Firstly, may I say how impressed I am with this superb forum - friendly, informative and professional.
I seem to re-call reading that the head bolts should be loosely tightened down, then followed by further 90degrees + another 90 degrees. Is it OK just to simply tighten in the correct sequence to the relative torque settings. Putting blobs of paint on bolts seems a bit strange to me - or have I got the wrong end of the stick ?

- (#13670) gordon davies, 8 Oct 04 15:57

Gordon, the paint markings are to ensure that you don't miss a bolt or, overtighten one. This gives a visual guide, as you progress through the head tightening sequence, that every one of these stretch bolts are tightened to the correct torque. The bolts are tightened down, in the correct sequence to the maximum torque figure (not loosely tightened down)and then, in the same sequence, the first 90 degree turn and then the second. With 18 bolts, it is easy to miss one, and the paint marks tell you exactly the situation of each bolt. There are views on re-use or replacement of the bolts. My view is that the cost of new, correctly stretched bolts, is cheap compared to another strip down.

- (#13670) John Davis (Leics), 9 Oct 04 02:19

Gordon, in a nutshell, torque figures are meaningless. The headbolts are of the "stretch" or "torque to yield" variety. You are first settling the gasket and bolts down, then the 90+90 is stretching the bolts by a specific value. In fact you can work it out- 180deg is half a turn, so the stretch is half the distance between adjacent threads.

What is *slightly* unusual is that most other manufacturers recommend replacement of the bolts EVERY TIME whereas Toyota would have you wait until the bolt "doesn't feel right" on tightening- at which stage it's undergone plastic deformation and is but a short way from snapping, with the ensuing stripdown to recover the end piece.

I've had a bolt do just that on re-use, not in a Toyota, rather a Citroen. And I've got to say a. it feels really wierd when it starts to fail, and b. it's pretty heart-stopping...

- (#13670) David Miller, 9 Oct 04 02:49

Thanks to John and Dave for the advice. I hope to be re-fitting the head this week - and now have a much better idea of what is required.

- (#13670) gordon davies, 9 Oct 04 11:38