2. TM is for Technical Manuals 3. TM's...

steelsoldiers.com

 

[Scoobyshep]

100% good deal here. If it were me i would rebuild the pump (they are fairly easy). When ordering parts a wise man would also order a plunger guide, by your description of how its running it wouldnt surprise me if it was fractured.


Another pro tip: Get a 12point 5/8 socket (youll need one anyway) and remove that cap(big cap in the center not the 5/8s, this ones bigger), under it is the 5/8s 12pt. its torqued fairly high and its easier to crack it on the block vs in a vice.

 

[Ray70]

Agreed! Big cap is 1", smaller one inside is 5/8" 12 pt. Loosen before removing the pump.
Read ALL the info available in the TM section regarding the pump removal procedure.
Do not pay any attention to the instruction in the TM as far as pump rebuild, go by the Ambac documents, the TM tells you how to rebuild the American Bosch PSU pump not the M-50.
Good advice on the plunger guide, for $30 it's worth having on hand even if you don't need it now.
also, if mounting it in a vice, ONLY pinch it by the mounting flange thickness, or put the 5/8" 12pt. delivery valve holder and the 1" big cap back on loosely and hold the 1" cap in the vice. Never clamp sideways on the body of mounting flange.... ask how I know.....
You will need to make yourself a modified C-clamp / socket or tube device to compress the spring and allow you access to pick out the two 1/2 circle retailer clips. There are discussions about that on the forum, but essentially a large c-clamp with a 5/8" deep socket with an opening cut down the side can become your new best friend here.
You DO not need item #35 , the super expensive tiny plastic delivery valve spacer! it is completely unnecessary even if yours is deteriorated or missing completely. it only helps keep things positioned while you reassemble the delivery valve holder IF the pump is mounted sideways on the motor. it is unnecessary when rebuilding it on a bench.
Lastly you can read up on the many many post showing how to rebuild the IP.
It's very easy once you understand how it comes apart and the tricks to get it back together.
1 last note: To access the 2 seals in question you don't need to disassemble the spring, timing button or any of the slightly more complicated stuff, just the throttle unit and the 4 cap screws holding the pump body into the housing. But to access the plunger guide you will have to dig all the way into the IP.
Read up first and ask questions if you get in trouble... DON'T guess at it and risk damaging the IP.

 

[LuckeyD]

As you rebuild this check the TM in the Tech Manual section. There are buttons in there to set the pump pressure so you do not overdrive the injectors. The injectors are a great place to see if one is not closing right putting fuel in the oil. I used to set these at 1750 cracking pressure on the 9DJCs in NATO. The manual says the cracking pressure and you may observe the pattern and any after drip. Better place to start than the pump.