scary comment

[froggy]

Hi, Iam hoping to replace the head gasket on my S2 Xantia this weekend.....well make a start just heard a comment by someone........" careful undoing the head bolts , because it is easy to snap them .....and then scrap it !! " is there any truth in this.....A very nervous Froggy

[citroenxm]

Is it an XUD S2?

Then not strickly.. however, I have heard of - in fact I have had - head bolts snap on an XUD but only ever on ONE engine on all the heads ive had off.. and thats a fair few!!

If all the unbolts un Torque easilly enough there will be no problem!

REMEMBER: theres a Metal Dowl in the cam belt side engine mount thats bolted to the engine - that needs to be removed, as it goes through the top of the mounting into the head..



Item 28 has a 10mm bolt in it that secures the Belt cover, then you remove that with a 13mm after the covers off, then item 29 NEEDS to come out to get the head off with the mount left in place, this needs something like a 16mm bolt!! Screw in a 16mm bolt or so, then it need levering out of place!! It doesnt screw out.. it will either pull out nice and easilly, OR it will be partly siezed!!! and a right PITA to get out!

[citronut]

on releasing the head bolts, you work in an ever increasing circle out to both ends, first stage only just crack each bolt off,

on tightening them back down you work in an ever decreasing circle one end of the head in to the center two bolts

also before re/assembly clean all the head bolt holes/threads in the block out thoroughly, otherwise it is possible to cause hydraulic damage to the block or and the bolts

[citroenxm]

Urrrm malc are you sure!!

You always do bolts Up From the middle OUTWARD to help push outward any issues.. ive never worked from the ends inwards on dooing up even haynes say tighten middle outwards...!!

[citronut]

sorry Sir Paul you are correct
yet another senior moment

it would all fall into place on the job honest .gov

so just completely revers my offering above

[CitroJim]

Here's a pictorial of the XUD tightening sequence



It holds good for many four-pots..

Terry, you will find the bolts feel 'funny' on initial undoing as they are stetch bolts and can feel a tad 'rubbery'

Malcolm is good is recommending little bites and I find additionally it's good to initially apply undoing torque with a long bar, feel the bolt 'give' a bit and then hold the torque steady and let the bolt sort of follow round.

What happens is the stretchy nature of the bolt causes it to twist in the middle when undoing torque is applied and you have to hold steady whilst the twist unwinds itself before continuing, It's over-twising the bolts that can shear them. Take it easy in small bits and let the bolts follow through in their own time and you'll be fine...

[Old-Guy]

I'm tempted to say "The Oracle has spoken!", the the ancient oracles tended to give ambiguous answers.

Sir Jim speaks from great experience and knowledge, his post is as clear, comprehensive and complete as could be wished for.

The advice to use a long bar (36"/900mm) is crucial. It's very difficult to tighten the (new) bolts correctly with anything shorter as you have to apply enormous torque in a very controlled manner - I speak from having had the Green Lady's head off twice in just over 12 months.

Before refitting the head:

Take the time to make yourself a couple of special 'tools' which will enable you to do the job properly (and save damaging a new head gasket!)
1. Make a long slot down the first 20-30mm of the thread of another old bolt and make absolutely sure all swarf and burrs are removed from this cut; clean up the sides of the slot with a thin Swiss file and (power) wire brush the threads.
Cut the head off two of the old bolts, grind/file the cut end smooth and with a chamfer and the put a deep screwdriver slot in it (make sure you have a screwdriver that fits, and is gripped by, the slot.
Tool 1 is used to thoroughly clean the threads in the block (do it once dry and a second time with the 'tool' lightly greased to pick up all bits of debris. Plug clean holes with twists of rag of paper until you're ready to fit the gasket and head.
Tool 2 are a pair of guide pins to hold the new head gasket in place and get the alignment of the head spot on. Fit them in diagonally opposite bolt holes at each end of the block (positions 8 + 10 or 7 + 9 in Jim's photo) - only screw down 3 or 4 turns. Fit gasket, fit head, fit bolts in the other 8 holes finger-tight only, then replace guide pins with new bolts.

The joint faces (head and block) must be perfectly clean, as must the new bolts, washers and bolt seating faces on top of the head. Lightly grease bolt threads (the threads in the holes have already been greased during cleaning), and both faces of the washers. This is important to stop the threads of faces binding when the bolts are tightened. Follow the specified method and sequence for tightening down the head bolts exactly.

It's not a difficult job with the right tools, just fairly time-consuming.

Best of luck

[lurchy666]

all im going to say is if you take the glow plugs out on it and its a hdi be carefull cause they snap very easily as I found out,

[citroenxm]

Here's a pictorial of the XUD tightening sequence

Oooooooooo a DW8 head there Jim.. one of yours? IE: not an xud head but simmilar

[Lighty]

Head bolts used to break a lot on the petrol ones, never had a major issue with a diesel .

[CitroJim]

Here's a pictorial of the XUD tightening sequence

Oooooooooo a DW8 head there Jim.. one of yours? IE: not an xud head but simmilar

Not one of mine Paul, never had anything DW8 powered. I 'borrowed' the picture years ago from somewhere and never returned it..

Actually I never realised it was a DW8. Thanks! You learn something new every day

[citronut]

Oooooooooo a DW8 head there Jim.. one of yours? IE: not an xud head but simmilar

how do you spot the difference Paul it looks like an XUD to me

[citroenxm]

Oooooooooo a DW8 head there Jim.. one of yours? IE: not an xud head but simmilar

how do you spot the difference Paul it looks like an XUD to me

Because I must be better then you then malc!!

no seriously.. its the heater plug locations.. preciesly where the xud should of had them in the first place.. ABOVE the injectors rather then below.. of course this means very long heater plugs but al least they are easyer to get at then xud plugs..