When do you re torque the head bolts?
Tighten each head bolt in the same sequence as before while the engine is still warm. If the engine has an aluminum cylinder head or block; however, do not re torque the head bolts; until the engine has cooled back down to room temperature.
What happens when torque is removed from an engine bolt?
In this phase, the bolt is stretched as torque is applied to it, but should the torque be removed the bolt will return to its original length. It is important to remember that in the elastic phase, the bolt will not provide sufficient clamping force to hold the cylinder head down reliably.
What happens if you over torque a cylinder head?
When you overtorque above 15% of recommended which in this case would be about 95 ft/lbs you basically turn the fastener into a rubber band. Some of the fasteners will stretch and you will have uneven torque. Add heat and pressure and head gasket blows and the head can even warp.
Why do head bolts need to be inspected?
Problems with head bolts are the number one cause of installation-related gasket failures. Consequently, No gasket is going to seal well if you use the wrong procedure to tighten the head bolts. So, Make sure the torque specifications you are using are the latest, up-to-date numbers.
What is the torque for bolts?
Different bolt sizes and grades have different torque specifications. For example, 6 mm bolts with a 10.9 grade have a maximum torque value of 10 foot-pounds, while the same-size bolts with a 12.9 grade have a maximum torque value of 12 foot-pounds. Consult your shop manual for the most precise listings.
What are torque specifications?
Torque specifications are for dry threads only. The fastener threads should be free of oil, dirt, grit, corrosion, etc. The hardware should turn freely without binding when tightened by hand. It is important NOT to lubricate hardware threads or seats. The friction at which torque is measured against should come from the hardware seats.
What is a torque screw?
Screw Conveyor Torque. Torque is defined as the twisting force exerted by the drive unit on the conveyor screw. Torque is transmitted through the drive shaft of the drive unit to the screw and converted to force to convey the bulk material.