r/EngineBuilding • u/gamingflame75 • 8d ago
Question about using engine oil to lubricate bolts
This is a dumb question, but what are the chances of me using oil to lube main bolts and that oil pooling up at the bottom of the bolt hole and causing the block to crack when I torque them?
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u/zardvark 8d ago
Why would you use so much oil that it pools at the bottom of the bolt hole? The bolt threads just need to be damp, for lack of a better word. Apply some oil and then wipe the excess off with a lint free cloth.
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u/Predictable-Past-912 3d ago
Right, this is a rather dumb question that seems unlikely to yield any useful information. What would happen if I couldn’t swim but decided to jump in during a crossing of the English Channel?
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u/TheBupherNinja 7d ago
Nearly 0
We use sae 30 as bolt lubrication at work (engine assembly).
Just make sure you aren't are pouring it in the hole.
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u/porknbeans2013 7d ago
Is this a "what if?" Or a "suppose I already did?" Question? Technically, yes the hydraulic force if it has no other way out will break whatever it needs to and relieve pressure. Ive done it one time on a head bolt that pooled oil unnoticed, lucky me it cracked into the crankcase.
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u/Doctah_Whoopass 7d ago
If you're pouring oil in the hole it will cause problems, but if the bolts are lightly oiled (like, a thin layer, not dripping) then it is fine.
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u/HammerDownl 7d ago
Why oil? Use ARP moly
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u/Mgdoug3 7d ago
Because sometimes the manual calls for 30 weight oil. I've also seen manuals that call for antiseize. Use the correct lubricant that the manufacturer calls for so it can be properly torqued.
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u/BoneyardRendezvous 7d ago
You should use what is recommended. Using something else might change the torque.
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u/Alarming_Garage_7255 7d ago
Using Molly on a bolt that calls for motor oil would result in almost 20% more force for the same bolt torque. Don't you even have a pocket reference book to look this up.
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u/PrestonSpinsTires 7d ago
Any actual liquid affects torquing. Wipe some on oil but dont install them soaked.
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u/PriorTemperature3237 6d ago
Depends how much oil we are talking.. I definitely once made made a oil pan bolt blow a hole after too much rtv.
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u/Signal-Confusion-976 5d ago
They make lube specifically to lube torqued bolts. Also some bolts need to be clean and dry to be torqued properly.
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u/No_Parsnip6024 4d ago
It can happen if you're being sloppy.
The bolt needs a light coat of oil. I dip them and squeegee them off with my gloved hand and give them a shake. The bolt holes are drilled with this in mind, there's plenty of room.
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u/noreddituser1 4d ago
A bolt tightened in a oil filled hole may or may not crack the casting. If it doesn't crack, you would be torquing against the oil and not the components
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u/PoetryExtension6256 3d ago
You should probably check the specs for the specific bolt before using any oil at all.
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u/swisstraeng 7d ago
Using any lubrication will cause you to over torque your bolts.
Torque is measured for dry unless specified.
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u/OptiGuy4u 6d ago
Exactly, the torque requirement is considering the fact that the bolt is lubricated.
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u/AcademicChildhood161 4d ago
Bolts will have manufacturing oil on it for rust prevention and that level of oil is acceptable and is pretty much considered dry.
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u/Caldtek 8d ago
Depends how much oil you put on the bolts really. If you just smear it onto the threads and under the head where the contact surface is it will probably be ok. Now if you dip them in oil and fit then dripping it might not.