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New MEP-803 motor issues

springbok

New member
320
16
0
Location
Wilmington Delaware
I figured I would run it past here to see if I missed anything.
I picked up an almost new (less that 200 hours tops) Onan motor that was blowing a great deal of oil out of the #2 cylinder.
I took the head off, gasket is fine.
After digging more I found that someone ran gas in it, not sure the ratio and/or for how long.
The Cylinder walls seemed pretty well glazed so I honed them to scuff them up.
All pistons went through my ultrasonic cleaner and no cracks in them.
Removed the valves and cleaned them, one, on a different cylinder had very minor gauzing, cleaned it up and still less than .002 movement in the guide.
Valve seals look fine. Bearings all look good.
Before putting it all back together, anyone else have ideas.
I am thinking it was the glazed cylinders but who knows...
 

novaman

New member
70
0
0
Location
michigan/Livonia
Sounds like the problem was the home. R u sure it wasn't just wet stacked from running with out enouph load on it? I've heard the onan engines have issues with that if not kept to at least 30% load during operation. How long did you let it run for with a load before you pulled the head off? My 802 smoked for about 10 mins w/5000watt load before it sealed itself with the very first time I got it running. But then tightened up and now can handle 7500+ watt loads easily. Also only 120 hrs on my unit
 
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springbok

New member
320
16
0
Location
Wilmington Delaware
The issue is someone ran gas through it. I will have it back together this weekend but wanted to make sure I did not overlook anything obvious someone may know about before I do.
If it had a starter with it I would have just run it to see if it cleared up but hey it was fun for my son and I to open it up...
 

novaman

New member
70
0
0
Location
michigan/Livonia
So the person you bought it from disclosed this to you? or was the tank still full of gas? Or was there something else that lead you to believe gas was ran in the unit
 

springbok

New member
320
16
0
Location
Wilmington Delaware
It came from GL, just the motor. Got it home and could see there was a good deal of oil that had come through the #2 cylinder, exhaust was pretty sooty as were the valves...
During the process of opening it up to see what the cause was, as if it was a hole in the piston I would have sold it for parts, I took off the fuel filter and at that point you could smell the gas.
Rings look fine but the cylinder walls were glazed pretty nicely...
I removed all the valves, cleaned them and made sure there was no slop in the guides.
There was no blowback into the valve covers. No cracks in any of the pistons.
Just looking for any other things I should check as new head gaskets are not cheap so once it is together it is not coming apart again.
 
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