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Subject: Locked up motor after rebuild

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Scott    Posted 05-19-2020 at 11:59:57 [URL] [DELETE]        [Reply] [Email]  
  • Locked up motor after rebuild
  • I have just finished a rebuild on my 1952 8n engine. Sleeves, rings, pistons... the whole works including a new crankshaft and bearings. I assembled using assembly lube and torqued to spec after checking bearing clearance with a plastigauge. Everything is in spec for torque and clearance. The engine was hard to turn over by hand/ratchet but I could get it to turn over. The last thing I did while it was on the stand was to give it a try and it was tight, but moving. I installed the flywheel and clutch and mated it to the tractor. Now the starter wont even turn it over. Fully charged battery, etc. My question is, could I have installed the flywheel incorrectly causing it to bind and prevent the starter from being able to turn the engine over? The spark plugs are removed during all of this. I tried rocking the tractor back and forth and having my wife dump the clutch just to see if I can get the engine to move but it wont. Any ideas on what could be wrong?

    Scott    Posted 05-21-2020 at 14:34:07 [URL] [DELETE]        [Reply] [Email]  
  • Re: Locked up motor after rebuild
  • I remember the last thing I did prior to removing the engine from the stand was to turn it over, and it turned over tight, but okayish. After that, I installed the flywheel and clutch and bolted the engine to the rest of the tractor. This is leading me to believe that the flywheel, or more specifically, my installation of, may be the culprit. I plan on pulling the engine this weekend if the weather allows and removing the flywheel and attempting to turn it by hand. Once its pulled away from the bell housing and the transmission input shaft is not contacting, I will bump it with the starter and see if it could be something in the tranny, although I feel that is not likely. Any thoughts?

    JMOR    Posted 05-22-2020 at 00:38:05 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Locked up motor after rebuild
  • Get it done.

    Mike W    Posted 05-20-2020 at 18:13:56 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Locked up motor after rebuild
  • Sometimes the rope seals can clamp things pretty tight. If it will turn some with a wrench on the crank bolt you could consider pulling it. Fourth gear, clutch down, go slowly, ease up the clutch. Goes without saying that anything unusual, noise or vibration and so forth, the clutch goes back down NOW.
    If it is the ropes a short pull will loosen it up.

    Bruce(OR)    Posted 05-20-2020 at 15:20:12 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Locked up motor after rebuild
  • Pull the plugs, loose the compression. crank it over.

    steveVa    Posted 05-20-2020 at 10:35:23 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Locked up motor after rebuild
  • I would oil everything real good with 5w20 rings and all, make sure you kept main caps in order with orientation etc. Try turning with a breaker bar like toh said. If it won't turn with a wrench, rock it in high gear and see if it budges.

    Dave H    Posted 05-20-2020 at 06:26:16 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Locked up motor after rebuild
  • Hate to be a nay sayer, but I would never try to start one that is that tight.

    I will always remember the time I got an undersized insert in a standard box.

    HCooke    Posted 05-19-2020 at 17:14:30 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Locked up motor after rebuild
  • " Now the starter wont even turn it over. Fully charged battery, etc."

    6 or 12 volt? If six volt, try jumping 12 volts to the starter.

    Scott    Posted 05-20-2020 at 09:00:25 [URL] [DELETE]        [Reply] [Email]  
  • Re: Locked up motor after rebuild
  • It is a 12v

    HCooke    Posted 05-21-2020 at 12:38:07 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Locked up motor after rebuild
  • Then I would try pulling it.

    bkrsdoz    Posted 05-19-2020 at 16:38:49 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Locked up motor after rebuild
  • I assume you checked all mains and rod bearings with plastigage for clearance.
    You also checked piston ring end gaps before assembly of the pistons/rods.
    It shouldn't have been that tight on the stand.

    Scott    Posted 05-20-2020 at 09:03:44 [URL] [DELETE]        [Reply] [Email]  
  • Re: Locked up motor after rebuild
  • The only thing I didn't check was ring end gaps, but it wasn't difficult to get the pistons in the cylinders or to push them into place. Other clearances were good. Its a new crankshaft bought as a kit from Yesterdays tractor. It came with bearings and when torqued, the clearances were within spec, although I cant recall off the top of my head what they were.

    TheOldHokie    Posted 05-19-2020 at 16:20:40 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Locked up motor after rebuild
  • Can you turn it over with a wrench on the crankshaft pulley bolt?

    TOH

    Scott    Posted 05-20-2020 at 09:06:00 [URL] [DELETE]        [Reply] [Email]  
  • Re: Locked up motor after rebuild
  • I haven't tried yet. I got disgusted when it wouldn't turn over so I walked away from it. I'll try when I get home to do some more troubleshooting.

    JMOR    Posted 05-19-2020 at 12:44:22 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Locked up motor after rebuild
  • Correct length bolts in clutch/PP/flywheel assy?

    Scott    Posted 05-19-2020 at 15:17:20 [URL] [DELETE]        [Reply] [Email]  
  • Re: Locked up motor after rebuild
  • Yes the bolts are the correct length. The same ones that came out of the flywheel before the rebuild. This was a running tractor prior to the rebuild, just didn't have compression or oil pressure.

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