MEP802 - Got a shaker.

[DieselAddict]

I picked up a couple of 802s from auction last week. These were Tier2 resets with less than 20hrs on the clocks. Very clean. Both had remaned engines in them. One had a poorly rebuilt DC alternator (fixed) and the other one seemed to have no problems, except...

This thing shakes a LOT. And by a lot I do mean a LOT. A LOT more more than the one I repaired the alternator on. It shakes enough that it broke one of the wires going to the low oil pressure switch. The manafold where the pressure transmitter and low pressure switch attach next to the "Dead Crank" switch wiggles a good 1/3" when its running. I did some strain relief to the wires when I replaced the connector so I doubt the wire will break again but I am concerned.

I've covered the simple stuff.. I made sure it was well supported on the skids. It is firmly strapped down and makes good contact with the back of the F350 that its in. I've checked all the bolts and the mounts holding it down (engine end and alternator end). Everything looks new and tight. The engine runs strong. It easily took 6500w of resistive load and held that for an hour with zero problems. The puffs from the exhaust are strong and clear. I only get a bit of black smoke when I drop the hammer on it with the load.

None of the fan blades are missing or bent. I checked most of the enclosure bolts to make sure they were snug. So far I've not found anything at all loose. Tomorrow I'm going to take the belt off and start it to double verify its not a fan related issue.

The vibration appears to be 1x RPM which would indicated its a balance or alignment issue.

Has anyone had an 802 that shimmies and shakes? If so did you ever figure it out?

Does anyone know how the engine is balanced? Internally versus externally?

Can the coupling between the flywheel and AC Alternator be misaligned?

Lots of questions I know but if anyone has some ideas I would be happy to hear them.

 

[Dewie38]

I can tell you that a lot of 802's had oil press switch wires that broke at the connectors.
When we have a set that vibrates a lot sometime we rotate the generator.
Disconnect the rotor and rotate 90 degrees and reconnect to the engine.
These 2 cylinder engine do vibrate a bit, some more than others.
Also check to make sure they didn't install the wrong rubber isolation mounts, 5 and 10 kW's look the same but I believe the 5 kW's are not as stiff as the 10 kW's for this vibration issue.
I've seen these units vibrate so much that the movement on the panel meters come apart.
Just some thoughts.

 

[DieselAddict]

Luckily this one doesn't seem to vibrate enough to shake the meters apart.

Is there a simple way to check that the right mounts were installed?

Rotating the generator rotor was one of the things I was considering to try. Thanks for mentioning it.

 

[Dewie38]

Sorry
Only way I know of is to check the part number on the mounts.
Like I said they look the same and are interchangeable but the 10 kW mount on the 5 kW will cause issues.

 

[DieselAddict]

I was afraid you were going to say that.

 

[Dewie38]

I remember a long time ago one of our supply chain workers took all the mounts and put them all in one bin on a shelf, cause they all looked the same, boy did that cause big problems during assembly.
Some one had the nice job of separating all of them, and I believe the only way to tell the difference was to look at each and separate by part number stamped on them.
I think I was incorrect and the 5 kW may be a stiffer mount cause you want less movement, a softer mount would allow the engine to move more (and you don't want that).
Anyway, I think if you really want to go that far and if you think the vibration is that bad, then rotating the gen would be the thing to do.

 

[DieselAddict]

I talked to one of my friends I grew up with. He recently retired from the Army. He indicated that all the 802s he dealt with shook a lot. Maybe the one that doesn't shake much is the outlier.

 

[Daybreak]

Howdy,
I guess the side nick name for a 2 cylinder motor would be "Shaker"
I just fired up my new acquisition MEP-802A and its not the outside that shakes, but open the door,and watch the motor shake.
The MEP-803A being 4 cylinders is so much smoother.

 

[cuad4u]

My reset 802A with 14 hours does not shake. Maybe I got a good one. Granted is is not quite as smooth as the 803A but when putting my hand on the case I really don't feel much vibration. It is sitting on but not bolted down to a concrete pad.

 

[dependable]

As noted, the two cylinder diesels tend to shake due to piston configuration. I thought my 802 was shaking too much (compared to a 002)when I had it running on a truck bed. When I put it on a piece of old rubber truck bed liner (similar material as mud flaps) on a concrete slab, most of the shaking stopped.

 

[uniquify]

Did you ever get your shaker to settle down?

I recently picked up an 802 built in 2006 with original 18.5 hours, and it shakes so much I suspect that's the reason it was put up for auction. I got a good price and it holds 7000w resistive just fine, but the way it shakes makes me doubt its longevity. I have a reset 803 that runs so much smoother and a little quieter, I'm half tempted to sell the 802 to buy another 803. However, if I can get the 802 to calm down, it could meet my needs on half the fuel...

I'm curious how much difference does rotating the generator rotor could make? How easy/hard is that?

 

[DieselAddict]

Its smoothed out a good bit after I ran it for a while. I learned after looking at a bunch of them that they do shake more than the 4cyl machines.

It went to its new home in South Carolina a couple of months ago and the new owner is very happy with it.

 

[Daybreak]

Howdy,
I found mine also settled down after I set it on the dirt or cement floor. It did not help being on a wood pallet. The nature of a 2 cylinder is just not as smooth as a 4 cylinder.

 

[uniquify]

Thanks guys, that's really encouraging. At the moment the 802 is sitting on a wooden dolly and casters that I originally threw together to move the 803 around. Perhaps there's enough flex in the 2x6's that it's exaggerating the shaking. I think I'll set it directly on the concrete during the next round of load testing and see if that makes a difference. Long term plan is to bolt it down on a pad beside the garage, possibly with some sort of rubber cushion.

 

[lindsey97]

Adjust the fuel metering pumps so that the exhaust ports match in temperature, and that the load is shared between the 2 cylinders?

Or balance and blueprint the rotating assembly.

 

[Guyfang]

I agree with Dewie38, You need to check the part numbers on the bottom of the shock isolator mounts. We also found that if the big washers were not installed on the mounts, (and yes, a bunch came from RESET that way) it quickly wore them out.

If that doesn't pan out, another fault we found that caused shaking was the injector pumps were not set right! Lindsey hit that one on the head! This problem had me stumped for a while. A CECOM friend told me to use a temperature measuring device, to adjust the injectors pumps. And, sure as can be, that helped bring it down to an acceptable level.

I also found that several times, the Main Gen was not properly mounted to the engine. You could loosen all the bolts, then turn it over by hand a few times before retightening it. And twice I found a vane on the Main gen was damaged.

Only once, did I see any vibration problem that originated in the engine side of the gen set. The fan was installed backwards. It was ALWAYS on the Main Gen side, or mounts. The fan is easy to check. just look at which way the vanes are bent.

 

[lindsey97]

Couple of questions: Can you adjust the metering pumps to match one another without a load on the generator? Or should the procedure be done with, say 50% load or more on the generator?

I checked mine with the engine warmed up to 170 deg F water temp, and both exhaust ports were within 10-15 degrees of each other, at 223-237 deg F.

 

[Guyfang]

Both ways. Either or. We did it mostly with a small load. Plugged in a heater or coffee pot. Let it get warm, the turn on the load.

 

[fastbrass]

Hi all, I've recently acquired an 802a built in 06 with the hour meter showing 220 hours. Overall clean, seems to be in good shape, and runs pretty well. However, it does seem a bit shaky.

I'd like to try and adjust the fuel metering from cylinder to cylinder as mentioned above, but I cant seem to find any info on what to adjust or how to go about it. Can someone point me in the right direction? Thanks!

Mike

 

[jamawieb]

So, take the hard line loose (barely) on the injector pumps, then take the hold down nut loose (barely). Then you can turn the injector pumps while the set is running. You need a infrared thermometer so you can take readings at the exhaust ports. Turn the pumps clockwise to increase fuel, which will increase temperature or counter clockwise which will decrease the temp. When you get both exhaust ports approximately the same temperature, your set.