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Onan 7.5 MDJE 3CR/2268AB New Toy


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  #1  
Old 04-02-2017, 10:21:11 PM
PnishrPW PnishrPW is offline
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Default Onan 7.5 MDJE 3CR/2268AB New Toy

Picked this up off CL a few days ago under duress, ( nah, been looking for a D/JB or DKD reasonable for awhile) for $120. First diesel Onan I've owned, maintenanced a couple in the past but that's it.

Unit is 99.9% complete and not in bad shape. Main issue: very low compression in both holes. Barring over the motor by hand very slight resistance is felt on compression strokes. No strange noises were heard from the bottom end. Oil is used but clean and doesn't smell hot/burnt.

Raw water pump is fried, fresh is questionable but nice green antifreeze in heat exchanger. Glow plugs show resistance (.9 on manifold/1.8 on other 2). Solenoid on starter seems to be hung up, going to pull starter if I can get compression. Fuel solenoid moves freely under finger pressure, as does gov/inj pump. Barring over the motor, diesel drips from fuel return ditto when prime lever is depressed.

It has a un-potted vr 21 and other than a couple of cut wires in the AC output box (cover is MIA...) overall electrical seems intact and in good condition. It has hi temp and lop switches. Start / stop & pre-heat switches feel good. Control box was someones pantry but no damage noted. Haven't put power to it yet, see no need till I have compression.

Done so far: not damn much... Looked it over a bit, started hitting hardware with PB. Vacuumed it some, baseplate/control box etc. Going to pull valve cover and see if it has stuck valves (Thx BigBlockChev) first, go from there. Hoping for something stupid wrong.

5hrs before I got this I scored 4 GC-2 6v golf cart batteries in decent condition (test 70-80%) for price of cores, was wondering what I was going to do with them...

More pix next post.
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Old 04-02-2017, 10:26:21 PM
PnishrPW PnishrPW is offline
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Default Re: 7.5 MDJE 3CR/2268AB New toy

Some more pix:
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Old 04-02-2017, 10:32:22 PM
PnishrPW PnishrPW is offline
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Default Re: 7.5 MDJE 3CR/2268AB New toy

How I found it, we broke his "liftin' tree" loading it. ""It only weighs about 300#"" sellers words, not mine...
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  #4  
Old 04-03-2017, 12:37:00 AM
Ray Lynch Ray Lynch is offline
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Default Re: 7.5 MDJE 3CR/2268AB New toy

Look like it could be a nice set.
Good luck with it.
Ray
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Old 04-03-2017, 07:04:21 AM
Kevin K Kevin K is offline
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Default Re: 7.5 MDJE 3CR/2268AB New Toy

Good deal. You got it for a reasonable price considering it's condition. Far too many sellers think that cold hunk of metal sitting on the ground is worth a fortune.
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Old 04-03-2017, 08:14:07 AM
PopsGarage PopsGarage is offline
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Default Re: Onan 7.5 MDJE 3CR/2268AB New Toy

WOW, great unit looks 100% better than the 1966 MDJB that I brought home in 1999 yours is all there mine had parts removed. Good luck with your project.

Bob
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Old 04-04-2017, 01:07:16 AM
PnishrPW PnishrPW is offline
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Default Re: Onan 7.5 MDJE 3CR/2268AB New Toy

Thx, I figured for the price I couldn't get hurt to bad ( unless I drop it on my toes... ). I spent a few minutes on it today, mostly spraying PB. Raw water pump may not be as bad as I initially thought, got it off today. If I end up using this gen I won't be using it. I'm going to try to get the valve cover off soon and check valve action, maybe I get lucky. If it has stuck valves I'll try to free them up without pulling the head.

Been spending some time researching/reading manuals, I can't seem to find a build sheet. If anyone has one could I please get a copy? Thx, D
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Old 04-04-2017, 03:20:16 AM
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OnanParts OnanParts is offline
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Default Re: Onan 7.5 MDJE 3CR/2268AB New Toy

Here ya go.
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Old 04-05-2017, 01:13:49 AM
PnishrPW PnishrPW is offline
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Default Re: Onan 7.5 MDJE 3CR/2268AB New Toy

Thx Onanparts!

Got to spend a few minutes playing with it today: I turned it over 3-4 times by hand - compression has a little more resistance now. I got the valve cover off, valves not stuck but seem to have significant lash. Next I'm going to check/set lash, maybe check lift. Didn't even mess up the gasket, surprisingly clean inside.

Got the starter almost out, small wire on solenoid given me da blues... Been pre treating most hardware since I got it with PB blaster, usually doesn't let me down. Actually, most all the hardware has been surprisingly drama free. Pulling the starter because solenoid seems stuck, would rather do this diag/repair on the bench. If I can get the starter serviceable, I'll try to fire it up.

Just for giggles, I pulled the glow plugs and shot some PB in. They actually came out nice and easy.

For now it still sleeps with the fishes...
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Old 04-05-2017, 05:04:34 PM
TLB01 TLB01 is offline
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Default Re: Onan 7.5 MDJE 3CR/2268AB New Toy

Looks like it might be relatively low hour and had plenty of time to sit around. Might want to crack open the control box and check for mouse houses. And seeds in the gen end.

Haha, you already did!
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