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MEP-80X Blow by

jimbo913

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Hi Everyone, I purchased a new to me trailer mounted 802A and I have concerns about crankcase pressure.

A little background on the unit. The genset is 1999 with a remanufactured engine and the trailer has a date of 10/12 painted on it so I am thinking it went through a reset in 2012 and hasn’t seen much use since then based on condition of the block, etc. There are partial remnants of a small tag and wire tie under the emergency stop button but no longer legible. This could be a break-in tag or who knows.

The unit runs good at idle with no load, has 60 psi oil pressure when cold (40f), and doesn’t smoke. I have not replaced the oil just yet, which looks lightly used but it does seem thin in weight to me, which has me thinking it could be break-in oil? I didn’t want to put expensive oil in it until I felt the unit was in good condition and I guess staying away from synthetic is good if the issue is that it’s not broken in.
I noticed some air/steam blow-by with the dipstick and/or oil fill cap removed (no load). I purchased a digital manometer and I measured up to a scary 2.5“ H2O at no load idle. The gauge jumped around from -.15 to 1.5 and worse 2.5.
I did notice that the air filter seemed at least a little dirty so I will replace that first but is there anything that can help if that is not the issue?

If the engine does have break-in oil, is that amount of blow-by common until rings seat? I do have some John Deere break-in oil if the issue is that rings have not seated.

If the rings are sticking should I run some seafoam or other cleaner in the oil and fuel prior to an oil change and putting new break-in or 15w/40 in it? If yes, how long should I run the engine and with or without load?

Appreciate the feedback. I really hope I don’t have a unit that needs rebuilt because it’s more than I want to get into. Unsure how to approach this situation since I don’t know the history of the unit and last thing I want to do is make things worse.
 

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jimbo913

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I have had several hours to do some more research and calm down, and I am thinking that all signs point to this being a low hour reman unit that has been doing lots of sitting. Unless someone convinces me otherwise I plan to add some sea-foam in the engine and run it to operating temperature, drain and replace with JD break-in oil.
From there I will go through normal break-in process and check the crankcase pressure at 50 and 100hrs (assuming I am right and it makes it that far).
If anyone has crankcase pressure values at various hour’s during break-in, that would be helpful. If not, I will come back and add my findings but it’s going to take awhile for me to put 50-100hrs on it.
 

Guyfang

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So how many hours are on the clock? Or is that a state secret?

You might want to down load all the TM's and the LO, and take a look at them. The LO, Lubrication Order, tells you when to service the set. The LO tells you that at 250 hours to change the oil. So if the set has more then 250 hours it most certainly will not have break in oil. The Army, in any case never ever heard of break in oil. When the set get to you, you run it. Put a new engine in it, you run it.

You wrote: There are some threads on SS. Mainly not running at low loads, varying load from 50-85% as much as possible.

There are a few threads about this. Read several and you will understand. Gen sets like to run at rated temps. To do that, its best to run them as close to 75-90% if you can. The set will thank you. Its all about combustion, and build up of unburned fuel clogging up your set.

You wrote: The unit runs good at idle with no load,

Idle is not a good word to use. Idle means to run an engine at low RPM's. Thats bad for these sets. Start it, adjust the Hertz to 60, leave it there. Do not turn it down when you shut it off. Leave it where its at, and when you start it again, it should be good.

You wrote: Unless someone convinces me otherwise I plan to add some sea-foam in the engine and run it to operating temperature, drain and replace with JD break-in oil.

Why? You are just wasting break in oil. If you have not changed it yet, start the set up and get it warm. Stop the set, dump the oil and filter and replace them. Then start it up, put a load on it, say 2-3 KW. Let it run there a few hours. Kick the load up to 4-5 KW and repeat. Then load it to 100%, (5 KW) and let it run a while. Make it work. Then take a look at things.
 

jimbo913

Active member
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Location
Maryland
So how many hours are on the clock? Or is that a state secret?

You might want to down load all the TM's and the LO, and take a look at them. The LO, Lubrication Order, tells you when to service the set. The LO tells you that at 250 hours to change the oil. So if the set has more then 250 hours it most certainly will not have break in oil. The Army, in any case never ever heard of break in oil. When the set get to you, you run it. Put a new engine in it, you run it.

You wrote: There are some threads on SS. Mainly not running at low loads, varying load from 50-85% as much as possible.

There are a few threads about this. Read several and you will understand. Gen sets like to run at rated temps. To do that, its best to run them as close to 75-90% if you can. The set will thank you. Its all about combustion, and build up of unburned fuel clogging up your set.

You wrote: The unit runs good at idle with no load,

Idle is not a good word to use. Idle means to run an engine at low RPM's. Thats bad for these sets. Start it, adjust the Hertz to 60, leave it there. Do not turn it down when you shut it off. Leave it where its at, and when you start it again, it should be good.

You wrote: Unless someone convinces me otherwise I plan to add some sea-foam in the engine and run it to operating temperature, drain and replace with JD break-in oil.

Why? You are just wasting break in oil. If you have not changed it yet, start the set up and get it warm. Stop the set, dump the oil and filter and replace them. Then start it up, put a load on it, say 2-3 KW. Let it run there a few hours. Kick the load up to 4-5 KW and repeat. Then load it to 100%, (5 KW) and let it run a while. Make it work. Then take a look at things.
I agree, I shouldn’t have stated “idle”, should have just stated at “no load”. I was running it at 60hz.

I didn’t mention the hours on the gauge because my understanding is that is not a realistic indicator. Gauges get swapped, replaced, etc., but the gauge has 790hrs and I didn’t mention it, but there was a reset tag riveted to the back of the unit but someone had removed it and no idea why.

I didn’t do anything else to the unit since I posted this thread because I am awaiting a new air filter.
My reasoning for installing break-in oil is that I believe the motor hasn’t been ran much since remanufactured. I could be wrong on that, maybe others can give opinions based on the photos. Since it has some positive crankcase pressure and therefore may not be broken in, why not treat it as needing broken in and run it with break-in oil? What does running it with non break-in oil accomplish if it already has positive crankcase pressure? What am I missing?
 

2Pbfeet

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If a machine has not been used in a long (long) time, it is possible to have water in the oil that starts to steam off when the engine first warms up. Is it possible the "blow by" that you are seeing is just that the oil is baking off some water?

If you haven't run it at temperature under full load for awhile, I would try @Guyfang's excellent advice on loading the generator up, and then see.

All the best,

2Pbfeet
 

jimbo913

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Location
Maryland
If a machine has not been used in a long (long) time, it is possible to have water in the oil that starts to steam off when the engine first warms up. Is it possible the "blow by" that you are seeing is just that the oil is baking off some water?

If you haven't run it at temperature under full load for awhile, I would try @Guyfang's excellent advice on loading the generator up, and then see.

All the best,

2Pbfeet
I don’t think it’s water because I measured the crankcase pressure with a manometer with the engine just after startup so it was nowhere near operating temperature to create steam, and the pressure was still high.
To your point though, it needs an oil change regardless before I run it again, so my thought is that I have the break-in oil and don’t currently have another use for it. It costs $30 and regular dino oil is probably around half that or slightly more. I could care less about $15 or $30 if it means that the engine has the best chance at a long life by using the break-in oil. Besides cost I have not heard a reason not to use break-in oil. I know the military didn’t use it in the field but that doesn’t mean it’s not the best thing to do if the engine doesn’t have much use on it.
I am looking for input, so don’t take what I stated as argumentative. Basically I have 3 types of oil in the shop, 15w40 rotella diesel, 15w-40 syenthic diesel and John Deere 10w-30 break-in. It’s currently 20-40f where I live.
 
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DieselAddict

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Break-in oil will not cause any issues so don't be concerned about using it. A fluids change is always done on any machine that is new to me. I'll give it a test run on the existing fluids (assuming the pass the sniff test) but soon after that, everything gets changed and the rest testing begins.

Let us know how it goes!
 

jimbo913

Active member
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37
28
Location
Maryland
Break-in oil will not cause any issues so don't be concerned about using it. A fluids change is always done on any machine that is new to me. I'll give it a test run on the existing fluids (assuming the pass the sniff test) but soon after that, everything gets changed and the rest testing begins.

Let us know how it goes!
Thanks for everyone’s input. I will report back if anything pops up during testing, etc. and I plan to provide followup crankcase pressure readings at intervals to see if things are improving.
One other question though, does anyone know the official name for the spring retention clips on the outlut terminal studs and/or where to get them? This machine was missing them and I can’t find them in the manual or online.
 

kloppk

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Those wire clips are part of the stud assembly. They don't have an individual PN.
Only was to get them would be from someone parting out an 802,803 and willing sell just the clips.
One could probably fashion something out of stiff wire to serve the same purpose.
That or double nut the terminals.
 

2Pbfeet

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Mt. Hamilton, CA
Those wire clips are part of the stud assembly. They don't have an individual PN.
Only was to get them would be from someone parting out an 802,803 and willing sell just the clips.
One could probably fashion something out of stiff wire to serve the same purpose.
That or double nut the terminals.
I got some hard copper wire (18ga +/-) and bent up a replacement. It is probably easiest to do by making a bending template on a block of wood with a few small nails and cutting the tops off.

The funny thing was that after running the generator for a few hours the missing one vibrated loose from somewhere, despite prior compressed air cleaning and vacuuming...

All the best,

2Pbfeet
 
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jimbo913

Active member
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Location
Maryland
I had some time today, so I added an angled drain fitting, changed oil and filters and took a peek inside the engine.

The first photo shows the pipe I put on the allen wrench to break the drain plug free. I can still hear the snap from when it let loose.

Second photo is the angled fitting I installed. I still need to add the correct piece of hose but I was able to modify a milk jug and easily drain the engine from up top.
The rest of the photos take you on a journey inside the engine.
 

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