Mep-803a vibration

[chilbun28]

Hi all! I got the 803a delivered and all my new hoses and filters in and installed. I ran the switch in the normal run prime position for a couple minutes and then cranked the motor; fired right up. This one has a noticeable vibration that my other 2 803's don't have. This one vibrates pretty noticeably and when I adjust the hz adjuster and throttle it up it vibrates way more than I would expect to be considered common. This 803 has "I P" painted on the back cowling. One of our members mentioned it could mean injection pump. Any ideas on vibration issues with an 803? Thanks

 

[Scoobyshep]

Could be a cylinder not firing

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[DieselAddict]

Yep. Not firing on all 4 is the first thing to check. Break out the IR gun and measure the temps on the exhaust manifold. Should be obvious.

Don't run it any more than necessary for troubleshooting. In case there is something mechanical wrong. Minimize any possible damage that running it is causing.

 

[chilbun28]

What conditions would keep a cylinder from firing?

 

[DieselAddict]

Fuel, air, fire.. One of the three is missing.

Fire and air are related since its a compression ignition engine. Do you have compression? Is air getting into the cylinder?

For fuel its more straight forward. Is the fuel injection pump an injector working?

You'll need to do some troubleshooting to first find out which cylinder isn't contributing and then figure out why.

First test. Crank with dead crank swich. Does it turn over evenly or is there one spot where it sounds "different"? The cadence of the engine should be even. It shouldn't sound like it speeds up or slows down.

 

[Scoobyshep]

No fuel no air bad compression. If they labeled it IP id wager fuel

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[Ray70]

I doubt the IP or 1P painted on the box has anything to do with the machine's mechanical condition, it's probably some other inventory marking etc, but fuel delivery and running on 2 or 3 cylinders is still a probably cause of the vibration.
it would also cause you to not reach rated output, if you have done any load testing yet.
Others have reported serious mechanical issues ( loose flywheel bolts etc. ) as causing their vibrations, so if it's firing on all 4 you'll want to start looking deeper into mechanical assembly problems.

 

[chilbun28]

Here are readings after I let it run for several minutes.

 

[chilbun28]

Pics with readings from a little lower area.

 

[Ray70]

With the machine running I would crack open 1 injector line at a time and listen for a drop in engine speed and an increase in vibration / stumble.
If no change is heard, that cylinder may be dead. The cyl closest to the fan appears much cooler but that may only be due to the fan blowing more air on the first cyl. than the others.

 

[WWRD99]

Hi all! I got the 803a delivered and all my new hoses and filters in and installed. I ran the switch in the normal run prime position for a couple minutes and then cranked the motor; fired right up. This one has a noticeable vibration that my other 2 803's don't have. This one vibrates pretty noticeably and when I adjust the hz adjuster and throttle it up it vibrates way more than I would expect to be considered common. This 803 has "I P" painted on the back cowling. One of our members mentioned it could mean injection pump. Any ideas on vibration issues with an 803? Thanks

So I gotta ask...how much vibration is actually happening? Is the engine bouncing around or is it just loud and clanky...Is everything tight like belts and air cleaner lids? How old is the fuel? Have you run a cleaner through it yet? What oil are you using? How many hours are on it? Does it make power? 10 degrees difference on one cylinder isn't that much on one that is just started.

 

[Guyfang]

If loosening the individual injector line is not showing you any joy, take a look inside the set. Make sure the two front rubber vibration dampers are:
1. There. Dont laugh, I have seen it.
2. Tight. Read the -24 TM to get smart about these things.
3. All the hardware is there. Look at the 24P to find out what should be there.

Then, do the same with the two rear dampers. If all this is in order, then you need to dig deeper. Maybe the bearing in the main AC. Or Man AC bolts.

The front jug is indeed a little low temp. Loosen the IP up for the front Fuel Injector, and adjust it, a hair at a time, to see if you can raise the temp on that jug.

 

[chilbun28]

I cracked open each fitting atop each injector pump one at a tome and the motor began to sputter a little and basically the same amount for each of the 4.

The motor feels fine, just a little vibration. But it's on a military trailer, and standing on the trailer I can feel it vibrate pretty good, more than my other 2 generators.

The shock dampness are in place, tight, and appear to look very good. The generator is also mounted tight to the trailer.

Completely drained the diesel that came with the unit and filled up with fresh diesel. Changed both fuel filters and air filter.

Changed oil and filter. Chevron delo 5w-15

I had to change the 4 fuel hoses that go from the little manifold line to each injector pump. The 1/4" fuel hoses that are maybe 4 or 5" long. The original ones were cracked bad and one was leaking. I changed all that before I put new fuel in it and ran it for the first time.

 

[Digger556]

Also rotate the engine by hand and look at the flywheel through the vent holes in the generator head.

People have a tendency to jam a screw driver in there when loosening or tightening the crank pulley and could have damaged the flywheel, throwing off its balance.

 

[Scoobyshep]

Also rotate the engine by hand and look at the flywheel through the vent holes in the generator head.

People have a tendency to jam a screw driver in there when loosening or tightening the crank pulley and could have damaged the flywheel, throwing off its balance.

Those barbarians!

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[Ray70]

I'm curious it you actually have a problem here or not??
Sounds like it's running fine.
Can you send a picture or video? does the trailer happen to have the solid plate ( maybe 18" wide or so? between the longitudinal rails up front, in front of the wheels? I have had 2 trailers where that plate was visually vibrating severely due to the harmonics of the generator.
The gen was fine, it was the trailer making all the noise and vibration because 1 had a loose plate, the other was bent ( bowed down slightly ) causing it to vibrate against the rails despite being bolted tight.
How much is the chain on the oil fill cap dancing around while running? is it shaking a bit or bouncing all over the place?

 

[justinn]

Are your other 2 gens also on trailers? The trailer units seem to have more harmonics that get transferred through them as opposed to the gen's sitting on the ground. If you think an 803A has vibration on a trailer, the 802A's are like standing in a rock tumbler

#1 IP may be slightly sticky, but it still has decent temp in it, so I would run a couple cans of seafoam through it and go from there.

The others have pretty much covered everything that is ~could be if indeed something is wrong.

Justin

 

[Ray70]

If you do adjust IP#1, take a piece of cardboard and hold it vertically at the left end of the exh. manifold to shield the end of the head from the air coming off the fan. Run it under a moderate load for a little while, then take the temps of all 4 cyls. again.
You'll never get an accurate reading across all 4 if you don't block the airflow.

 

[smokem joe]

I had an 803 that had a vibration in it. It was just as bad as an 802 while running. Guyfang suggested pulling the stator, unbolting the rotor from the flywheel, and turning the rotor halfway around before reinstalling the bolts. This did not completely fix the problem, but it did bring it down to just slightly above normal amount of vibration.

 

[Digger556]

Chilbun, do you happen to own an oscilliscope?