Head Bolt Sealant?
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First of all we need to know what you are working on. A Chevy? A Briggs & Stratton lawn mower? A Ferrari?
If you are assembling a stock engine, with stock head bolts, it is time you got a factory service manual. Not only will it tell you what lubricant to use, it will tell you the torque value, and the sequence you tighten the bolts in. You might also have an engine that requires the intake manifold, or other parts to be to be installed before completing the head bolt tightening process. The manual will also tell you if you can reuse the head bolts. On some engines, you do not reuse head bolts.
If you are using aftermarket bolts, follow the directions that came with them.
But before you start, you need to get a bottoming tap, and chase the threads in the block, to clean them out. If you are reusing the stock bolts, clean the threads on them, also.
If you are assembling a stock engine, with stock head bolts, it is time you got a factory service manual. Not only will it tell you what lubricant to use, it will tell you the torque value, and the sequence you tighten the bolts in. You might also have an engine that requires the intake manifold, or other parts to be to be installed before completing the head bolt tightening process. The manual will also tell you if you can reuse the head bolts. On some engines, you do not reuse head bolts.
If you are using aftermarket bolts, follow the directions that came with them.
But before you start, you need to get a bottoming tap, and chase the threads in the block, to clean them out. If you are reusing the stock bolts, clean the threads on them, also.
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For stock type Chevrolet head bolts I use Teflon plumber’s paste type pipe sealant. Easy to find at most any hardware store and much cheaper than the repackaged stuff at the parts store. In torque tests it is very close to motor oil which the factories use on the threads and under the fastener's head for their torque tables, so you don't need to make adjustments to the torque values for the lubrication medium.
Many aftermarket bolts and studs (such as ARP) specify a thread sealant/lubricant that has significantly different slipperiness compared to motor oil. In that case use the product the bolt manufacturer specifies.
You have to keep in mind that what you're doing is developing a clamping force by stretching the fastener. Torque is a secondary feature of that action which can be related to bolt stretch if a set of condiitons are met. The conditions are clean, and standard pitch and depth threads, compatible materials that do not gall with the application of force, and a lubricant that gives repeatable and consistant lubrication between sliding sections of the materials used and forces applied. It is clear from all the contingencies that the process of reading torque to arrive at bolt stretch is frought with the possibilities of error to the torque reading against that amount of stretch. Plus at the end of all this where bolts run into coolant passages, they must not leak. Nothin' to it, right?
Bogie
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Consider using new OEM type bolts for a mild build, some actaully come with the thread sealant on them out of the box, this is a dried paint on teflon sealant same as the brush on canned product mentioned.
A rule of thumb I use,,, once the bolt has been torxed 3 times its time for new, if you are unsure how many times then spend the cash and dont worry be happy.
A rule of thumb I use,,, once the bolt has been torxed 3 times its time for new, if you are unsure how many times then spend the cash and dont worry be happy.
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Permatex 3.
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