I am ready to refit my cylinder head, on my 1.2 80sx, and a red warning sticker on the gasket set says always use new cylinder head bolts. This is quite common nowadays as they are often meant to stretch when fitting However the Haynes manual says you can refit the original ones. It also says that you should angle tighten the bolts twice, by 90deg. This last turn being the fourth stage in the tightening sequence. In my experience its odd to angle tighten more than once. Is this correct ? Does anyone know what the official Fiat workshop manual says ?
Martin

thats right, new bolts and angle twice, but how does that make it fourth stage?

Sorry, I dident make it clear in my first post. According to the Haynes manual the full sequence is A 20nm. B 30nm. C 90deg. D 90deg. Frankly I think that is to much for the 3/8th drive adapter on the end of the torx (or whatever its called) socket. I have spoken to a friend who is a qualified engineer and he does not think this is right as just one angle tighten is usually the final stage.
Martin

well all the 8v fire engines you angle tightern twice, A 20nm. is hardly tight at all

i've always done it twice, even with used bolts and stretch bolts (your car doesnt have stretch bolts as far as i know). i usually leave the second 90deg turn until after a few miles of driving.

jug said:

i usually leave the second 90deg turn until after a few miles of driving.

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i would advise against that, its not an iron head

good point

Crank said:

Sorry, I dident make it clear in my first post. According to the Haynes manual the full sequence is A 20nm. B 30nm. C 90deg. D 90deg. Frankly I think that is to much for the 3/8th drive adapter on the end of the torx (or whatever its called) socket. I have spoken to a friend who is a qualified engineer and he does not think this is right as just one angle tighten is usually the final stage.
Martin

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Qualified in what?

The total of 180 degree split in 2 90 degree turns is common practise on many engines. On your engines the second stage is only 30Nm. Turning it once 90 degree would soon lead to head gasket failure.

Haynes is not wrong with stating that you can re-use the bolts. Still, I wouldn't do it as it sometimes leads to problems. I rather spend the extra £10 or so.

Also it is necessary to oil the thread and let it drip off for 30 minutes to guarantee that the bolts are torqued down evenly. After the second stage you should go through the sequence at least once more and then leave it for some time and go through the sequence again before the 2 90 degree stages.

Just do it like the manual says, with all sequences done directly after each other working sequencially from the centre out. Manufactures dont wait 20 mins between tightenings and they last for tens of K's of miles. All ali heads use stretch bolts to compensate for the extra expansion, and extra strain on bolts. By repeating the stretching cycle re-used bolts could easily go beyond their elastic limit causing "necking" with the resultant ineffectual clamping of head. Use new bolts, its just not worth the possibility of doing it again.
Tony, also qualified (over 40 years ago, but the science is just the same).