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Mep-802A crank no start, high crankcase pressure

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KnuckleDuster

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New jersey
I recently purchased a 2009 mep802a from govplanet with a trailer for $900. Sold the trailer as I don't need it for $600 and got started on the generator. I found the alternator was missing, fuel bowl, battery cable, and the 3 amp fuse for the voltage regulator were all missing as well. Sourced all new parts got it all put back together bled the fuel system and got it cranking. No start. Not even an attempt. Shot a sniff of starting fluid into the intake and it didn't even sputter. I know it's not a fuel concern. Pulled the dipstick while cranking and the pressure coming out of the crankcase was pushing oil all the way up the dip stick tube. Starting to think maybe a stuck or broken ring. Anyone come across this? Unit is high hours, sitting right at 3400. Found the shipping tag and it was actually in Kuwait working. Thanks for any advice! Not sure if im missing something else to check
 

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Ray70

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Could be rings and I've seen my fair share of stuck valves, often times not frozen but just not seating due to excess carbon buildup around the valve and it's seat. Could be several other issues too.
With that much pressure in the crankcase just spinning the motor over, I'd lean towards a piston / ring / cylinder wall issue.
I've seen wrist pins come out and gouge the cylinder wall, seen holes in pistons, smashed ring lands, broken rings, bent / tweaked connecting rods.
does it sound like it has compression or is it pretty much spinning freely?
In addition to the crankcase pressure remove the air intake hose from the manifold and crank it over, see if you feel pressure blowing back out.
The good news is these are such simple engines you can have the head off in about 15 minutes if you need to dig in deeper.
 
K

KnuckleDuster

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New jersey
Ray70 said:
Could be rings and I've seen my fair share of stuck valves, often times not frozen but just not seating due to excess carbon buildup around the valve and it's seat. Could be several other issues too.
With that much pressure in the crankcase just spinning the motor over, I'd lean towards a piston / ring / cylinder wall issue.
I've seen wrist pins come out and gouge the cylinder wall, seen holes in pistons, smashed ring lands, broken rings, bent / tweaked connecting rods.
does it sound like it has compression or is it pretty much spinning freely?
In addition to the crankcase pressure remove the air intake hose from the manifold and crank it over, see if you feel pressure blowing back out.
The good news is these are such simple engines you can have the head off in about 15 minutes if you need to dig in deeper.
Click to expand...
It feels like it has decent compression and I hear it exhausting out the muffler. I pulled the valve covers off yesterday, it's clean up top but I'll drop the head today and see
 
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Ray70

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Are you getting any smoke at all out of the exhaust?
If the issue is low compression you would typically get a bunch of light gray smoke.
If you aren't getting any smoke at all I would still suspect no fuel despite no results from the starting fluid.
I'd do a little more digging before pulling off the head, to verify you are getting fuel to the injectors.
Verify fuel is reaching the metering pumps through the rubber lines going into them.
Verify the fuel solenoid is retracting when you are cranking.
Crack the lines at the injectors and verify you are getting very small spurts of fuel at the injectors.
I would even pull the injectors and check for compression before I pulled the head, but you need to rig up a compression tester and gage, which you probably don't have handy.
If you can get one of the old school compression testers with the rubber tip you would normally just press up against a sparkplug hole, your engine should max out the 300 Psi gage. You want to be up around 325+ , Preferably more like 375+ in a cold dry cylinder.
If you are below 325 it isn't going to run.
 
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KnuckleDuster

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Location
New jersey
Ray70 said:
Are you getting any smoke at all out of the exhaust?
If the issue is low compression you would typically get a bunch of light gray smoke.
If you aren't getting any smoke at all I would still suspect no fuel despite no results from the starting fluid.
I'd do a little more digging before pulling off the head, to verify you are getting fuel to the injectors.
Verify fuel is reaching the metering pumps through the rubber lines going into them.
Verify the fuel solenoid is retracting when you are cranking.
Crack the lines at the injectors and verify you are getting very small spurts of fuel at the injectors.
I would even pull the injectors and check for compression before I pulled the head, but you need to rig up a compression tester and gage, which you probably don't have handy.
If you can get one of the old school compression testers with the rubber tip you would normally just press up against a sparkplug hole, your engine should max out the 300 Psi gage. You want to be up around 325+ , Preferably more like 375+ in a cold dry cylinder.
If you are below 325 it isn't going to run.
Click to expand...
I have verified all of that short of doing a compression test. I get fuel spitting out right at the injectors when I cracked the lines. But surprisingly, not much smoke out of the exhaust. I don't think the injectors are of any concern though as they appear to be firing. Other than taking them out and having them pop tested I've ruled out alot of other possibilities. I will try to do a compression test tonight and post my results
 
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KnuckleDuster

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New jersey
Ray70 said:
Ok, sounds good.
Since you have to pull the injectors to do a compression test, you can also turn the line off to the side and hook the injector back up with it out of the cylinder to test it. You should have 4 very fine sprays coming out of the sides of the tip at 90* spacing.
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Okay here's what I found. Injector tips covered in sludge, bird seeds probably from mice in both intake ports filled to the brim. Decided to pull head to clean and found the bowl of the rear piston packed to the top with seeds and dirt. Cleaned all that, wiped out the cylinders, took the head apart and noticed the same sludge in all the intake and exhaust ports. Still doesn't explain high crankcase pressure. So I'm concerned about that. Should I yank the pistons to see if the rings are gunked up?
 

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KnuckleDuster

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Alright I got it torn down. Rings were stuck in the ring lands in the piston. Running it for a while may have loosened them up but I'm glad I got it all apart to do a real cleaning and all new gaskets on it. Got the head soaking now in the parts washer I'll clean it all up tomorrow, dingle ball hone it and wait for my rebuild kit. I won't be messing with the crankshaft but I'll change the rod bearings, rings, pistons, and valve stem seals while I'm here
 
loosegravel

loosegravel

Just a retired mechanic who's having fun!
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KnuckleDuster said:
Alright I got it torn down. Rings were stuck in the ring lands in the piston. Running it for a while may have loosened them up but I'm glad I got it all apart to do a real cleaning and all new gaskets on it. Got the head soaking now in the parts washer I'll clean it all up tomorrow, dingle ball hone it and wait for my rebuild kit. I won't be messing with the crankshaft but I'll change the rod bearings, rings, pistons, and valve stem seals while I'm here
Click to expand...
You’re going to find those pistons very difficult to locate. And when you find them, they’re like gold in price. If at all possible, I would clean and reuse them. Can you see any marks on the top of them indicating the oversized? Those marks are in mm, not inches.
 
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KnuckleDuster

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loosegravel said:
You’re going to find those pistons very difficult to locate. And when you find them, they’re like gold in price. If at all possible, I would clean and reuse them. Can you see any marks on the top of them indicating the oversized? Those marks are in mm, not inches.
Click to expand...
I found a kit on eBay that lists the pistons. I'm sure they are aftermarket. Mine are not damaged and can be saved so maybe I'll just reuse them and throw the new ones on the shelf if I ever need them. I see marks on them I just don't know what the original size is to tell you if they are oversize
 
loosegravel

loosegravel

Just a retired mechanic who's having fun!
504
892
93
Location
Enumclaw, Washington
KnuckleDuster said:
I found a kit on eBay that lists the pistons. I'm sure they are aftermarket. Mine are not damaged and can be saved so maybe I'll just reuse them and throw the new ones on the shelf if I ever need them. I see marks on them I just don't know what the original size is to tell you if they are oversize
Click to expand...
I started a thread last year around March or so. It was titled “DN4M pistons.” It was a 10 kw unit which has basically the same engine with two more cylinders. You may find some good information in that thread regarding how to decipher the numbers on top of the pistons. If my memory serves me correctly, mine ended in .250, which is .250mm oversized.
 
K

KnuckleDuster

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Location
New jersey
loosegravel said:
I started a thread last year around March or so. It was titled “DN4M pistons.” It was a 10 kw unit which has basically the same engine with two more cylinders. You may find some good information in that thread regarding how to decipher the numbers on top of the pistons. If my memory serves me correctly, mine ended in .250, which is .250mm oversized.
Click to expand...
I just read that thread. Lots of good info. I go out in the shop and take a photo of the top of the piston to see what it says.
 
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Ray70

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KnuckleDuster, if you haven't already purchased the pistons, you can also just get new rings from Mayi Diesel in standard bore .25mm .5mm .75 and 1.0mm oversizes.
Just clean your ring lands good, hone and re-ring it.
Let me know if you have any difficulty finding rod bearings, I have a couple extra standard rod bearing sets in my parts stash.
 
K

KnuckleDuster

Member
27
42
13
Location
New jersey
Ray70 said:
KnuckleDuster, if you haven't already purchased the pistons, you can also just get new rings from Mayi Diesel in standard bore .25mm .5mm .75 and 1.0mm oversizes.
Just clean your ring lands good, hone and re-ring it.
Let me know if you have any difficulty finding rod bearings, I have a couple extra standard rod bearing sets in my parts stash.
Click to expand...
I could use the rod bearings. I'll change them because I'm here. Thanks!
 
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