Oiling head bolts before installing?

[Gareth Randall]

In one of his videos, Eric recommends oiling the threads of cylinder head bolts before installing and torquing them. But I thought that would throw the torque reading out of whack?

Topic

[Bill]

Exactly the opposite. With no lubrication you have friction in the bolt threads and under the bolt head and does not provide accurate torque.

[619DioFan]

+ 1 on the above reply

[Konrad]

You should do what the service manual tells you to do. Some bolts are to be lubricated with engine oil, and some with a lubricant specified by the manufacturer. Although there is truth in that you can’t achieve an accurate torque setting without lubrication, it’s just as important to use the correct lubricant.

[Gareth Randall]

The service manuals for both of my cars (Jeeps) say nothing at all about lubricating the head bolts before installing them. One bolt needs special sealant because it goes through the water jacket, but that’s all.

I haven’t read all that many service manuals, but I’ve never seen any which state that head bolts should be lubed before installing. In Eric’s video, he offers it very much as a personal tip – “This is what I like to do” – rather than something that’s standard procedure whatever the vehicle.

Thanks for the info though, if oiling the threads actually helps, I might as well do it.

[Author]

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