Engine head removal — reversed nuts sequence?

XK-Engine
1

Hello Everyone,
I am about to remove the head of a 3.8 XK engine (from a mk2) and I think the service manual is not very clear about the nuts sequence removal?
The removal explanation written in the mk2 manual says to refer to the figure 11 which is labelled for the head nuts tightening/torquing sequence. Which is basically from the central nuts towards the sides.
But when it comes to removing the head/nut, should it be reversed? (from the sides towards the centre?)

The XK120 manual is similar but a bit more specific as the explanation on the B.25 page (head removal) refers to the B.12 plate showing the “sequence for slackening or tightening”. So that would mean it’s always from the centre to the sides for both tightening and slackening on an XK engine?

Thanks in advance!

2

Just go from the centre out, theres probably no difference if you were to go out to in though to be honest.

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3

You are correct: it makes no difference, really, how one releases the nuts, so long as it’s in something of a circular order, inside out, or outside in.

2 Likes
4

Thanks guys! :slight_smile:
I will proceed in a moment!

(I am removing it because of a coolant leak; I first thought it was because of the rear core plug which looked wet but after I got the engine out of the car I noticed traces of coolant with a UV lamp on the block starting from the head gasket plane at the rear above the core plug, so … )

5

You can try retorquing first, but then one at a time, from the centre out please.

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6

And backing off before retorquing.

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7

That is a good suggestion but unfortunately I couldn’t do it because the engine is already out of the car (I was pretty convinced it was the rear core plug after seeing coolant on its base while it looked dry above it)

Anyway, the head is now removed from the block, nothing really obvious. The block and the water passage look great to my eyes, which is nice.

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8

The tightening sequence is all about crushing the gasket evenly.
For removal you don’t care about the gasket.
Distorting the head by not following a removal sequence seems unlikely to me, but perhaps back in 1949 Heynes and the other engineers thought it would. After all it was their first try at an aluminum head.
But if it makes you feel more confident, reverse the tightening sequence.

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