head bolts that are not tight enough, will definitely allow pressure into the coolant and reduce compression alot. try it again and torque those bastards down right..
Also question is, what can occur if bolts are not torqued properly?
Uneven loading created by unevenly tightened head bolts can distort the head. Over a period of time, this may cause the head to take a permanent set. So any head that has not been properly torqued should be checked for flatness prior to installing a new head gasket.
Secondly, what happens if you over tighten head bolts? 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.
Regarding this, do you have to re torque head bolts?
Certain types may require you to re-torque the head bolts. And if it's needed, you should do it. Re-torque the bolts as required while your engine is warm. But if you're using aluminum cylinder heads, you should wait until your engine is complete cooled until re-torquing.
How much torque is required for tightening the cylinder head?
If an engine produces 1,500 pounds of pressure and the cylinder head has 8 bolts, then each bolt must be tightened to 187 foot-pounds of torque to secure the cylinder head to the block.
Related Question Answers
Can I reuse torqued bolts?
“Reuse: ASTM A490 bolts and galvanized ASTM A325 bolts shall not be reused. When approved by the Engineer of Record, plain finish ASTM A325 bolts are permitted to be reused. Touching up or re-tightening bolts that may have been loosened by the installation of adjacent bolts shall not be considered to be a reuse.”Can I reuse cylinder head bolts?
When You Should Definitely Not Reuse Head Bolts Bolts with any signs of damage, no matter how slight, should never be reused. Not only will the bolts eventually fail, but when they do, there is the potential for them to cause damage to your cylinder head.How many times can you reuse a bolt?
However, because the tightening procedure does permanently stretch the bolt, there is some risk of breakage if the bolt is reused. And since there is no way to tell how many times a bolt has been reused, it doesn't make any sense to reused TTY bolts – the risk far outweighs the replacement cost of used bolts.Why do bolts need to be torqued?
Torque is used to create tension. Bolts are used to affix two components so that they can resist tensile (pulling apart) and shearing (sliding apart) forces. After the nut has been turned onto the bolt, additional torque causes the nut to turn and stretch the bolt.Should I replace head bolts?
yes, you want to replace them. When head bolts are torqued they are supposed to stretch. They are only made to stretch once. if you reuse them you have a good possibility of one of them snapping which will cause big problems.What is the torque for head bolts?
Tighten each bolt to 12-15 foot pounds of torque. 3, Tighten each bolt to 22-25 foot pounds of torque. 4, Tighten each bolt to 38-42 foot pounds of torque.Can you reuse Grade 8 bolts?
Snugged Bolt Reuse F3125 Grade A325 bolts that are snugged can usually be reused. Snugged F3125 Grade A490 bolts and galvanized Grade A325 bolts can only be considered for reuse if snugged by hand or very lightly snugged with an impact wrench.What is the final step when torquing down head bolts?
The final step is to twist each bolt a specified number of degrees to stretch the bolts to their design limit. * If a bolt breaks when you are tightening it, you may have over-stretched it.Are head bolts tightened past their yield point?
To achieve this the TTY head bolts are tightened past their yield point into the plastic phase. In other words if the bolt is tightened past its yield point it will not return to its original dimension or state when the loading is released. This is due to plastic deformation!Can you use a head gasket twice?
Registered. FelPro has said that if the engine has not started and the gasket is returned to the same cylinder bank and head you can reuse the gasket.Why are studs better than bolts?
Studs provide the ability to obtain much more accurate torque values because the studs don't twist during tightening as do bolts. Because the studs remain stationary during nut tightening, the studs stretch in one axis alone, providing much more even and accurate clamping forces.What are torque to yield head bolts?
Torque-To-Yield Bolts Once they reach this zone, they maintain a more precise and consistent level of clamping force across the entire head-to-block mating surface. The bolts are stretched into their elastic range, and in many cases, the stretching approaches the bolts' elastic limit, permanently stretching it.Do bolts stretch?
All bolts stretch when they are tightened, but usually they stay within their 'elastic limit'. So, when they are loosened, they return elastically to their original length. The normal tightening method is by torque wrench.What happens if you over tighten oil drain plug?
If you over-tighten the drain plug, you can strip the threads. And while it's harder to do, you can damage the rubber gasket atop the oil filter if you really overtighten it. In the shop, we tighten the oil plug about as much as we tighten a spark plug.Should cylinder head bolts be oiled?
As a rule, the threads and underside of the head on most standard automotive head bolts should be lubricated with motor oil before the bolts are installed. The torque values specified by the engine manufacturer are typically based on oiled threads and fasteners – not dry fasteners.Are Honda head bolts torque to yield?
Yes - those are also called 'Torque To Yield,' or TTY. Meaning that they have been engineered to stretch once they exceed the intended torsion value after installation, rather than breaking or holding fast for other potential engine damage during an over-pressure situation.Can you reuse torque to yield head bolts?
Torque-to-yield (TTY) head bolts are designed to stretch when used. Once stretched, they are not as strong as before. Consequently, they cannot provide the same amount of clamping force and may break or shear off if reused.Can you reuse head bolts?
Reusing head bolts on your engine is not usually recommended by dealerships and car manufacturers. However, when you change your head gasket, or do other mechanical work to the head assembly, you can reuse your head bolts if they are in good condition and you follow a few tips. 
