How to separate 7.5JB motor from generator?

[51f1]

model # 7.5JB-18R120997AC
Serial # is D810565887
This unit is in great shape, except for engine crankshaft seals. Leak stopping additive did not help, but our driveway is now really rust-free. I welcome advice and tips on separating engine from generator. I'm ok with seal installation, as I also suffer from incurable old car disease. 'Never did an Onan generator though. Thanks from Gene in Sacramento.

[Billy J Shafer]

Mark all your wires that you remove. So you will know where they go when you put it back. Remove the end bell with the bearing in it. Should have F1-F2 wires on it. With the end bell removed you can then remove the stator. Try not to let it drag on the rotor. Remove the center bolt from the rotor.

Then lay something under the rotor to catch it when it falls. Place a block of wood on the rotor shaft and hit it with a large hammer. Rotate the rotor and do the same thing over again. It will pop off,but it may take a few hits. Be sure to hit the shaft not the windings.

My best car was a 1962 Studebaker Hawk GT.

[51f1]

Thank you, Billy! Especially for your advice on wires. That Studebaker was a great looking car, and I'm told a pretty fast one. Gene in Sacramento

[Ironsides]

Gene,silly question but I have been caught before.Did you check the breather was clear and working correctly before you made the decision to strip and replace the seal?Good luck,keep cranking,Norm

[51f1]

Regarding the breather, good point. I did check that, thanks to this website. Clean and clear. Then tried the "leak stopping miracle" additive, but no divine intervention as yet. It leaks from the rear main, engine running. Still leaks w/engine off, if on a slight rearward incline.

[bobbyz72]

Its not hard at all to take off generator end and replace seal. Once you start on it, you will see its nonthing too it.

[Max Thompson]

Allow some time to get the rotor off the shaft. I have pulled a couple on JCs recently, one came with a little time & few bad words, the other took several hours, heat, very carful prying & a lot of bad words. Hopefully you will get lucky.
I would replace the bearing on bell end of shaft while I had it apart, about $30 at the local auto parts store.
Max T.

[Billy J Shafer]

Max is correct. It can be a bear at times and you get to talk funny. The way I told you is the simple and everything going right way. Just remember to remove the center bolt holding the rotor on(). Good idea about changing the bearing.

The Hawk was fast. Ran so smooth down the highway that you did not think about your speed. Got out of many 100 mph plus tickets. Buy letting the officer drive it around.

[Dave Edmonds]

I used the "Billy Method" on the one I had to take apart, and it came off easy, ONCE I remembered to remove the bolt holding the stator on (step 1 - remove all attaching hardware)!
You won't have to do this, but if yours has an aluminum coupler/fan on the engine end of the rotor, getting it off the rotor is a different matter entirely. The part that fits the engine is tapered and keyed, the part that fits the rotor is straight, and the aluminum will gall to the steel. A 20-ton press was required to separate the two parts!
Good luck.
Dave Edmonds

[51f1]

Many thanks to Dave, Billy, Bobby, Max, Norm et al regarding my leaking generator seals. It will be my late August project. Gene in Sacramento

[Dave Edmonds]

OOPS! I said "stator"; I meant "rotor" (you know, the thing that goes around). My bad!
Dave Edmonds

[J. McNugget]

On a related note, now that the gen end is off, how does one calibrate an adjustment to the oil pump pressure relief that is accessed at the back of the engine? My DJC could stand 10 more hot PSI, but I wouldn't know how much to turn the screw before reassembling to test my adjustment.

THx
John

[BrainAllinger]

The Oil bypass valve is not adjustable.

[Richard L]

I leave the center bolt in, run the nut out to the end, support the rotor with a block underneath it, place a short block on the rotor and hit it with a heavy hammer, while rotating the rotor, if that doesnt do it then using a heavy hammer and hit the nut on the center bolt dead on, make sure the nut and the threads are even,the center bolt being in place will keep the rotor from sliding all the way away from the engine and dropping out

[Wayne 440]

It may not be intended or designed to be adjustable, but there are ways to do so.

Originally Posted by BrainAllinger

The Oil bypass valve is not adjustable.