Head Bolt Lube

[Kenobi77]

Due to my own impatience and forgetfulness I took ended up not putting oil on my head bolts before torquing them to spec. Would rather not elaborate. The bolts went in fine even though they were completely dry but I’m second-guessing whether I should just take them out and redo the gasket job before I go any further.

In other words, is it completely 100% necessary to oil the bolts? My factory shop manual mentions nothing about oiling them while also specifically mentioning oiling con rod bolts. I’m leaning towards “no” but want to make sure. Thoughts/experiences?

 

[SenorNoob]

I seem to remember the 4.0 head bolts being in a plastic package with oil on them already... It's not much. I'm gonna say if you couldn't feel them binding before they touched the head you're good.

 

[gaz]

@Kenobi77
Head bolts, NO lube; I was taught to hit them with a the wire wheel on the bench grinder after cleaning. It takes off (rounds) the machining crown (point) on the threads so that they can slide in nice and smooth.

 

[Curious Hound]

My official answer is "follow the directions". If the procedure doesn't tell you to lube them, then don't. Also keep in mind that torque specs are different between lubed and dry threaded fasteners. So, if you install them dry, use dry torque specs. If you lube the threads, use lubed torque specs which will be lower than dry torque.

 

[85_Ranger4x4]

My official answer is "follow the directions". If the procedure doesn't tell you to lube them, then don't. Also keep in mind that torque specs are different between lubed and dry threaded fasteners. So, if you install them dry, use dry torque specs. If you lube the threads, use lubed torque specs which will be lower than dry torque.

+1

There is no hard and fast rule and it varies greatly on how the people that designed the engine specced it.

 

[Shran]

When I reinstalled the heads on a 4.0 recently I remember seeing that oiling the bolts was required. What happens if you don't do it - I have no idea, they are torque-to-yield bolts so my guess is that you will arrive at your torque spec much sooner.

 

[85_Ranger4x4]

When I reinstalled the heads on a 4.0 recently I remember seeing that oiling the bolts was required. What happens if you don't do it - I have no idea, they are torque-to-yield bolts so my guess is that you will arrive at your torque spec much sooner.

Probably for consistancy.

If some bolt holes have oil and some don't they won't all be torqued the same. If you oil them all then regardless of bolt hole conditions they will all have oil and torque more evenly.