Replace head bolts or not????

[Rovernaut]

I contiplating fixing an oil leak on the head and am debating whether to replace the cylinder head bolts. I believe LR do not specify that it is a must, but read elsewhere that bolts can stretch and to replace them. At another $170 for a set I am in debate?

[Bush65]

Later head bolts have a tightening procedure that yields the bolts. These bolts should be replaced.

Previously bolts were tightened to a precribed torque that does not cause the bolts to yield. These bolts can be re-used.

Sorry I don't know when the tightening procedure changed. Perhaps when the number of headbolts was reduced to 10 per bank. Perhaps only with steel (not composite) head gaskets. Haven't had my heads off for years.

BTW there are good, technical reason for tightening to yield. I don't know if the bolts are different - they may well be.

Hope this helps. Someone else may be able to add more on this.

[Rovernaut]

Thanks bush65,
mine's a 1996 3.9 10 bolt head.

[mickrangie]

Thanks bush65,
mine's a 1996 3.9 10 bolt head.

if you pull the bolts out then u should be able to tell if they a strech bolts or not there should be part of the bolt that looks a bit thinner then the rest... I have 93 3.9 and my wernt strech bolts I fink that the strech bolts were used on the 4.0 / 4.6 in later models (dont quote me on this)

HTH

[Rovernaut]

I found the answer on the LR CD.
Engines with a suffix of "B" are torque to yeild bolts. ( these need replacing) Mine is suffix C which is after "B" so I will have to replace them.
Engines without suffix "B" have re usable bolts that torque in poundage stages.
Bolts to yeild however are initially torque to poundage then torque to yeild via 2 stages of 90 degrees, giving a total of 180 degrees.

Early engines use a shim metal gasket, later ones use the composite gasket.