General Tech replace the head bolts

[sp53]

In General terms should people replace the head bolts after installing a new gasket. My concern is that I might be replacing a quality OEM product for a third world replacement because of a marketing/sales suggestion.

 

[tinman58]

From what I have learned from this forum. If the nut screws down the threads without binding you are good.

 

[Tim Tucker]

Buy a quality product from ARP if you do decide to replace.

 

[Hot Wings]

In general terms, no. That is unless the service manual says to do so because torque to yield bolts are used. If it is a torque to yield fastener then they are replaced, or in come rare cases measured to see if they have enough section area left to provide a full clamping load. If the torque sequence ends with turning the bolts a specified amount after an initial torquing with a torque wrench it's a good bet that the bolts are of the torque to yield type.

In a properly designed and torqued fastened joint the bolt will not fatigue and last indefinitely. If the bolt is not a torque to yield and there is corrosion or other damage on the bolt, or you don't know it's service history, then it may be prudent to use a new fastener.

If this is a repair rather than a simple rebuild I'd be more worried about figuring out why a new head gasket was needed in the first place.

 

[alanjohnturner]

There is no simple answer to this because most of the time re-using these bolts will work fine.

BUT

I have recently had to get a couple of guys out of deep trouble with head bolts broken off deep inside the block.
In one case this had been badly Helicoiled and this made the job much harder.

While doing this I checked the max torque for 1/2in grade 8 bolts. You can do the same.
Its quite close to the usual 110ftlbs used for head-bolts, at the UNC end.

These bolts are old now and cracks build up with time.

One way to check for a good quality bolt is a properly machined longitudinal groove in the thread, for oil relief