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Rich Biebel · 08-25-2014, 07:54 PM

Sean this is a bad one and I am really sorry to read about all you grief trying to fix it...

Did you ever do a valve lash check yet on this one. I don't recall as it has been a while.

They use solid lifters. Lash is very small at about .003-.004 cold.

There is only one way to do this and it is difficult but I know you can do it.

Under the generator end is a plastic plug. Pop it out....I tape a 15 or16MM socket( can't recall which right now) to an appropriate length extension. There is a bolt in the end of the generators rotor.....straight up from the hole where you popped the plug out of. This is the only way to rotate the engine and to do the valve lash check. Spark plugs out....rotate it in the proper direction and do it like any 4 stroke engine. They are a real pain to do and they get tighter as you lock the locknut....and the studs like to loosen up sometimes. If you watch the valves it's easy to see the proper sequence so you know your turning it in the right direction.
If the exhaust valve lash is tight....once the engine gets hot the valves do not seat and compression is lost and exhaust backs up into the intake....Might be your problem. It is counter clockwise if you were looking up at the rotor bolt your turning....

If you see heavy deposits of oil sludge around your exhaust springs.....you could easily have loose guides. They do it on a regular basis.....I wiggle the springs/valves trying to see if there is movement. The seal might move....if it does.....You need to replace the head or both of them. Now when I find one side bad.....always the left side.....I pull them both and take them apart. If the exhaust guides are loose, I install new heads.....both and have done about 3 in the last 3-4 months....The y are press in guides and loosen up.....and the valves and seats get beat up. High heat is when they really start running bad or may shut off...

Fuel supply is good.....Ignition is good....12 volt supply stays up to the pump and solenoid.....it should not shut down....

Ignition coils get grounded to shut it down. They are magneto style....don't need a battery to make spark...only need to be grounded to shut them down....

Starts to make me feel it might be the head issue....

08-25-2014, 07:54 PM	#26
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,315 Likes: 25 Liked 544 Times in 213 Posts	Re: Onan 7000 Generator problems Sean this is a bad one and I am really sorry to read about all you grief trying to fix it... Did you ever do a valve lash check yet on this one. I don't recall as it has been a while. They use solid lifters. Lash is very small at about .003-.004 cold. There is only one way to do this and it is difficult but I know you can do it. Under the generator end is a plastic plug. Pop it out....I tape a 15 or16MM socket( can't recall which right now) to an appropriate length extension. There is a bolt in the end of the generators rotor.....straight up from the hole where you popped the plug out of. This is the only way to rotate the engine and to do the valve lash check. Spark plugs out....rotate it in the proper direction and do it like any 4 stroke engine. They are a real pain to do and they get tighter as you lock the locknut....and the studs like to loosen up sometimes. If you watch the valves it's easy to see the proper sequence so you know your turning it in the right direction. If the exhaust valve lash is tight....once the engine gets hot the valves do not seat and compression is lost and exhaust backs up into the intake....Might be your problem. It is counter clockwise if you were looking up at the rotor bolt your turning.... If you see heavy deposits of oil sludge around your exhaust springs.....you could easily have loose guides. They do it on a regular basis.....I wiggle the springs/valves trying to see if there is movement. The seal might move....if it does.....You need to replace the head or both of them. Now when I find one side bad.....always the left side.....I pull them both and take them apart. If the exhaust guides are loose, I install new heads.....both and have done about 3 in the last 3-4 months....The y are press in guides and loosen up.....and the valves and seats get beat up. High heat is when they really start running bad or may shut off... Fuel supply is good.....Ignition is good....12 volt supply stays up to the pump and solenoid.....it should not shut down.... Ignition coils get grounded to shut it down. They are magneto style....don't need a battery to make spark...only need to be grounded to shut them down.... Starts to make me feel it might be the head issue.... __________________ Rich Biebel S/C 1479 Stock 147R Last edited by Rich Biebel; 08-25-2014 at 08:00 PM.