Author Topic: Big end split pins  (Read 263 times)

Jordan

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Big end split pins
« on: January 25, 2019, 01:43:22 PM »
I discovered there are castellated nuts fastening the cap to the conrod of my CS1.
There are no split pins fitted.
It appears to have run for an extended time this way, going by the sludgy black stuff in the sump.
I'd like to fit some split pins if I can.
One of the nuts has a slot that lines up with the hole in the conrod bolt.
But the other bolt does not have a hole visible - likely just not lined up with the nut's slot.
Trouble is, the nut is very tight indeed. I could only get it to budge slightly, in the direction that would make it tighter.
I'm not to keen on loosening the nut to get it lined up with the hole.
Am I safe to continue running the engine as is, without the split pins?
Any suggestions for lining up the hole with the nuts' slots?

BruceM

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Re: Big end split pins
« Reply #1 on: January 25, 2019, 05:07:20 PM »
Bad idea to not use the cotter pins, I think.  Then shim shim stock can be used if the hole doesn't line up at appropriate torque. 

I do agree with your previous owner that the castelated nuts/pins are a PITA. But a loosening nut would be an potential crankshaft wrecker, for starters.

ajaffa1

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Re: Big end split pins
« Reply #2 on: January 25, 2019, 09:25:00 PM »
Hi Jordan, it sound like someone has been tinkering with this engine before you got it. There are small  shims between the cap and conrod. These allow the bearing clearances to be adjusted. My best guess is that the bearings have worn and someone has removed the shims to compensate. If the nut is as tight as you say it will be OK to back it off until the hole lines up. If you have a magnet, go fishing with it in the sump, every chance the missing split pin is in there.

Bob

Jordan

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Re: Big end split pins
« Reply #3 on: January 26, 2019, 12:17:22 AM »
Nothing loose at the bottom of sump, which was cleaned out.
Would self-locking big end nuts be a safe alternative?

ajaffa1

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Re: Big end split pins
« Reply #4 on: January 26, 2019, 12:32:20 AM »
Hi Jordan, much better to use the castellated nuts. A trick I have used a couple of times in the past is to take off the castellated nut and run a file across the flat face a couple of times. Re-torque the nut and see if the holes line up. repeat until they do. You should only be looking at filing off a couple of thou.

Bob

38ac

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Re: Big end split pins
« Reply #5 on: January 26, 2019, 01:36:25 AM »
The  correct way to install those type nuts is to tighten them up until they are snug but not tight then advance the nut to the next slot that lines up.  Yes it takes some feel for what's going on, snug would be defined as  25/30 foot pounds or about all the average person can pull with a standard  length wrench  with one hand. The one without the pin I would loosen and tighten the way I just described.
Collector and horder of about anything diesel

Jordan

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Re: Big end split pins
« Reply #6 on: January 26, 2019, 03:32:17 AM »
A couple of good suggestions there, thanks fellas.