MEP-802 excessive vibration?

[serial14]

I'm working on fixing a MEP-802. When running it, there seems to be excessive amount of vibration. The front gauge panel moves back and forth 1" and vibrates the wire harness enough that wires are breaking off things. When I look at the engine its self, that section of the generator doesn't seem to have much vibration. Its hard to inspect the generator head. But the control box certainly shakes a lot.

All panels were installed and closed except the top cover of the control section. That was taken off. The engine is basically brand new, so I did have to tear the unit fully down and rebuild it.
I know the 2 cylinder engine of the MEP-802 has more natural vibration than its larger siblings but what I'm experiencing seems excessive. Can anybody confirm this? Or give a better expectation of normal vs excessive?

From forum research I know that balancing the set really mean taking off the rotor and clocking it differently, hopefully fixing the imbalance. Is there anything else I should check? investigate? consider?

 

[Mattguy]

Here's a video of one of mine starting up.

 

[Ray70]

What are the chances that you can take a video of the suspect machine running?
Also, is the vibration the only known issue?
Have you load tested it to 100% output?
Does the exhaust run clean from about 0% to about 80%, then a little black smoke as you approach 100% load?
Excess vibration could also be caused by a cylinder imbalance due to a compression issue, leaking valves or fuel delivery imbalance as well as several other mechanical issues.
A little more performance data may help us narrow things down before you start taking things apart.

 

[Guyfang]

Do you have tops and maybe side pieces of the skin removed?

 

[serial14]

@Mattguy - thanks for the video. That is what I'm expecting to happen and have experienced previously in my professional life. Certainly not what my MEP is doing.

I can get some pictures and video posted later. But to answer some of the questions.

• All panels are on except for the top covering the control section. All doors are closed.
• I haven't gotten to load testing yet... still working towards that. Previous attempts at load testing showed I had a bad overload module. so that was just recently swapped. I was attempting another load test this past weekend
• Engine is a NOS spare from the military. its still in its "break in" time period actually. Starts up super easily even in cold temps( 30F ). No smoke. The couple times I have pulled some load, there is a small puff of black exhaust as the governor catches up and then it clears out. So the engine "appears" to be in fine shape.
• Vibration is the issue that always gets me due to wire breakage. It really likes breaking the wires going to the Emergency stop switch. Wire looming and spot ties are still all intact, its not like the wires are just free to move. . And its been present since I did the engine swap. Prior to the motor swap it didn't run at all due to a locked engine. ( See previous threads i started many years ago ). So now that I have a good engine, I'm working through all the other subsystems.

 

[Ray70]

All good info!
Without these details we would have assumed it was the original engine ( with unknown hours ) and that it was at one point working correctly.
Now we have better information.
Did you run into any issues with the flywheel , rotor plate fitment or the gen end cap / bearing when you swapped the motor?
I'm curious if it's an engine vibration or related to the generator
Does the TM mention anything about clocking the rotor for any reason? Or is there any data to support that theory, or was it just conversation here on the forum?

 

[serial14]

Rotor to Engine fitment is tight! See, https://steelsoldiers.com/threads/mep-802a-rotor-removal.167770/post-2044334 This is the same genset( I work on it every couple years ). That post was about separating the rotor from the locked engine. When I assembled it all back together( cleaning dirt and crud ) it was still a very tight fit. So I can't imagine there is any "center of rotation" alignment issues. I've read on other forum posts about clocking the rotor for potential improvements, I haven't done that step yet. The bearing in the rotor end cap was replaced with a brand new bearing.

 

[serial14]

Below is a picture of its panel configuration. I pull it out of the garage to run it.

I've seen in other threads the question "does it walk across the floor". As you can see its sitting on another 802 base with casters. Where I engine run is on a flat spot of the street. I don't need to lock the casters at all. And the base/casters have no visible vibration.

 

[serial14]

Here is a picture of the control panel marked up. The red arrow shows the direction of vibration. The "magnitude" of movement is 1". Meaning those gauges and emergency switch are moving 1".

The base of the control unit seems pretty stable. Its just the front control panel where its vibrating a lot and wires get broken. I realize the top panel probably mitigates the motion I'm experiencing. During the test run, I tried to use my body/arm to limit the motion and was unable to make a difference.

 

[DieselAddict]

Have you checked the exhaust temps for an imbalance between the cylinders?

 

[Guyfang]

And you had the same vibration with the top properly bolted on?

A video would help.

Are the vibration dampers, (Rubber Baby Buggy Bouncers) cracked? Tight? All the hardware there?

 

[Ray70]

I just re-read your previous thread where you disassembled the unit and I have a question on the rotor.
In the other thread you mention you took apart 2 machines, one came apart easily and the other ( this ) machine you had to fabricate a "Pusher" to jack the rotor plate out of the flywheel and in the process you started to bend the 2"x2" square tube puller.
My question is, did you use the "Stuck" rotor that you needed to pull off or did you reassemble this machine with the other rotor and stator that you removed easily?
Reason I ask is that if you had to apply enough pressure, with a bottle jack, to bend the 2"x2" square tube, I would not be at all surprised if you tweaked the thin, flat rotor mounting plate in the process.

 

[serial14]

@Guyfang - I checked the vibration pads. All hardware is present. All hardware is tight. The rubber isolation parts are what came from the unit from Govt Auction. So I can't claim knowledge if they are the proper 802 parts or from an 803. I've seen in other threads you talk about the difference. I can say the durometer of the engine mounts is softer than the generator mounts. The engine mounts i can push my finger nail into a bit. The generator ones I can't push my finger nail into. That being said... they don't feel/look like they are rotten solid pucks either.

I haven't run it with the top on in a very long time... mostly cause I was chasing issues with modules and wanted better access. I could try that for comparison

While inspecting the motor mounts, I did manually turn over the engine. No bad noises, scapes, etc.

@Ray70 - that is an excellent question... and I don't remember. I do recall in that original tear down, there was a generator housing that was cracked at all the mounts. And there was a rotor that was very rusted / corroded. And those came from different units, so I took the best housing and the "cleanest" rotor. I don't recall the details about "how hard" it was to remove the rotor I did use. As I think about what I just wrote, the best rotor came from the housing that was cracked at the mounts. That might be a bad clue? That unit was in pretty bad shape through out the whole tear down though.

The rotor I used was tested for shorts... no problems electrically. I also recall the rotor I used was a tight/precise fit when I installed it. Not a press fit, not a hammer fit . But "hand tightening" the bolts was needed to fully get the plate to seat against the fly wheel. We also tested that plate for "flatness" after all the "pusher tool" fun. And it was still flat/true as far as we could tell.


I appreciate all the supportive questions, its helping me work through stuff. My intention is to get it working enough to start again and take a video for you all. I realize and understand a 802 will vibrate more than a 803 and friends. But I've never seen mention of soo much vibration wires break off and kill the unit.

 

[Ray70]

You're correct about the vibration not normally breaking wires etc. they do vibrate, but they don't typically self destruct!

 

[Guyfang]

OK, Here goes. I have seen, bad vibrations because of:

1. IP's not adjusted right.
2. Engine damage.
3. Rubber Baby Buggy Bumpers cracked, broken, lose, improper hard ware, old style bumpers, (Different Material) and wrong bumpers.
4. Main Gen bearing bad.
5. Coupler out of balance, or misaligned between the Engine and Rotor.
6. Gen set box was lose.
7. Flywheel lose.
8. Coupler lose.

Some one once told me he had a bad vibration because the fan was on backwards. I never saw it, so would not claim that this is possible.

The parts you swapped back and forth, when changing the engine. Do you know for a fact, that those parts came from a MEP-802A? Not a MEP-813A? I know the flywheel is different. Don't think it could made to work between models. I never took a MEP-813A apart, so have no idea what the differences are. I remember when you did the swap. It took forty for ever's to get the darn thing apart. Now I had some that were a bit hard to separate, but never like you. I always wanted to look at everything you had there, just to figure out why it was so hard. Its simply puzzling, and maybe a clue here to this problem.

 

[serial14]

OK, Here goes. I have seen, bad vibrations because of:

1. IP's not adjusted right.
2. Engine damage.
3. Rubber Baby Buggy Bumpers cracked, broken, lose, improper hard ware, old style bumpers, (Different Material) and wrong bumpers.
4. Main Gen bearing bad.
5. Coupler out of balance, or misaligned between the Engine and Rotor
6. Gen set box was lose.
7. Flywheel lose.
8. Coupler lose.

Some one once told me he had a bad vibration because the fan was on backwards. I never saw it, so would not claim that this is possible.

The parts you swapped back and forth, when changing the engine. Do you know for a fact, that those parts came from a MEP-802A? Not a MEP-813A? I know the flywheel is different. Don't think it could made to work between models. I never took a MEP-813A apart, so have no idea what the differences are. I remember when you did the swap. It took forty for ever's to get the darn thing apart. Now I had some that were a bit hard to separate, but never like you. I always wanted to look at everything you had there, just to figure out why it was so hard. Its simply puzzling, and maybe a clue here to this problem.

Clarifying questions

#1 - I saw this mentioned in another thread. What sort of symptoms would lead me to check this?
#3 - Are you talking about the engine mounts and generator case mounts here?
#4 - Of the engine or the rotor end cap?
#5 - When I pulled it appart, I never really saw what I'd call a coupler. Just a flat plate between the rotor and fly wheel. Fly wheel was then bolted directly to the crank. What part is the "coupler"

I'm aware that a 802 and 813 both exist. And I'm darn sure that I had two 802s.

 

[Daybreak]

Remove it, and set it on the ground.
I had a MEP-802A sitting on a pallet in the back of a truck after coming home with it. It bounced and rattled the lifting eyes. Sounded like someone ringing bells.
Set it on the ground, problem solved.

 

[Guyfang]

Clarifying questions

#1 - I saw this mentioned in another thread. What sort of symptoms would lead me to check this? (Vibration can come, when the IP's are sending different amounts of fuel to the jugs. you can measure the temperature of the exhaust ports, to see if the temps are about the same.)
#3 - Are you talking about the engine mounts and generator case mounts here? (Roger)
#4 - Of the engine or the rotor end cap? (End Cap)
#5 - When I pulled it appart, I never really saw what I'd call a coupler. Just a flat plate, (Thats the coupler) between the rotor and fly wheel. Fly wheel was then bolted directly to the crank. What part is the "coupler"

I'm aware that a 802 and 813 both exist. And I'm darn sure that I had two 802s.

 

[serial14]

I got some time to work on the MEP today. Fixed up the wiring terminals that broke and added some additional spot time to help with vibration in those areas. Finally, I had some time to do an engine run.

With all the processing YouTube does during the upload process, the videos lost the high FPS fidelity showing the vibration. As you'll quickly see, it looks like the MEP is doing the wave everywhere. When I compare the YouTube result to my original videos, I would say the overall magnitude of movement shown on Youtube matches what I see in real life.

Given everybody's comments and hints I did the following tests during the engine run and made several observations.

• I saw the comments about putting it down on solid ground. I have many blessings in life and I'm grateful for all of them, but a forklift is not one of them. So, getting the MEP on solid ground in the time I had, wasn't feasible. I understand and agree though, that being on solid ground would help with dampening.
  • My end goal is to fabricate a trailer for this MEP, not ground mount it.
• I saw the comments about putting the top panel on. Again, I agree it will help with things. But I didn't have enough time today to do that test as well.
• The whole engine run only lasted ~5-10min. It's still not making AC power, so I need to debug that still. I saw no point/value in running longer at this point.
• As you see in the startup video, I touched the engine block and generator housing. Without a doubt, the engine has more vibration than the generator housing.
• The video shows well the forward/back vibration of the control panel. But as I was looking around the engine, the top of the radiator is also moving forward and backwards with vibration. Everything is securely mounted, it's all from vibration.
• The videos show the batteries dancing around a bit. This is the best visual indication I have showing the bottom skid has vibration going through it as well. I haven't yet gotten around to fabricating a tie down system for them.
  • As I've researched other MEP-802 YouTube videos, I've seen several with loose batteries and they aren't dancing around like mine. Again... an indicator of more vibration than expected.
• I utilized my Fluke Multi Meter and thermocouple to take some measurements around the exhaust ports.
  • Measured at the head
  • Measured at the exhaust manifold.
  • Cylinder towards the radiator was always 20-30 degrees F cooler than the cylinder towards the generator housing.
  • I took 3 measurements. 1 right after the startup video... still warming up. 1 after all the videos. and 1 after I shut it down. Ending temperature of the rear cylinder was ~160F
  • I neglected to monitor the temp gauge or radiator hoses to see if the thermostat opened up.

Questions:

• Is that 20-30F difference in temperature significant enough to indicate an engine issue? If so, any easy hints/links on where to go look up that process. I have all the manuals, I intend to look for myself, I just haven't yet. But like everyone, I welcome any free hints/tips.
• Any qualitative guidance on the rubber mounts? Again, the engine one I can poke my fingernail into. The Generator housing one, I can't. Should that be the case?
• Anything else stand out to people

 

[Daybreak]

Power the generator up.
You are running it to low a RPM
You want the 120/240 running at 60Hz >speed it up<
Yes, the 2 cylinder will be even worse at a slower idle.

Note: Don't do any fancy youtube processing. Just straight upload. Don't shoot video in portrait mode.

Here is one of my MEP-802A units being load banked. You can hear the lifting eyes clanging, since it is running on a pallet.

Same unit another day sitting on the ground.