Crankshaft bearings

Gordy1

New User
Hi, I have a problem fitting a crankshaft bearing in my I.H 784 tractor, when I fit the new bearing & tighten it to the specified torque the engine will not turn, I put the old one back on & it does the same, the crankshaft can be turned by hand when the bearing is taken off, can't see where the problem lies, like I said I tighten to the specified torque. Can anyone throw any light onto this??, any help will be appreciated, regards gordy1
 
Best get the crank checked for straightness, and block main saddles for straightness too while your there. Assuming the bearing and crank journal match size wise..
 

Try giving some history about your project. Most automotive machine shops will check main bearing alignments to a very close tolerance and often align bore them.
 
A lot more info is needed here. Are you doing an inframe or do you have the engine out and
disassembled ? Is it only doing it on one particular bearing? Was that bearing locked when
you disassembled it? Are you doing a complete rebuild or a patch job? What is the
condition of the crankshaft? Do you have a set of mics? Do you know what Plastiguage is?
 
Could be you got an undersize bearing that was mismarked. I got a set of mains that had no oil hole in the pair with thrust faces. Sometimes a mistake gets through.
a178811.jpg
 
If the cranks not bent and the blocks ok for the mains alignment . If it does it with the old bearing as well, just a long shot are you putting the bearing caps on the right way round and back in the right order of removal. They are usually numbered for location but if not a number system should be added with a center punch or number stamp so they go back the same .

I have never seen it in person as a problem but have heard several guys on other forums get the cap on backwards or in the wrong place to where it was line bored in the factory and the crank wont turn. those locating lugs on the bearing shells should "usually" both be on the same side of the journal( not opposite each other across the journal) when you put it together with the cap on the mains and rods. I have heard if a guy puts a rod in round the wrong way on some motors it will lock the crank to
Regards Robert
 
The first thing I would do is to measure the journal and then the beating shells to see if the bearings were correct.
Eliminate one possible problem at a time.

2vSwin48xevZ4.jpg
 
(quoted from post at 13:20:20 11/24/17) BEARING SHELL!! Fat fingered over the R and hit the T.

Don't worry about it Dick. Spell check is getting all of us. I wish that we could go back to the good ole days of just having a red line under a miss-spelled word instead of spell check changing your word for you. Who would have thought that the good ole days would ever be post computer???? What is this world coming to???
 
That method will work.

I've sorted out basket case engines that were torn down without marking any rods or mains. I measured just the bores without bearings though.

You can also match up rust/oil stains under the cap and block surface.
 
(reply to post at 04:30:01 11/29/17)
i all, thanks for all your replys , the crankshaft now sorted not quite sure what the problem was but it turns over now but the problem doesn't end there!!!, turns over slowly but seems the battery runs down after two or three turns!!!, replaced the starter motor same thing happens, replaced the battery with a new one still happens!!!,..... can anyone advise what maybe going on with the thing!! Before this problem it turned over fairly slow but would start though.
 
hi all, thanks for all your replys , the crankshaft now sorted not quite sure what the problem was but it turns over now but the problem doesn't end there!!!, turns over slowly but seems the battery runs down after two or three turns!!!, replaced the starter motor same thing happens, replaced the battery with a new one still happens!!!,..... can anyone advise what maybe going on with the thing!! Before this problem it turned over fairly slow but would start though.[/quote]

Sounds like your problem has really not mysteriously disappeared. So when you say it turns over, does that mean that you can turn it by hand? Really can't help you, you won't give anything to go on, you have ignored all efforts to help so far.
 

Gordy1, I responded to the other thread, here it is:


Sounds like your problem has really not mysteriously disappeared. So when you say it turns over, does that mean that you can turn it by hand? Really can't help you, you won't give anything to go on, you have ignored all efforts to help so far.
 
(reply to post at 23:03:51 11/30/17)
hi, going back to the beginning the engine started knocking after a few minutes as it was warming up,( had the same trouble with a ford) after a couple of times it wouldn't turn over like the engine had ceased, dropped the sump off to try to see what might have gone wrong from underneath & sure enough the back crankshaft bearing was dislodged and stopping the crank from turning (just like the ford)when the bearing was removed the crankshaft turned ok by hand, as the bearing was badly scored had to take another one off for the identifying number for a replacement, that one was replaced & a new one put in to replace the scored one tightened it up to the right torque but the crankshaft would not turn, decided to put the old one back just to see if the new one might have been the wrong size but it still wouldn't turn took them both off again then it turned over by hand ok, replaced the old scored one with the new one & eventually got it turning by loosening them off & tightening it several times, put back together then tried turning it on the key, just turned two or three times then seemed the battery had run down, it was ok before when it was running so thought it may be the starter motor playing up, changed that with a new one but made no difference so replaced the battery with a new bigger one (cca 800) & that made no difference even though it was fully charged, seemed to run down after a few turns, have checked leads & earths all ok & nothing getting hot, haven't had time to look at it today...... so there you go....
Or should I say where do I go from here other than giving it a bit of a tow with the stop button out in case it fires up,just to see if everything is seating ok & nothing else is stopping it, any advice fellas??
 

please elaborate on this part: "the back crankshaft bearing was dislodged and stopping the crank from turning"
 
(reply to post at 01:05:03 12/02/17)
i, Sorry for any delay in getting back to the subject it must be a time thing as I am in the UK, as I said when dropping off the sump found the rear c/shaft bearing dislodged & badly scored & was unable to read the serial number for the replacement part so had to remove another one to get it, gave the number on it to a tractor engineering company who said it was a standard bearing that was required so bought a set of four but only replace the affected one, that's when the problem started, tightened up to specified torque & the crank wouldn't turn even tried replacing the old one in case the new one wasn't the right size but same thing happened, took that back off then it turned put the other one back on that I got the number off then the crank wouldn't turn again, eventually got it turning after putting the new one back on by tightening it & loosening it several times & away it went, put it all back together & tried it on the key & just a slow turn over a few times & nothing ,the rest is history.hope this makes sense to you.
 
Hi, Sorry for any delay in getting back to the subject it must be a time thing as I am in the UK, as I said when dropping off the sump found the rear c/shaft bearing dislodged & badly scored & was unable to read the serial number for the replacement part so had to remove another one to get it, gave the number on it to a tractor engineering company who said it was a standard bearing that was required so bought a set of four but only replace the affected one, that's when the problem started, tightened up to specified torque & the crank wouldn't turn even tried replacing the old one in case the new one wasn't the right size but same thing happened, took that back off then it turned put the other one back on that I got the number off then the crank wouldn't turn again, eventually got it turning after putting the new one back on by tightening it & loosening it several times & away it went, put it all back together & tried it on the key & just a slow turn over a few times & nothing ,the rest is history.hope this makes sense to you.[/quote]

Please elaborate on "dislodged". It sounds like you could have a bent crank but need more info. Also there are three "standard" bearings. Did you check the bearing clearance with plasti-gauge?
 
If I was to guess without any measurements to go on I would guess that the crankshaft was ground undersize on all but one journal. That would mean the bearing that is tight has to small of an ID. It can happen.

Back in the 1960's I had a rod start knocking on my race car. That was a Friday Night and I wanted to race the next Sunday night. I took the car to a local garage that could grind a crankshaft in the engine. He put the car on the hoist and packed the block with grease rags and ground one journal and fit an under size bearing on just the one journal. That allowed me to go to the track and loose my entry money. :)^D A week or two later I put in a new crankshaft along with more stuff that was a waste of money. Wasn't smart enough to know it at the time.

Might not be your problem but your not going to know unless you measure your crankshaft.

If all else fails cut a leather bearing. A snug fitting leather bearing shell will last longer than most would think. This should have a hint of sarcasm.
 
(reply to post at 23:44:20 12/02/17)
Hi, it became dislodged due to ware & tear I presume, it was quite scored, the crank itself doesn't appear to have any marks on it but maybe worn I suppose, I haven't tried plastigauge or a micrometer so I will do that, didn't know there were 3 different standard sizes of bearings, I just gave the number on the other bearing to the agricultual engineer & he sold me a standard set of four, I only replaced the worn out pair of shells though, It took a bit of time loosening & tightening before the crank could be turned by hand from underneath, it was still a bit stiff but put it down to the new bearing, tried towing it around the yard yesterday but couldn't get enough grip on the wheels to engage the engine, probably good thing though, will strip it down & measure up properly this time short cuts aren't a good way forward!!! are they. Thing is though, it was an identical job on the ford & it was straight forward & running ok now, seems to be more involved with the "784".
 
Hi, it became dislodged due to ware & tear I presume, it was quite scored, the crank itself doesn't appear to have any marks on it but maybe worn I suppose, I haven't tried plastigauge or a micrometer so I will do that, didn't know there were 3 different standard sizes of bearings, I just gave the number on the other bearing to the agricultual engineer & he sold me a standard set of four, I only replaced the worn out pair of shells though, It took a bit of time loosening & tightening before the crank could be turned by hand from underneath, it was still a bit stiff but put it down to the new bearing, tried towing it around the yard yesterday but couldn't get enough grip on the wheels to engage the engine, probably good thing though, will strip it down & measure up properly this time short cuts aren't a good way forward!!! are they. Thing is though, it was an identical job on the ford & it was straight forward & running ok now, seems to be more involved with the "784".[/quote]

I still don't know what you mean by "dislodged". To me it means out of place as in lying in the bottom of the oil pan but I don't know how that is possible. I think that what you may mean is that the bearing turned within the confines of the bearing cap, which is called spinning the bearing or the motor spun the bearing. Spinning a bearing can cause additional damage such as damage to the crank beyond just scoring, and it can cause the block.
 
(reply to post at 13:45:55 12/03/17)
That's about right, "spinning" as you say, suppose "dislodged" was the wrong word,
Anyway now waiting for the right equipment to be delivered then see how we get on. Thanks for all your replies & will keep you informed with the outcome.
 

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