648 project. Long story pictures at bottom

[JSinMO]

Here’s the story on our 648. I stumbled on the tractor by accident, I wasn’t looking for another tractor! After taking a look at it I couldn’t help myself, I had to bring it home. It did come with some documents and manuals so that’s a definite plus. I know it was sold new in St Louis and I’m the 3rd owner. The previous owner parked it 10 years ago outside and really didn’t touch it again until recently when he tried to get it running with no luck. The hour meter shows 790 hours and it looks to be a pretty complete unit.
I figured we should probably check out the engine first to see if it has any chance of running again.
This has the B48M Onan 18 HP engine in it. Since it hasn’t run in quite awhile we took the intake and carburetor off for cleaning.
I’m glad we did because we found there was a missing intake gasket, I’m guessing that happened when the previous owner tried to get it started. The inside of the carburetor was as expected, plugged up!
We cleaned it up and resealed the seam in the intake manifold. The engine oil actually looked pretty good. No water or gas in it. We decided to soak the cylinders with ATF to loosen the rings and give some lubrication.
Son had absolute confidence it would run I had my doubts after sitting outside abandoned for so long. We let it soak for a week until we had time to work on it again. After getting the ATF out of the cylinders I put a battery in and decided to see if we had compression. With my thumb or the spark plug hole son hit the key. Both cylinders have compression, good sign. Next I checked sir spark, nothing. A quick cleaning of the points and now we have spark, great sign! We knew our carburetor and intake were good so I made new intake gaskets and remounted the assembly.
The gas tank looked a little rough so we supplied gas with a temp tank. changed the oil and filter and decided to give it a try….
The engine came to life so quickly it surprised us both! It ran like it had been shut off the day before, you would have never known it had sat for a decade. Now that it was running we just had to try it out.
Hoe works, loader works, we have power steering, but, we only have low gear. With the transaxle in high gear the tractor will not move.

We had made good progress and we’re exited to continue. I decided the next steps would be to remove and inspect the gas tank, which ended up needing a patch on the bottom. And since we were that far to inspect the rear end.
Judging from the outside I didn’t hold much hope for the inside. But again to my surprise the rear end was full of oil and no water. Bolts looked good, gears looked good.
We cleaned all the surfaces, changed the oil and closed the rear end.

Next we took a look at the hydraulic system.
I’m glad we did.
More water than oil! We have flushed the system twice now and have good oil back in. Now we have all hydraulic operations working including high gear!
That’s where we’re at now. It looks like we will have a good running machine. That s really what we are after, mechanically sound and ready to go back into service. If you took the time to read all that, thank you! If you see something we missed or know of something else we should check please let me know. The pictures didn’t load so I’ll add them here. Thanks guys!

[JSinMO]

More pictures.

[JSinMO]

Still more pictures.

[DavidBarkey]

Well done , Wow what a find . You must have been kick by a horse in the back side at one point . As you probity already know seal harden . Now you are able to use it watch for leaks . What oil did you put in the engine ? It is suppose to have SAE 30 but I have found with mine 15w40 diesel oil works best in the summer .

Dave

[Eugen]

Great "will it run" story and wow, great find! So nice to see a machine like this gets to be freshened up by someone who knows what he's doing and gets another lease on life. Thank you for sharing with us and can't wait to see what's next!

[Timj]

Great project, good job it will be a handy machine to have around.
With reasonable care that Onan be around for a long time.

[MattA]

Glad to see the lack of high range was just a fluid problem and not sheared differential bolts

[JSinMO]

Thanks guys! We got pretty lucky with this one so far.

Dave,
Since the book called for SAE30 that’s what we put in it. I guess we’ll see how it does. So far we do have a leak on the ram for power steering, we’ll probably need a seal kit for that. The only other leak I noticed so far is on the cylinder for the loader, it will drip when the bucket is moved to full dump. We did start out by cleaning all the cylinder rams and running a little oil on them in the hopes the seals would soften up. We’ll have to keep an eye on it as we start using it

[propane1]

Nice machine. Sure would like to have one. But I doubt if there were even any sold here.

So I have a question. The tractor would not move in high range. But would in low range. How would the change of hydraulic system oil change that. And I realize there was water in it. Not enough pressure ? Could somebody enlighten me on that.
Thanks.

Noel

[Timj]

Nice machine. Sure would like to have one. But I doubt if there were even any sold here.

So I have a question. The tractor would not move in high range. But would in low range. How would the change of hydraulic system oil change that. And I realize there was water in it. Not enough pressure ? Could somebody enlighten me on that.
Thanks.

Noel

Probably Noel, the loader backhoes are heavy and not known to travel well in high. With water in the oil and possibly lighter oil, there was too much slip.