Runaway MEP-003a !!!

[Guyfang]

We normally just took off the air filter housing and kept a clip board handy.

 

[rickf]

Most Detroits came with them, the only problem is that by the time the engine wore to the point of actually needing it the damper was frozen with rust.

 

[Fireriders]

Your right about the other fuel sourse. The CO2 extingisher is a great idea. I think I will add it to my truck ASAP. CO2 does not support combustion and with the air intake on the fender it's easy to get to. Thanks for the info.

 

[rickf]

To all those considering a Co2 extinguisher keep in mind that you need one big enough to fog that intake until the motor has completely stopped. On a genset with that very heavy rotating mass that could take a while. If you run out of Co2 before the engine stops turning it will pick right up where it left off. Keep that board ready. LOL.

 

[Tinstar]

Will be keeping a block of wood on the generator trailer now after reading this thread.

 

[Guyfang]

I have never seen that happen. Mostly, repeated painting causes the linkage to "Freeze Up", or it simply falls apart. The Ball joints are the real trouble spots. Dirt and paint cover them and they can not function as they were supposed to. And last but not least, not adjusted right/adjusted until they break.

 

[Chainbreaker]

Haven't made much progress taking anything apart to dive deeper by inspecting/scoping engine internals due to cold rainy weather lately. Though having had more time to think about it... I'm beginning to suspect the runaway engine events are pointing more & more to worn cylinders/rings & that hot oil vapor blowby is fueling the over-speed runaway engine events.

Here's why I'm leaning that direction:

1. After I changed out the oil, I ran it enough to refill all the oil passages & oil filter and I let it sit overnight. Checking the cold engine the next day it showed as ~1/8th inch above the dipstick full mark... I remember thinking to myself "close enough".

2. I recall that during the last 10kw load test I looked at the Hz meter & noticed Hz meter showed during the latter part of that run that it had increased from 60 Hz to ~67 Hz & I had to dial the throttle cable back to 60 Hz & it seemed slow to respond to the throttle adjustment to get it down to 60 Hz again.

3. Now after checking the oil level, since it has sat a few days since last run, I noticed oil level is down ~ 1/2" below full dipstick level reading.

4. The hard shiny black ~1/8" deposits inside the exhaust ends I noticed after my post purchase inspection could be due to burning oil vapors mixed with diesel leading to that type of black hard shiny exhaust combustion deposits.

So... it appears that while running genset under varying electrical loads (load testing resulting in hot engine/hot oil) the engine runaways that I have experienced could be due to hot oil vapor blowby which correlates with the very thick pitch-black smoke out exhaust during the runaway engine events.

So now I believe the only way to confirm or eliminate that possibility is to get the injectors pulled & run a compression test as well as using my endoscope to look inside the cylinders to look for scoring etc.

 

[Tinstar]

Could the engine be coked up a bit?

Not knowing its history, I would run it at almost full or at full load for hours to burn off any deposits, some of which could be making the rings stick.
Seafoam can also be added to oil to clean internals.

The coating on the exhaust sounds like it wasn’t worked very hard for extended periods.

 

[rickf]

Have you checked the vapor return for blowby? That would be a sure indicator of ring condition. A lot of blowby means worn rings. And on an air cooled engine there is little to no wet stacking due to the higher head temperatures. If you have no oil leaks the loss of oil would also point in that direction.

 

[Ray70]

I'm not 100% sure, but IIRC, I don't think you can see directly into the cylinder bore very well from the injector hole.
The heads are a pre-chamber design where the injector and glow plug go into a small pocket connected to the cylinder, not into a wide open cylinder bore per-se. I think there's a hole in the center of the chamber connecting to the main bore, but it's pretty small, not even sure if a 5mm bore scope will fit.
I can check tonight, I've got a head on the shelf with the injectors out.

 

[Scoobyshep]

I'm not 100% sure, but IIRC, I don't think you can see directly into the cylinder bore very well from the injector hole.
The heads are a pre-chamber design where the injector and glow plug go into a small pocket connected to the cylinder, not into a wide open cylinder bore per-se. I think there's a hole in the center of the chamber connecting to the main bore, but it's pretty small, not even sure if a 5mm bore scope will fit.
I can check tonight, I've got a head on the shelf with the injectors out.

I can tell you that my scope was too wide to make it to the cylinder

 

[Chainbreaker]

Could the engine be coked up a bit?

The coating on the exhaust sounds like it wasn’t worked very hard for extended periods.

Not knowing its history, I would run it at almost full or at full load for hours to burn off any deposits, some of which could be making the rings stick.
Seafoam can also be added to oil to clean internals.

Yes, it very well could be coked up. Engine hours are unknown. Actual genset usage is unknown. The replacement Control Panel (a MEP-002 take-off box) that was on it when I purchased it showed 2800 hrs. The original Control Panel box that came with the MEP-003 hours is unknown. So actual run time hours are a mystery as well as the history of gensets usage... other than what the seller told me that it was used 4 years ago on the farm due to forest fire taking out power for some time. So, in the case of a long-term power outage it very well could have "loafed along" when there were no heavy AC demands imposed on it.

I have run it hard but not long enough yet due to the run-away engine situation. I bought a Comfort Zone Garage Heater a 10,000 watt unit (I already had a 5,000 watt unit for exercising my MEP-002a's) however this run-away engine situation is interfering with running it long term under heavy loads other than the ~ 1/2 hr or so under varying loads 5kw-10kw that I have managed to run so far.

 

[Chainbreaker]

Have you checked the vapor return for blowby? That would be a sure indicator of ring condition. A lot of blowby means worn rings. And on an air cooled engine there is little to no wet stacking due to the higher head temperatures. If you have no oil leaks the loss of oil would also point in that direction.

I would tend to agree... I've looked for a Vapor Return line/cannister (-24p manual doesn't identify one) so not sure where to look...?

 

[Rodburner]

New here and new to mep003s. I just finished putting a piston in mine. Would there be a chance the oil could be getting past the valve stem? Intake valve stem seal leaking? I’m not a mechanic so this is more of a question of it being a possibility?
Gary

 

[rickf]

The valve guides would have to be worn pretty bad to have any runaway issue from that. And there is really not enough oil in the top end even if they were. But why just one piston? Did you check the rest of the engine while you were in there?

 

[Chainbreaker]

New here and new to mep003s. I just finished putting a piston in mine. Would there be a chance the oil could be getting past the valve stem? Intake valve stem seal leaking? I’m not a mechanic so this is more of a question of it being a possibility?
Gary

First off... welcome aboard! You've found and landed at a great forum & you will find it to be a great resource with an impressive membership of subscribers/contributors!

Yep, there's certainly more than one path for oil to end up in the combustion chamber vaporizing & ending up as added fuel. Since this unit came to me with virtually no history, I'm going to start with the easiest stuff first to check out and work my way through until I find a definitive answer for the hot engine runaways.

Unfortunately, my "Compound to-do list" seems to only be getting longer as the weather worsens... limiting working much on it outside. Right now, its pouring hard rain, or as the local TV Weather guy calls it, an "atmospheric river" this evening with snow in the upper elevations!

Also, don't hesitate to start a "New Thread" should you have any specific questions that are particular to your -003a unit. It can get confusing if there were multiple member's with gensets looking for troubleshooting assistance all in same thread. However, if experiencing an identical or similar issue... it might make sense due to situational similarities.

 

[Rodburner]

Yes to those suggestions. Definitely a great site to learn from and be a part of. Started my own thread for the generator I’m working on. Always better to let folks to help the original poster and start another thread with its specific situations. Since nobody suggested valve guides I thought I’d bring it up. Might be very unlikely. I don’t have a lot of experience with diesel engines.
Good luck and keep checking in to see what happens. Thanks

 

[rickf]

Diesel engines are still an internal combustion engine so all of the same principles still exist. The differences are instead of spark to ignite the fuel you have the heat frim high compression and the throttle is controlled solely by the amount of fuel added. This is where a runaway can come into the picture if unmetered fuel is added. But the basics of fuel, compression and spark, in this case ignition heat, still pertain.

 

[Rodburner]

rickf, didn’t mean for my comments to sound like I hadn’t read your post, sorry. Since you explained how guides wouldn’t allow enough oil into chambers, I just let the suggestion be ruled out. My follow up post should have reflected that better. My post also meant to say “I’ll be checking in on this thread “ but what I thought I typed and what showed up was different.
I hope you read my thread that sort of explains the piston situation (not well enough), didn’t want to derail this thread. On that note, I felt I should explain what I did wrong in the thread it happened. Hope you can forgive my errors. Thanks

 

[rickf]

No problem, After I posted the first attempt I reread you post and and figured it out. I think you may have seen that post of mine before I deleted it and posted what is there now. I am not saying the valve route is impossible but if the valve guides are that bad it is probably not going to have enough compression to run due to burnt valves.